Evaluation of Wastewater Filtration
Utah State University DigitalCommons@USU
Reports Utah Water Research Laboratory
January 1981
Evaluation of Wastewater Filtration
Bryant L. Benth
E. Joe Middlebrooks
Dennis B. George
James H. Reynolds
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Recommended Citation Benth, Bryant L.; Middlebrooks, E. Joe; George, Dennis B.; and Reynolds, James H., "Evaluation of Wastewater Filtration" (1981). Reports. Paper 606. https://digitalcommons.usu.edu/water_rep/606
This Report is brought to you for free and open access by the Utah Water Research Laboratory at DigitalCommons@USU. It has been accepted for inclusion in Reports by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. EVALUATION OF WASTEWATER FILTRATION
Bryant L. Bench, E. Joe Middlebrooks, Dennis B. George, and James H. Reynolds
Utah Water Research Laboratory College of Engineering Utah State University Logan, Utah 84322 WATER QUAUTY SERmS January 1981 UWRL/Q-81/01 EVALUATION OF WASTEWATER FILTRATION
by Bryant L. Bench, E. Joe Middlebrooks, Dennis B. George, and James H. Reynolds
WATER QUALITY SERIES UWRL/Q-81/0l
Utah Water Research Laboratory College of Engineering Utah State University Logan, Uta h
January 1981 ABSTRACT
Tertiary filtration of secondary wastewater is The four filter beds were equally effective in frequently used to improve wastewater treatment plant removing suspended solids and biochemical oxygen effluent quality. Four experimental filter columns demand. were operated at the Preston, Idaho, Wastewater Treatment Plant to evaluate the effectiveness of The coal layered filters operated for 22 hours granular media, gravity filtration. The Preston maximum. The longest filter run time for the sand plant is a trickling filter secondary treatment plant filters was 9 hours. and services a population of approximately 3600 people. Filtration of the Preston treatment facility Four filter medium configurations were studied. effluent did not consistently produce an effluent Multi-media, dual-media, and single-media beds were that would satisfy the 10 mg/t BOD5 effluent constructed with the following media configurations: discharge requirement. (1) coal-sand-garnet; (2) coal-sand; (3) sand-garnet; and (4) all sand. A survey conducted to review approval criteria and design standards for wastewater filters The filters were operated at two hydraulic employed by state regulatory agencies indicated loading rates. Effluents from the primary clarifier, the following. t10st state standards allowed the trickling filter, and secondary clarifier were installation of either gravity flow filters or filtered to compare the difference in filter operation pressure filters. The majority of state agencies and performance when filtering different effluents. base the allowable hydraulic loading rate on Wastewater quality parameters used to monitor filter the type and configuration of media employed. The performance were biochemical oxygen demand (BODs) and majority of the design standards for wastewater suspended solids. filters permitted the following media types:- (1) sand; (2) anthracite; (3) sand and anthracite; The quality of filter influent affected the and (4) sand, anthracite, and garnet or ilmenite. quality of the filter effluent. Typical total BOD 5 All wastewater filter design standards called for and suspended solids removal efficiencies were 30 backwash appurtenances complete with air scour or percent and 75 percent, respectively. Soluble BODs mechanical scour. was not significantly removed by granular filtration.
iii TABLE OF CONTENTS
I NTRODUCT I ON . PURPOSE OF STUDY Specific Tasks Scope of the Study LITERATURE REVIEW 3 Introducti on 3 Theory 3 Filter Types . 3 Filter Rate Control 4 Filtration Rate 4 ~1edia and Depth 5 Headloss and Run Length 5 Filter Backwash .. . 5 Biochemical Oxygen Demand and Suspended Solids Removal 6 Influent Characteristics 7 Filter Design . 7 Pulsed Bed Filtration 7 RESEARCH PROCEDURES 9 Location. . 9 Filter Column Design 9 Fil ter r·1ed i a . . . • 9 Operation of Experimental Filters 10 Backwash. . . 10 Water Sampling and Analysis 10 RESULTS AND DISCUSSION 11 General 11 Influent Sources . 11 Influent and Effluent Relationship 12 Filter Media Performance 12 BODs and SS Removal . 12 Headloss Development 25 Backwash. . . 29 Filter Cycle Performance 30 BODs Equation • 30 Use of BODs Equation 31 FILTER DESIGN CRITERIA SURVEY 35 Types of Filters 35 Rate of Filtration . 35 11edia Type, Size, and Depth 35 Backwash . 35 Summary 35
SUMMARY 1 CONCLUSIONS 1 SIGNIFICANCE 1 AND RECOMMENDATIONS 37 Summary and Conclusions 37 Engineering Significance 37 Recommendations 38
LITERATURE CITED 39 APPENDICES 41 APPENDIX A: Filter performance data from pilot-scale study conducted at the Preston Wastewater Treatment Pl ant.. . . 41 APPENDIX B: Filter performance data from pilot-scale filtration study conducted at the Preston ~Iastewater Treatment Pl ant. Tabl es 12-26 are tabul ated results from fi lteri ng primary, secondary, and trickling filter effluents 45 v LI ST OF FIGURES
Figure Page Basic transport mechanisms in water filtration [Yao et aZ., 1971] 3
2 Net production rate versus filter rate for various run lengths [EPA, 1975] 4 3 Definition sketch for operation of downflow, granular-medium, gravity-flow filter [MetcaZf and Eddy, 1979] 6 4 Basic design of experimental filter column 9 5 Comparison of the mean total BODs concentrations in the common influent and the four filter effluents 13 6 Comparison of the mean soluble BODs concentrations in the common influent and the four filter effluents 13 7 Comparison of the mean particulate BODs concentrations in the common influent and the four filter effluents 14 8 Comparison of the mean suspended solids concentration in the common influent and the four filter effluents 14 9 Relationships between influent and effluent total BODs concentrations for each filter type at a hydraulic loading rate of 81.5 t/m2'min (2 gpm/ft2) 15 10 Relationships between influent and effluent soluble BODs concentrations for each filter type at a hydraulic loading rate of 81.5 t/m2'min (2 gpm/ft2) 16 11 Relationships between influent and effluent particulate BODs concentrations for each filter type at a hydraulic loading rate of 81.5 t/m2'min (2 gpm/ft2) 17 12 Relationships between influent and effluent suspended solids concentrations for each filter type at a hydraulic loading rate of 81.5 t/m2'min (2 gpm/ft2) 18 13 Relationships between influent and effluent volatile suspended solids concentrations for each filter type at a hydraulic loading rate of 81.5 t/m2'min (2 gpm/ft2) 19 14 Relationships between influent and effluent total BODs concentrations for each filter type at a hydraulic loading rate of 203.7 t/m2·min (5 gpm/ft2) 20 15 Relationships between influent and effluent soluble BODs concentrations for each filter type at a hydraulic loading rate of 203.7 t/m2'min (5 gpm/ft2) . 21 16 Relationships between influent and effluent particulate BODs concentrations for each filter type at a hydraulic loading rate of 203.7 t/m2'min (5 gpm/fe) 22 17 Relationships between influent and effluent suspended solids concentrations for each filter type at a hydraulic loading rate of 203.7 t/m2'min (5 gpm/ft2) 23 18 Relationships between influent and effluent volatile suspended solids concentrations for each filter type at a hydraulic loading rate of 203.7 t/m2'min (5 gpm/ft2) 24 19 Relationship between particulate BODs and suspended solids concentrations for both filter influent and effluent 26
20 Headloss development curves for all filters using secondary ~astewater as filter influent at a hydraulic loading rate of 81.5 t/m2'min (2gpm/ft2) 26 21 Headloss development curves for all filters USing secondary wastewater as filter influent at a hydraulic loading rate of 203.7 t/m2'min (5 gpm/ft2) 27 22 Headloss development curves for all filters USing trickling filter effluent as filter influent at a hydraulic loading rate of 81.5 t/m2'min (2 gpm/ft2) 27
vii LIST OF FIGURES (Contin~ed) · Figure Page 23 Headloss development curves for all filters using trickling filter effluent as filter influent at a hydraulic loading rate of 203.7 ~/m2'min (5 gpm/ft2) 28 24 Head10ss development curves for all filters using primary effluent as filter influent at a hydraulic loading rate of 81.5 ~/m2'min (2 gpm/ft2) 28 25 Headloss development curves for all filters using primary effluent as filter influent at a hydraulic loading rate of 203.7 ~/m2'min (5 gpm/ft2) 29 26 Variation of filter influent and effluent suspended solids concentrations during a filter run 30 27 The relationship between soluble BODs and total BODs of the filter influent 31 28 Graphical solution of Equation 7 to be used to predict filter effluent BODs as a function of influent total BODs and percent soluble BODs. 32 29 Relationship between filter influent and effluent BODs concentration from data collected and from calculated effluent BODs concentrations using the BODs equation 32 30 Relationship between filter influent and effluent from data collected by Dawda et aI. [1978] and from calculated effluent BODs concentrations using the BODs equation 33
viii LIST OF TABLES
Table Page Expected filter performance for trickling filter plants [EPA, 1974b] 7 2 Filter bed configuration and media parameters used for each filter column 10 3 Sewage strength of effluent from the primary, secondary, and trickling filter treatment process at the Preston Wastewater Treatment Plant. 11
4 Mean influent and effluent TBOOs , SBOD s , PBOOs, and SS concentrations and standard deviations for combined filtration data . 12 5 Results of statistical analyses testing difference between mean influent and effluent concentrations for each quality parameter and hydraulic loading rate 25
6 Calculated effluent TBOOs concentration using the BODs equation and TBOO s , SBOOs • and PBOO s concentrations from the fi ltration study conducted by Dawda et aZ. [1978] 33 7 Summary chart listing those states that responded to the filtration survey and the name of document containing wastewater filtration standards 36 8 Influent and effluent total BODs data from all filters for both loading rates tested. 42 9 Influent and effluent soluble BODs data from all filters for both loading rates tested 42 10 Influent and effluent particulate BODs data· from all filters for each loading rate tested 43 11 Influent and effluent suspended solids data from all filters for each loading rate tested 43 12 Influent and effluent volatile suspended solids data from all filters for each loading rate tested 44 13 Influent and effluent total BODs data filtering primary effluent for each filter type and 1oadi ng rate 46 14 Influent and effluent soluble BODs data filtering primary effluent for each filter type and load i ng rate 46 15 Influent and effluent particulate BOOs data filtering primary effluent for each filter type and loading rate 46 16 Influent and effluent suspended solids data filtering primary effluent for each filter type and loading rate 46 17 I nfl uent and eff1 uent vol at il e suspended soli ds fi ltering primary effl uent for each fil ter type and loading rate 46 18 Inf1 uent and eff1 uent total BODs data filteri ng trick1 ing fil ter effl uent for each fil ter tYPe and loading rate 47 19 Influent and effluent soluble BODs data filtering trickling filter effluent for each filter type and loading rate 47 20 Influent and effluent particulate BODs data filtering trick"ling filter effluent for each filter type and 1oadi ng ra te . 47 21 Influent and effluent suspended solids data filtering trickl.ing filter effluent for each filter type and loading rate . 47 22 Influent and effluent volatile suspended solids data filtering trickling filter effluent for each filter type and loading rate 48 23 Influent and effluent total BODs data filtering secondary wastewater for each filter type and loading rate 4B
ix LIST OF TABLES (Continued) Table Page 24 Influent and effluent soluble BODs data filtering secondary wastewater for each filter type and loading rate 40 25 Influent and effluent particulate BODs data filtering secondary wastewater for each filter type and loading rate 48 26 Influent and effluent suspended solids data filtering secondary wastewater for each filter type and loading rate 49 27 Influent and effluent volatile suspended solids data filtering secondary wastewater for each fil ter type and loading rate 49
x INTRODUCTION
The impact of pollution on society is now tlany existing secondary wastewater treatment recognized by nearly everyone, from the grade school plants cannot meet the minimum monthly average pupil to the highest officials in the land. Much of effluent standard of 30 mg/~ for suspended solids the pollution of our waterways comes from municipal and biochemical oxygen demand established by the and industrial sources that are controllable. Water Environmental Protection Agency in 1973. The quality and effluent standards are becoming more and addition of tertiary filters will enable many plants more strict. Removals of 80 or 90 percent of organic to produce a higher quality effluent and meet the loads and suspended solids will not suffice. Not standards for water quality limited streams. A only will virtually complete removal of organics and survey conducted in 1974 indicated that there were solids be required, but removal of specific substances only 77 operating U.S. tertiary filters treating to very low levels will be a necessity. The concept secondary effluents with a flow rate greater than of minimum pollution discharge from controllable 1135 cubic meters per day (m 3/d) [0.3 million sources is rapidly approaching. In most cities much gallons per day (mgd)J. Over 1500 plants will be progress could be made in controlling pollution by required to install tertiary filtration to achieve installing treatment processes now known. However, water quality standards estab"lished by the 1972 Act in many instances the best conventional treatment is [EPA, 1980]. not adequate for some of the present effluent quality requi rements, and most certai nly ~Ii 11 not be adequate The need for some form of tertiary treatment for future requi rements. As a genera 1 ph 11 osophy, to improve the quality of the effluents is likely effluent quality standards are being set on the basis to increase in the future as the volume of effluents of the best available treatment technology [Middleton discharged to inland waters continues to rise. and Stenburg, 1972J. Various methods of tertiary treatment are available, but the method that seems to find most application Filtration is one of the most important tertiary in large works is that of rapid gravity filtration processes in the implementation of the Federal Water [Tebbutt, 1971]. Filtration is used for the Pollution Control Act Amendments of 1972 and 1977. removal of suspended matter that may interfere with Since the passage of these Acts, there has been a subsequent treatment processes. Filtration may trend toward more stringent effluent standards, i.e., be necessary to meet usage requirements, including from the 30-30 (mg/~ biochemical oxygen demand and discharge to collection systems, ground waters, and mg/~ suspended solids) standard to the 10-10 or even receivinq waters rTahobanoglo~g and Eliassen. 5-5 standard for municipal effluents [Van Dyke, 1980]. 1970].
PURPOSE OF STUDY
The general objective of this research \vas to soluble biochemical oxygen demand, and suspended determine the effectiveness of constant rate, gravity solids removal by filtration. filtration in removing biochemical oxygen demand and 3. Comparisons were made on the operation and suspended solids from secondary treated municipal performance of four different filter designs. tlastewater and simulated secondary effluents. The 4. Design criteria were developed for each of results of this study will allow comparison of filtra the four filtration systems studied. tion with other tertiary treatment alternatives as a 5. A survey was conducted to review approval method of satisfying present and future water quality criteria and design standards for wastewater standards. filters employed by state regulatory agencies. Specific Tasks To achieve the general objective, the following Four different types and configurations of specific tasks were accomplished. granular media filters suggested by 1. Literature related to granular filtration of government agencies and commonly used in waste secondary wastewater was reviewed and evaluated. water filtration were studied. Filter operation 2. Experimental filter studies were conducted to and performance \vere mon itored and compa red for provide information on biochemical oxygen demand, each of the four filter configurations. LITERATURE REVIEW
Introduction particles overtake smaller particles, join them, and form still larger particles [Metcalf and Eddy, Water filtration is among the most widely used 1979]. Fluid shear. either turbulent or laminar, and extensively investigated processes in the field affects particle transport because velocity of environmental engineering [O'Melia and Stumm, differences or gradients can produce interparticle 1967J. Rapid filtration with downflow units has been contacts among particles suspended in the fluid used satisfactorily in the potable water treatment [OlMelia, 1980]. field for'many years, and most wastewater filter installations are similar to the filters used for The operation of rapid filters is affected by water treatment purposes. More efficient forms of a number of variables, some of which are considered filters, including mixed media beds and upflow units, at the design stage, and others which are signifi have been used with some success in both water and cant during operation. These variables are: wastewater treatment, but in most cases the conven (1) depth of media. (2) grain size of media, (3) tional downf10w unit is still adopted because of its grain material, (4) rate of filtration, (5) inflow simplicity [Tebbutt, 1971J. concentration. (6) type of suspension, and (7) water temperature [Ives and Sholji, 1965]. Filtration is accomplished by passing the wastewater to be filtered through a filter bed composed of granular material, with or without the addition of chemicals. Within the granular filter bed, the -- PARTICLE TRAJECTORY removal of suspended solids contained in the waste water is accomplished by a complex process involving ---- STREAMLINE one or more removal mechanisms, such as straining, interception, impaction, sedimentation, and adsorption. The end of the filter run (filtration phase) is A INTERCEPTION reached when the suspended solids in the effluent B SEDIMENTATION start to increase (breakthrough) beyond an acceptable level, or when a limiting headloss occurs across the C DIFFUSION filter bed. Ideally, both of these events should occur at the same time. Once either of these conditions is reached, the filtration phase is terminated, and the filter must be backwashed to COLLECTOR remove the material (suspended solids) that has accumulated within the filter bed [MetcaZf and EddY, 1979J. Theory I I The removal of suspended particles in a filter I I I / media is considered to involve two separ~te and I I distinct steps. First, the transport of,suspended I I particles to the immediate vicinity of the 1iquid I I I, I solid interface (i.e., to a grain of filter media or I I other particle retained in the bed), and second, the I I attachment of the particles [Jaa et aZ., 1971]. The suspended particles contact and become attached to the filter media through one or a combina Figure 1. Basic transport mechanisms in water tion of the following mechanisms: (1) interception, filtration [Jaa et at., 1971]. (2) sedimentation, (3) diffusion, (4) inertial momen tum, (5) flocculation, and (6) fluid shear or velocity gradients. Interception is the result of the particle Filter Types contacting the media because of its size. Sedimenta tion transport is a result of buoyant and drag forces There are several ways to classify filters. on the particle. Both of the mechanisms affect particles Th~y can be categorized according to the direction with sizes of one micron and larger. The smaller of flow through the filter bed, i.e., downflow. particles are collected on the media (collector) by upflow. bif1ow. radial flow. horizontal flow, diffusion where particles in suspension are bombarded , fine-to-coarse, or coarse-to-fine. Filters are by molecules of the medium. This is known as Brownian also classed according to the type and depth of movement of the particles. The first three transport filter media used as sand, coal, coal-sand, mechanisms are illustrated in Figure 1 [Jaa et al., multilayered. mixed media, shallow bed, or deep 1971J. Inertial impaction is the result of particles bed. Filters are also described by flow rate. contacting the media because heavy particles will not Slow sand filters operate at 2.0 to 5.3 liters per follow flow streamlines. Flocculation occurs when large square meter per minute (~/m2'min) [0.05 to 0.13
3 gallons per minute per square foot (gpm/ft2)], and Fil tration Ra te high rate filters operate at rates of 122.2 to 611.1 ~/m2·min (3 to 15 gpm/ft2). Investigations of filtration rate have demonstrated the effect of rate on effluent water Filters may operate with pressure or gravity flow. quality. Tehobanoglous and Eliassen [1970] have Gravity filters are built with an open top and shown that for a given sand size, varying the constructed of concrete or steel. Pressure filters filtration rate had little effect on the suspended are enclosed and ordinarily fabricated from steel in solids removal characteristics of the filter bed. the form of a cylindrical tank. Gravity filters In another study, effluent quality with media usually operate with 2.14 to 3.66 m (8 to 12 ftl of depths of 60.96 cm (24 in) was not significantly available head. Available head for a pressure filter affected by a flow rate up to 244.2 ~/m2'min (6 may be as high as 105 m (346 ft) [Culp and Culp, gpm/ft2) [Baumann and Huang, 1974]. In filtering 1974] . biological floc at reasonably low influent solids concentrations «30 mg/~), the effect on effluent Filter Rate Control quality of rates up to 408 ~/m2·min (10 gpm/ft2) is not very significant [EPA, 1975]. There are three basic methods for controlling the rate of flow through the filter. These methods \~ith un iform suspended soli ds concentra ti ons differ primarily in the way that the pressure drop and filtering characteristics, water treatment (driving force) is applied across the filter bed. filter efficiency is a function of the filtration These methods are: (1) constant-pressure filtration, rate and the influent solids concentration. In (2) constant-rate filtration, and (3) variable wastewater filtration, however, filtrate quality declining-rate filtration [Cleasby, 1969]. is less dependent on rate and influent suspended solids concentration , 1974a]. When operating under constant-pressure conditions, the total available pressure drop across the filter The rate of filtration determines the volume remains the same throughout the filter run. The rate of water that can be filtered daily. This rate of filtration is high at the beginning of the filter also affects the period of a filter run and run because the filter permeability is high. As the frequency of backwash which must be considered in filter becomes clogged with solids, the permeability economic comparisons. Figure 2 has been prepared decreases and flow rates drop [Webe~, 1972]. to facilitate a comparison of the net water production to filter run and run length [EPA, 1975]. In constant-rate filtration, a constant pressure drop is maintained across the filter system. The filter rate is held constant by means of a flow 10 ,...------" control valve. As filtration proceeds, the filter INFINITE RUN LENGTH clogs with solids and the flow control valve is HOUR R N NGTH' '0 HOUR RUN LENGTH opened slowly to maintain a constant rate of flow. 9 Constant-rate filtration may also be controlled by 8 HOUR RUN LE~"'GT-'-'H ___ht_H, splitting the influent flow equally to the operating Ii HOUR RUN LENGTH T P rON RAT AT Av AGE I filters by means of an influent weir box on either 8 LOADING AND 10 FT. TERMINAL HEADLOSS filter. The effluent control weir must be located above the filter media surface to prevent accidental dewatering of the filter bed. This arrangement eliminates the possibility of negative pressures in the filter and the need for a flow control valve. The only disadvantage of influent-flow splitting is w the additional depth of the filter box required Ii [Webe~, 1972]. IX Z The third method for filter operation is an gQ intermediate of constant-pressure and constant-rate 8 4 operation. Variable declining-rate operation is It similar to constant-rate operation with influent-flow !;; splitting but has one principal difference. As the z 3 filters served by a common influent header become clogged, the flow through the dirtier filters decreases more rapidly, causing the cleaner filters to pick up the capacity lost by the dirtier filters. The water level in all filters rises slightly as this happens, providing additional head needed by the cleaner filters as they receive the flow diverted from the dirtier filters. This method of operation causes a gradually declining-rate near the end of O~~--~~3--4L--L-~6-~1--~8~-9L-~,O the filter run. The advantages of variable declining FILTER RATE (GPMlSQ, FT,} rate operation over constant-rate operation include significantly better filter effluent quality. less required available head, and longer filter runs Figure 2. Net production rate versus filter rate [Webel" , 1972]. for various run lengths [EPA, 1975].
4 Media and Depth pattern. With surface cake filtration, the filtration is dominantly achieved by the cake The selection of the size and depth of filter itself, and filtrate quality is constant throughout media and the appropriate filtration rate are inter the run [EPA, 1974aJ. related. In general, filtrate quality is improved by the use of finer media, greater media depth, or lower Removal of the solids within the bed rather filtration rates. Similarly, headloss generation than just at the surface is termed depth filtration. rate is increased by finer media, greater media depth, Both surface and depth filtration usually occur and higher filtration rates. With some influent to some degree in any application. In suspensions, these generalizations may not depth filtration, headloss tends to build up hold. For example, in the filtration of linearly with time or with solids accumulation. secondary effluents, filtration rate has little effect For downflow filtration, the farther the solids upon filtrate quality over the usual range of rates penetrate into the bed, the slower will be the employed - 81.5 to 203.7 £/m2 'min (2 to 5 gpm/ft2). rate of headloss buildup, but the sooner the solids Increased media depth may not compensate for coarser will break through into the effluent [EPA, 1975J. media in achieving filtrate quality , 1974aJ. Depth filtration is employed by creating a coarse to fine particle distribution in the direction of flow. The size of filter media (0.55 to 0.92 mm) does not greatly affect effluent quality but does signifi The lengths of filter run are often governed cantly affect headloss development [Baumann and by the amount of available head. Depth filtration Huang, 1974J. It would seem that the suspended promotes longer filter runs because of the slower particles in the filter influent can be removed headloss accumulation. independently of filter particle size up to a grain size of about 1.0 to 2.5 mm [Tebbutt, 1971J. The length 0f filter run should be at least 6 to 8 hours to avoid excessive backwash water use, In multimedia fil ter beds, if the anthracite but less than about 36 to 48 hours to reduce layer is greater than 41 to 51 cm (16 to 20 in), anaerobic decomposition within the filter and media placed below the anthracite contributes little possible detriment to the effluent quality. The to overall suspended solids removal [Tahobanog~ous, desired run length can be achieved by selecting 1970J. Baumann and Huang [1974J diSCOvered that a either the terminal headloss or the filtration rate sand depth of 30.48 to 38.1 cm (12 to 15 in) beneath or both ,1974a]. Run length is the result of 30.48 to 38.1 cm (12 to 15 in) of anthracite was an interaction of two variables: filtration rate sufficient and greater media depths did not increase and the influent suspended solids concentration solids removal. [Baumann and Huang, 1974]. Granular filter media commonly used in water and Fi 1ter Backwa sh wastewater filtration include silica sand, garnet sand, and anthracite coal. These media can be Backwashing the filter is the process employed purchased in a broad range of effective sizes and to clean the filter bed. Usually this is accom uniformity coefficients. The term "uniformity plished by reversing the flow through the filter. coefficient" designates the ratio of size of grain Backwashing is performed at the end of the filter which has 60 percent of the sample finer than itself, run when the water level has reached terminal head to the effective size which has 10 percent finer loss or when the filtrate quality falls below than itself. ."Effective size" indicates the size of established criteria. Figure 3 is a sketch of a grain (in millimeters) such that 10 percent (by granular, downflow filter illustrating the weight) of the particles are smaller and 90 percent operation and backwash phases. are larger than itself. The media have specific gravities approximately as follows: anthracite coal, A sufficient flow of wash water is applied 1.35 to 1.75; silica sand, 2.65; garnet sand, 4 to until the granular filtering medium is fluidized 4.2 [EPA, 1975]. (expanded). The material that has accumulated within the bed is then washed away. The wash water Head10ss and Run Length . moving past the medium also shears away the material attached to the individual grains of granular Granular media filters remove suspended solids medium. In backwashing the filter, care should be in one of the following ways" (l) by finer media at taken not to expand the bed to such an extent that the top of the filter which form a relatively thin the effectiveness of the shearing action of the layer of deposited solids at the surface; (2) by wash water is reduced. In most wastewater treat removal of the solids within voids at depth within ment plant flowsheets, the wash water containing the porous media; and (3) by a combination of surface the suspended SOlids that are removed from the removal and depth removal. The more uniform the filter is returned either to the primary settling distribution of the solids throughout the depth of the facilities, or to the biological treatment process filter media, the better the use of the available [Metaa~f and EddY, 1979]. head [EPA, 1974a]. Surface wash, air-scour, and bed fluidization When solids are removed predominantly at the are modes of backwash employed especially for surface, rapid headloss develops and short filter wastewater filters. The relative effectiveness of runs are observed. In such cases, the headloss curve these methods of backwashing has been studied in (headloss versus time) will be exponential. Increasing detail. The following recommendations for back terminal headloss does not increase production per washing wastewater filters were presented by filter run significantly with this type of headloss C~easby et a~., [1975].
5 4. The use of air-scour auxiliary or surface wash auxiliary is essential to the satisfactory functioning of wastewater filters. These methods did not completely eliminate all dirty filter problems, but ~~ both auxiliaries reduced the problems to EHlvent le.vel ~ Washwater dlll1!'~ hltPllng acceptable levels so that filter function trough did not seem to be impaired. Waler !.:\ .... el -W=-'---~{------11 dUring backwa$hinp 5. Expansion of the coals and sands commonly specified in dual and mixed media filters is essential to their proper backwashing when USing either air-scour or surface wash auxiliaries. A minimum of 25 percent expansion of each media is
Dr.. ln C recommended under the most crucial warm season condition.
o Witih water 't--' 6. Special provisions are needed in the ~~,--,:E -"---'~-'----' t5 Con,rotter deSign and operation of air-scour systems. Drain How filtet oper"te$ Biochemical Oxygen Demand and 1, Open valve A, tThi'S .;lIows efiluent (0 flow to flherJ 2. Open valve a, {Thi1 aHows effluent to flow thfOVgh filted Suspended Solids Removal 3. During filter o~ratioJIII!I olhe, valvts are closed. HOW' filter 11 backwashed The variables that determine filter perform 1. Close ....alve A. ance fall into two major groups: influent "'} CI~ val .... r fI when water in filfer drops down to top of o .. erflow. 3. Open: v')/ves C and D. (ThIS allows water from wash watel tank 10 flow characteristics and physical characteristics of up through the filt~nng medIum. !ooit!rHng lip fhe sand and washing the accumulated rolid'!.lrom Ihe surtace of the sand. out of the filter. Filter the filter. Physical characteristics of the filter boIckwash water IS rerurnlold to head end of treatment plant. include size of media, depth of media, and hydraulic How 10 finer to waste hf used) 1, Open val .... es A and E. All olhH valves clnsed. Effluenl is $ometim~s loading rate. Influent characteristics are Hte'ed to waste for 11 few minute:Hlftet filtef has been wa$hlld to condltioo (he filter before ill~ Put intQ $li!fvicc suspended solids (5S) concentration, strength of floc, and biochemical oxygen demand (BODs) concen tration. Suspended solids removal efficiencies of secondary effluent using granular filtration range Figure 3. Definition sketch for operation of down from 60 to 90 percent, Expected effluent SS from flow, granular-medium, gravity-flow filter multimedia filtration is 10 to 20 milligrams per [Metaalf and Eddy, 1979J. liter (mg/~). The SS removal efficiency does not change significantly at loading rates below 408 ~/m2'min (10 gpm/ft2) [EPA, 1975]. 1, The cleaning of granular filters by the upward flow of water alone to fluidize the Total biochemical oxygen demand (TBODs ) filter bed is inherently a weak cleaning method consists of particulate (PBOD s) and soluble BODs because particle collisions do not occur in a (SBOD s). The removal of particulate BODs is fluidized bed. This weakness was clearly related to SS removal. The filter primarily demonstrated during wastewater filtration removes only suspended matter, and the effective studies where the filter that was washed by ness of the filter should be related to SS removal. water fluidization alone developed serious Other parameters such as BODs. chemical oxygen dirty filter problems such as floating mud demand, etc., may be considered. but they are balls, agglomerates at the walls, and surface removed mainly in proportion to the suspended cracks. These problems were observed when solids removed. Biological activity, which occurs filtering either secondary effluent or in the media bed, will tend to remove some soluble secondary effluent that had been treated with BODs, but this is not predictable [Walters, 1979J. alum for phosphorus reduction. Dawda et al. [1978J concluded that effluents 2. Heavy mud ball accumulations are containing less than 10 mg/~ of BODs and SS can be undesirable because they contribute to produced by granular media filtration when a good higher initial head losses and shorter filter quality secondary effluent «30 mg/~ of BODs and cycles. They may also cause poorer filtrate SS) is applied to the filters. During Dawda's quality in some cases. study, S5 removal ranged between 70 and 80 percent, and TBOD s removal ranged from 30 to 60 percent 3. Filter cracking, which is a sign of most of the time. compressible coatings on the filter media, allows deeper penetration of solidS into The variable nature of the suspended sol ids the filter and may cause poorer filtrate present in final settling tank effluents make quality in some cases, although quality predictions of the performance of any form of detriment was not demonstrated in this tertiary treatment difficult, but it is generally research. The cracking and deeper penetration assumed that rapid gravity filters if loaded at of sol ids. reduces the rate of head loss about 139 ~/m2'min (3.4 gpm/ft2) remove 70 to 90 development in the surface layer but increases percent of the applied suspended solids [Tebbutt, it in the deeper layers of the filter. [1971] .
6 Tertiary granular media filters are designed instances when the SS concentration changed by a primarily for removal of suspended solids and the factor of 2 within an hour. The random nature of BODs associated with suspended solids. However, suspended solids in the effluent from final removal of soluble BODs occurs to some extent due to settling tanks and from tertiary treatment units bacterial activity within the filter media [EPA, makes it almost impossible to comply with a 1980] .. standard with 100 percent confidence [Tebbutt, 1971]. A comprehensive study was conducted on full-scale Another factor that affects the character of tertiary filters at eight treatment plants. [--lean secondary effluents is chlorine. Chlorination of filter influent total BODs varied from 9 to 44 mg/t secondary effluent modifies the filterability of at the eight plants, and mean effluent total BODs the effluent from an activated sludge plant. The varied from 3 to 25 mg/t. Average secondary effluent filtration efficiency of chlorinated water was suspended solids concentrations varied from 25 to 62 decreased, but the rate of head10ss increase was mg/t and filter effluent suspended solids concentra lower. The change of floc size, density, and floc tions from 5 to 20 mg/t [EPA, 1980]. Soluble BODs strength all are responsible for the change in tests were conducted USing filtrate from a standard filter performance. The floc in the chlorinated glass fiber filter. Soluble BODs removal was effluent appeared to be smaller, lighter, and more reported at 30 and 44 percent for some plants. This fragile than that in the unchlorinated effluent soluble BODs removal was probably attributable to [Hsiung, 19$0]. biofilms attached to the filter media serving as adsorption sites for some components of the non Filter Design colloidal organics [EPA, 1980]. An optimum design is achieved when all the Typical suspended solids and BODs removals available head is exhausted in a filter run at the obtained by filtering trickling filter effluents same instant that SS begin to pass through the are shown in Table 1. filter in excess of the desired effluent quality. It'is difficult to produce an optimum design The single most important factor affecting filter because the present level of filtration theory can performance is the quality of seconda ry effl uent only semi-quantitatively account for the inter produced by the biological treatment. If good dependence of the design variables [Baumann and performance is exhibited by the biological treatment Huang, 1974]. Because of the variable nature of system, good filter performance can be expected. effluent qual ity and the difficulty in predicting Conversely, if the biological facility is faulty, hydraulic capacities of a filter, it is essential filtration will be more difficult and less successful to conduct a pilot-plant study for at least 12 [EPA, 1974b] . months to approach optimum economic design [Tebbutt, 1971; and Baumann and Huang, 1974]. Influent Characteristics The characteristics of wastewater solids Pulsed Bed Filtration governing filter performance are determined by the treatment processes ahead of filtration. In direct In conventional single-medium sand filters, filtration of secondary biological effluent, the most of the solids are removed at or near the residual solids applied to the filter are predominantly surface of the sand bed forming a layer of solids. biological floc grown in the treatment process [EPA, As a result, head10ss accumulates very rapidly, 1975]. Biological flocs are stronger and more the filter run is short, and a large portion of resistent to shear than chemical flocs from alUm or the filter bed is not utilized for solids storage. iron coagulants [Tchobanoglous and Eliassen, 1970]. Dual and multi-medium filters are used to achieve greater solids penetration into the filter bed The variability of the quality of effluent from resulting in longer filter runs. Despite the the secondary process is also an important factor advantage of longer filter runs, multi-medium in filter design. Tebbutt [1971] reported several filters require more stringent media specifications
Table 1. Expected filter performance for trickling filter plants [EPA, 1974b].
Percent Soluble BODs Removed in Secondary Process
85 percent 80 percent
Filter Fl1ter Filter Filter Inf1 uent Effl uent Inf1 uent Effluent BODs SS BODs SS BODs SS BODs SS mg/1 mg/! mg/! mg/1
20-40 20-40 20-30 15-20 40-50 35-45 30-40 20-25 Run Time (hr) .: 6-11 Run Time (hr) = 5-9
7 and larger volumes of backwash water. accumulate within the sand bed, clogging pores and reducing run lengths. The mild detergent and In pulsed-bed filtration, intermittent air pulsing bleach solution is effective in removing the grease of the filter bed is employed to loosen and mix solids and biological slime within the surface layers retained in the surface layers of the filter. The restoring the sand to its original condition. air-pulse action moves the solid material deeper into the sand bed and decreases the rate of headloss Because the single-medium filter employs an buildup allowing longer filter runs. Average run air-pulse system and chemical cleaning cycle, the lengths were increased by more than four times as a filter can successfully be used to filter primary result of the air-pulse system. The pulsed-bed filter effluent. The air-pulse filter operation was features a semi-automatic chemical clean cycle. Over developed by Hydro-Clear [Matsumoto et at., 1980J. a period of time, grease and biological slime will
8 RESEARCH PROCEDURES
Location LEGEND The pilot plant study was conducted at the Preston A AIR INLET City Wastewater Treatment Plant, Preston, Idaho. The B FILTER INFLUENT current population of Preston is approximately 3600 C BACKWASH EFFLUENT people. The complete treatment process includes D FILTER EFFLUENT primary treatment, secondary treatment, and chlorine E BACKWASH INFLUENT disinfection. The secondary treatment consists of a F MEDIA single stage, standard rate, trickling filter. There G MINIMUM WATER DEPTH is one unit for each of the trea tment processes. The H NORMAL WATER DEPTH design flow rate for the Preston plant is 3785 m3 /d Z VALVES (1 mgd). The average flow was approximately 3028 m3/d (0.8 mgd) throughout the study period. A portion (33 percent) of the wastewater flow comes from infiltrat~on into the sewage collection system. This problem is most serious during the summer months and tends to dilute the strength of the sewage. Wastewater flow charts at the Preston plant indicate infiltration flow H rates were as high as 1136 m3 /d (0.3 mgd) during the study period. s' Z Filter Column Design Z The experimental filter operation consisted of four 15.24 cm (6 in) diameter filter columns. Each column consisted of a plexiglass base 1.23 m (4 ft) G in length and a top portion constructed from 2.13 m -D (7 ft) of PVC pipe. The clear plexiglass base was used so that the filter media could be observed during operation of the fil ters. Winqow slots were construc ted in the PVC pipe section so that water depth could be observed and measured. The available head above the media surface was 2.44 m (8 ft). Filter effluent was discharged at the same elevation as the minimum water depth; therefore, headloss across the filter media was equal to the height of water above the filtrate outlet. This arrangement provides a method for immediate headloss determination, a constant rate of filtration without rate control devices, and eliminates the possibility of negative head in the filter and air binding due to gases coming out of solution that result from a Figure 4. Basic design of experimental filter negative head [Cleasby, 1969]. A diagram of an column. experimental filter column is shown in Figure 4. Inlet and outlet arrangements for both filter operation and backwash modes are illustrated. anthracite coal, sand, and garnet layers; (2) a dual media with anthracide coal followed by a layer The filters were operated at a constant flow of sand; (3) a dual media formed by covering garnet rate. The flow rate was controlled by a distribution sand with a layer of silica sand; and (4) a sand box placed above the filters, and wastewater was fil ter. pumped to the box and distributed to the four filters. A constant water flow was maintained by four V-notch Each of the filter beds was supported by a weirs (one for each filter column) which could be shallow gravel layer. The filter media and gravel adjusted to achieve the desired loading rate. 'were obtained from Neptune ~licrofloc. A FLEXCLEAN, plastic nozzle with small outlet slots was used Filter Media for the under drain. The plastic nozzle was obtained from EmCO, Salt Lake City, Utah. Four different filter bed configurations were placed in the filter columns. Silica sand, garnet The uniformity coefficient, effective size, sand, and anthracite coal, all of which are commonly and specific gravity for each media and overall used in wastewater filtration, were used as the filter bed depth are presented in Table 2. filter media. The four filter media configurations were as follows: (1) a mixed media, consisting of
9 Table 2. Filter bed configuration and media parameters used for each filter column.
Configuration and Type of Filter Media Media Parameters Mixed Coal- Sand- Sand Sand Garnet
Top Coal Layer (Anthracite) effective size (mm) 1.0-1.1 1. 0-1. 1 uniformity coefficient <1. 7 <1. 7 depth (cm) 38 46 specific gravity 1. 6-1. 65 1. 6-1.65 Central Sand Layer effective size (mm) 0.4-0.55 0.4-0.55 0.4-0.55 0.45-0.55 uniformit~ coefficient <1.8 <1.8 <1.8 <1.8 depth (cm 38 30 38 76 specific gravity 2.6±0.5 2.6±0.5 2.6±0.5 2.6±0.5 Bottom Layer (Garnet) effective size (mm) 0.2-0.29 0.2-0.29 uniformity coefficient -- -- depth (cm) 15 22 specific gravity 4.0 4.0 Tota 1 Depth (cm) 91 76 60 76
Operation of Experimental Filters aspirator was" also used to mix air with the back wash water which allowed an air-scour with water Loading rate, influent SS, and influent BODs backwash. Backwashing usually lasted 10 to 15 were each varied during the test period. The loading minutes for each filter. The filter bed normally rate was varied by adjusting the weirs in the distri expanded 50 percent during the water backwash.' bution box. The influent water quality (SS and BODs) was varied by changing the source of the water. Water Sampling and Analysis Effluents from the secondary clarifier, primary clarifier, and trickling filter were used either Water quality analyses were performed on the singly or mixed as necessary to provide different common influent and the four filter effluents. filter influent water qualities. The hydraulic Samples were analyzed for suspended solids, volatile loading rates studied were 81.5 and 203.7 ~/m2'min suspended solids, soluble BODs. and total BODs (2 and 5 gpm/ft2). Chlorine residuals were not according to procedures outlined in "Standard measured in any of the three water sources. rlethods for the Examination of Water and Wastewater" [APHA, 1975; and Cowan et al., 1978J. Soluble Backwash BODs was measured using the filtrate obtained when the water was filtered through a Whatman GF/C The filters were operated continually five days glass fiber filter. Composite samples were of the week, and were backwashed every 24 hours or collected manually during the filter cycle~ Sample when excessive head10ss developed. Potable water was frequency was either hourly or based on percent of used for backwash water. The backwash inf1 uent 1i ne filter cycle. The composite sample consisted of a contained a venturi-aspirator which was used to minimum of four, equal-volume, grab samples. When introduce a chlorine solution into the backwash water. sampling on percent of filter cycle, samples were The purpose of the chlorinated backwash was to taken at 0 percent, 30 percent, 60 percent, and control any bacterial growth and slime on the media 100 percent time intervals of the filter cycle. surface. Such growth causes rapid headloss develop Particulate BODs was determined from the difference ment and inhibits effective filter operation. The between total BODs and soluble BODs.
10 RESULTS AND DISCUSSION
General of each source were calculated by averaging composite filter cycle samples of the common filter influent. Four different granular media configurations were evaluated as to their effectiveness as a tertiary The low TB00 5 and SBOOs concentrations wastewater treatment process. The characteristics measured in the primary clarifier effluent are of the filter influent and effluent were analyzed and indicative of dilute sewage. Sewage is considered the results are shown graphically in the following dilute when contaminant concentrations are secti ons. consistently below the typical range. Typical total BODs concentrations of domestic primary The four media are compared as to their effective effl uent range from 80 to 200 mg/9. [Metcalf and ness in removing suspended solids (SS). total bioche EddY, 1979J. The average organic load to the mical oxygen demand (TBOOs). soluble BODs (SBOOs), treatment plant is low because of infiltration and particulate BODs (PBOO s). Headloss development into the sewer system. for each filter is presented for each hydraulic flow rate. The different characteristics and filter Filtering primary water proved unfeasib'le operation of the three filter influent sources were because of rapid headloss development, especially filter backwashing and filter cycle performance. at the 204 9./m2·min (5 gpm/ft2) loading rate. At the lower loading rate, the coal filters operated A mathematical equation was developed to calcu up to eight hours. The primary water contained late total biochemical oxygen demand removal by the fibrous solids which would quickly blind the media filters. The equation was used with BODs removal surface. A surface mat was formed by solids on data obtained with the experimental filter columns both the sand and coal media. This solids mat operated at the Preston Treatment Plant. would break up during backwash, and inter-mix with the media. The air-scour backwash was effective Influent Sources in breaking up the solids mat into sufficiently small particles for removal. In order to Filter influent was collected from three successfully filter primary effluent using a different sources at the Preston Treatment Plant granular media filter, effective backwash must be during the study. Effluent wastewater from the assured and a method be employed to increase run primary clarifier, trickling filter, and secondary length. The air-pulse filter operation may be clarifier was pumped to the experimental filters for such a method [Irwin and Garzonetti, 1980; and fil tration treatment. t,lean concentrations of TBOO s, Matsumoto et al., 1980]. SBOOs, PBOO s, suspended solids (SS), and volatile suspended solids (VSS) for the three sources of The average suspended sol ids concentration in wastewater are I isted in Table 3. '·lean concentrations the trickling filter effluent was the same value as the solids concentration in the secondary effluent. Filtration of trickling filter effluent did not cause filter operational problems, and the solids captured in the filter bed were readily Table 3. Sewage strength of effluent from the removed by normal backwash procedures. primary, secondary, and trickHng fi lter treatment processes at the Preston Waste Although the gravimetric measurement of solids water Treatment Plant. from the secondary and trickling filter effluents resulted in equal solids concentrations, the characteristics of the solids were different. Wastewater Source Solids associated with the trickling filter effluent appeared larger than the secondary floc. Effluent from the trickling filter contained small flies, Trickling worms, snails, and other biota scoured from the Quality * Primary Filter Secondary trickl ing filter media. The large floc 'and biota Parameter Eftl uent Effl uent Effl uent were captured at the media surface resulting in rapid increase in headloss. Direct filtration of Total BODs (mg/9.) 36 24 17 trickling filter effluent could feasibly be implemented at the Preston plant by using a larger Soluble BODs (mg/9.) 15 11 8 sized coal which would enhance in-depth filtration Particulate BODs (mg/9.) 21 13 ' 10 and increase the length of filter run. Suspended Solids (mg/9.) 25 16 16 Filtration of secondary settled effluent Volatile Solids (mg/9.) 16 8 7 provided the longest filter runs. In-depth filtra tion 'was achieved in the coal-layered filters. * All values are average filter-cycle composites and I·lost of the sol ids were captured in the top coal due to rounding errors, totals may differ. layer. Longer backwash was necessary to clean the
11 filter bed because the solids would adhere to the coal Table 4. Mean influent and effluent TBOD s, SBOO s , media. Tables 12-26 in Appendix B contain filter PBOD s, and SS concentrations and standard performance data for each of the three sources of deviations for combined filtration data. wastewater. Fil ter Type Influent and Effluent Relationship Fil ter Wastewater 2 3 4 Filter effluent BODs (total, soluble, and parti Parameter Infl uent culate BODs), suspended solids, and volatile suspended (mg/£) Filter Effluent (mg/£) solids concentration were plotted versus influent concentrations for each filter. A linear relationship was found to exist between the filter effluent and TOTAL BODs influent water quality concentrations. This relation Average * 24.2 16.116.315.916.1 was observed for each wastewater quality parameter Std. Oev. ** 9.5 6.8 6.4 6.5 6.8 examined. SOLUBLE BODs The linear relation between influent and effluent Average 10.6 9.6 9.4 9.0 9.2 qualities indicates that the effluent quality is Std. Oev. 4.7 4.6 4.4 4.8 4.7 highly dependent on the quality of the filter influent. This condition supports the statement that the single PARTICULATE BODs most important factor governing filter performance is Average 13.7 6.6 6.9 6.9 6.9 the quality of the secondary effluent produced by the Std. Oev. 5.8 3.1 3.1 3.1 3.7 biological treatment process [EPA, 1974b]. SUSPENDED SOLIDS Fil ter t1edia Performance Average 18.1 4.7 5.1 4.7 4.7 Std. Oev. 5.7 3.1 3.0 2.8 3.0 The four filter beds were composed of different granular media configurations. The coal-sand-garnet bed had a total depth of 90 cm (36 in). The depth of * Number of samples = 30 for all tests the sand-garnet bed was 60 cm (24 in). Both the ** Std. Oev. = standard deviation coal-sand and all sand beds had a total depth of 76 cm 1 coal-sand-garnet (30 in). The characteristics of the media were 2 coal-sand presented in Table 2. 3 sand-ga rnet 4 all sand t1ean filter influent and effluent concentrations of TBOO s, SBOO s, PBOO s, and SS were calculated from combined data of both flow rates and three water BODs and SS Removal sources. Mean concentrations, number of samples, and standard deviations are listed in Table 4 for each Total biochemical oxygen demand consists of of the four filters studied. A comparison of the a soluble portion and a particulate portion. common influent wastewater qualities and the four Removal of either portion decreases the concentra filter effluent qualities is shown in Figures 5-8. tion of total BODs. Particulate BODs removal is There were no significant statistical differences associated with suspended solids removal. Soluble (95 percent confidence) in the effluent TBOO s, SBOO s, BODs removal is caused by biological activity, PBOO s, and SS from any of the filter media configura adsorption, or ion exchange within the filter bed. tions. A statistical analysis of the difference Figures 9-18 are a series of linear plots of between two population means was performed to filter influent versus filter effluent concentrations. determine if the mean influent and effluent concen These linear plots show that the effluent quality trations for TBOO s, SBOO s, PBOO s, SS, and VSS from the four filters studied is directly related differed [Ott, 1977]. The average effluent concen to the influent quality. The effect of the filter tration was calculated using all four filter media on the effluent quality is represented by the effluents. The statistical test was performed for slope of the linear relationship. As the slope both loading rates. The results of the statistical increases, a decrease in performance is indicated. analyses are presented in Table 5. Conversely, an improvement in performance is indicated by smaller slopes. If the slopes of the 1 inear The student's-t values for four of the five relationships between influent and effluent for two qua 1 ity pa rameters were greater than the 99 percent filter types are equal, then the performance of each test statistic. Therefore, the mean effluent filter is equal. concentration was significantly less than the mean filter influent at both hydraulic loading rates for A statistical test of the difference between two total BODs, particulate BODs, suspended solids, regressions are performed to determine the signifi and volatile suspended solids. In contrast, the cance of the difference between slopes [SteeZ and soluble BODs mean influent and effluent concentra Toppie, 1960]. At the 95 percent confidence level tions did not" differ at the 95 percent confidence no two slopes were different for anyone quality level for either loading rate. Although the stu relationsilip. Therefore, there was no statistical dent's-t value for the comparison of soluble BODs difference (85 percent confidence) in the removal of removal of the lower loading rate was within 0.001 of BODs and SS by any of the filter types evaluated. being significant, error inherent in the BODs test
12 J
0 0 0 ci I"l FILTERS I"l 1 cooL-sand-gar net net 0 2 cooL-sand 0 1.0 3 sand-garnet N 4 aLL sand K1
...... ) ~o ...... ) . ,~ ,~m ~~ e ...... w 0 0 00 o 0 . a::l • a::l~ 1.0 W ..J ..J CC a::l f:- :::J 00 ..J o f:-. o· 8 (/18
0 0 1.0 tri
0 0 0 ci INF EFFl EFF2 EFF3 EFF4 I EFFl EFF2 EFF3 EFF4 INFLUENT AND EFFLUENT INFLUENT AND EFFLUENT
Figure 5. Comparison of the mean total BODs concentrations in the Figure 6. Comparison of the mean soluble BODs concentrations in con~n influent and the four filter effluents. the common i nfl uent and the four fil ter effl uents. J
0 o ci o I"'l PILTERS I"'l FILTERS 1 coal-sand-gar nel 1 coal-sand-gar nel 0 2 coal-sand o 2 coal-sand Lti 3 sand-garnel 3 sand-garnel N 4 aLL sand Kl 4 all sand ..J ..J "- "-mo m E . EO ~ 0 ~ci N N if) 0 o 0 ...... p- al ....J w~ 0 0 E- 0 o Lti Lfl 0 o ci o n n n n INf EFFI EFF2 EFF3 EFF4 INF EFFI EFF2 EFF3 EFF4 INFLUENT AND EFFLUENT INFLUENT AND EFFLUENT Figure 7. Comparison of the mean particulate BODs concentrations Figure 8. Comparison of the mean suspended solids concentration in the common influent and the four filter effluents. in the common influent and the four filter effluents. .", _. , 't '" ~ iii'" ~ola{gpm/sqft)=2.0 o ~ola!gpm/sqfl)=2.0 ~ Equal eon of lene: ...~ [quoleon of L~ne: Y = mX + b Y = mX + b ,0~ m =0.562 mo m =0.605 a e'" b 2.3 b 1. 9 CJO CJ" r = 0.81 CJ.n 0.81 f5~ CON -' -' c, 0.0 5.0 10.0 15.0 2(}.0 ~5.0 30.0 35.0 10.0 45.0 SO.O SS.O u.!l 5.!l 15.0 .0.0 25.0 10.0 35.0 10.0 15.0 50.0 0;5.0 INflUENT TOTAL 800 (mg/ll INflUENT TOTAL 800 [mg/LI 01 iii" iii RoLe(gpm/sqft)=2.0 Role (gpm/sqfll=2.0 iii Equoleon of lena: ...~ Equoleon of lene: Y = mX + b Y = mX + b ,0~ m =0.175 0'0 m =0.562 E r· b i.7 b 2.8 CJ" CJO ,.. = 0.8i OLti r = 0.87 g~ c:JN -' -' <> SAND-GARNET .n ALL SAND __ +--r-~---'--,--'--'--'--'--.r--r-.r--r-r--r-r--r-'-I --;---,-----,----, O~~~-' r-~-'--.~ __r-~-'--'-'~'-'- __-'-' __ ~_'-·_r_ ,..~ ~ Q lO.D 15.0 20.0 ~5.0 30.0 35.0 10.0 is.!.'! ~:j.(l 55.!! O.C 5.0 10.0 15.0 20.0 25.0 30.0 INflUENT TOTAL BOO (mg/l INflUENT TOTAL BOD (~g/l) Figure 9. Relationships between influent and effluent total BODs concentrations for eaoh filter type at a hydraulic loading rate of 81.5 ~,fm2·min (2 gpm/ft2). """ . J .. C"> '"r g Ratelgpm/sqft)=2.0 Ralelgpm/sqfll=2.0 Equal,on of L~ne: Equal~on of L~ne; -.,; -ui -'N Y = mX + b -'N Y mX + b " " m =1.009 en m ! E =1.0~3 '" b -1.8. o o . b -2.2 8!i'ico r 0.84 o !Ii r 0.86 w coo.J oj! ::::Jui ~::::Jui ...Jo A'" -'- A '" til '" A/A ~ci::::J- !z01!~2 .J "- "- A A ~ '" A ui COAL -SAND-GARNET W : ) A COAL -SAND '"";+---r--'---r--'---r-~---r--~--r--' .,; ! , , l2.0 l6.0 21.0 30.0 0.0 6.0 l2.o 16.0 21.0 30.0 INPLUENT SOLUBLE BOD ("'gIL) INPLUENT SOLUBLE BOO (mg/L) Iii'" g'" 0'1 Ratelgpm/sqfl)=2.0 Rale(gpm/sqfLl=2.0 EquatLon of Lene: Equotcon of Lene: ::;lI,j Y = mX + b ::gj Y = mX + b " " en .. =1.011 Ol m =1.089 e ..!! b -2.5 b -2.9 0 '" o '". ON0 o !Ii co r = 0.86 co r = 0.91 W :J A '"";+---.---'---.---.---r---r---r-~r--.---. ";+---i~-'---..,----;-...... ----r---.--""----'---' 0.0 0.0 6.0 !2.0 INPLUENT SOLUBLE BOO (mg/Ll INPLUENT SOLUBLE BOO (mg/ll Figure 10. Relationships between influent and effluent soluble BODs concentrations for each filter type at a hydraulic loading rate of 81.5 t/m2·min (2 gpm/ft2). J o 1i! ;j! RoLe{gpm/sqfLj=2.0 RaLe(gpm/sqftl=2.0 .,; --->,., EquaLcon of Lcne: -~ Ill-on of Ll..ne! , ~~ 01 Y = mX + b 01 = !!IX + b Eo -0 m =0.258 .!:'" m =0.359 0'" o!ii "'",0 b 4.1 Cl b 3.2 1..1"; r = 0.49 "'"w.,; r 0.72 1-'"a: .....a: '" -' 5C! :;)0 Wo ~~ I--'" ..... !L 0:0 Q...,; '"0...,; ...... Z Z - 1..10 ::::J. ~c:-,,, "- L..- -'''"- 1..1" b o .,; a COAL -SAI'I)-GARRET .,; o '"0 0+1--~--r-~--'---r--.--.-~r--.--.-~r-~" 0.0 a.n 12.0 18.0 2i.O :lO.O 35.0 0.0 6.0 12.0 16.0 2i.0 30.0 31;.0 INflUENT PARTICULATE BOO {mg/LJ I NflUENT PART I CUlATE BOD {mgf Ll --' " ;j!'" "g Role {gpm/sqfLJ=2. 0 o ROLe{gpm/sqfll=2.0 " ::::;u-l :;~, Equalcon of lena: ,'" EquoL 0'" o+---'---.---~--r---r-~~-'--~--~--~---r--~" ~.a E.!} 12.0 IS.C 21.0 30.0 3& 0 0.0 6.0 12.0 ,8.0 ~1.0 30.0 3[.0 .. INflUENT PARTICULATE BOD (mg/L INflUENT PARTICULATE BOD ("'giLl gure 11. Relationships between influent and effluent particulate BODs concentrations for each filter type at a hydraulic loading rate of 81.5 2/m2·min (2 gpm/ft2). J ~ '"~ , m =0.145 '-" '-" 2 0 b -3.6 -,0 3d 0'" 0'" r = O. '3] '-" U'l a a ~c: ~~w- z'" IL w- '-" i}; :::l '-"0 :::l ..... 0 "'0 z- .....z- ci W :::l .. .. --' 3 ,,-0" ,-'"' Won Won .. • COAL-SAIIl> " . 0~1~~~~~~~~~, 6+-~--,--r--r--r--'" __-r-' __ .-~--'--.--.--.--'--' 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 '0,0 0,0 5.0 10,0 15,0 20,0 25,0 30,0 35,0 .c.o INfLUENT SUSPENDED SOLIDS [mg/ll I NfLUENT SUSPENDED SOL! OS I"'g/ LJ ...... co o g ~ ,0...> mon EN '-" 0 '-" :;00 b -2.8 20 ON r 0.83 a~ '-" '-" o l:Jo o zon ::s~ w -. w-z'" i}; i}; :::l '-"0 :::l ..... 0 "'0 Z .....z 6 W L.J :::l ":;J " .. ,,-0~ to-' Won Won ...... ALL SAND ci~'-.~~~-r-'~ ci+--.------.--.--r-'" 0,0 5,0 10.0 15,0 20,0 25,0 30.0 35.0 'O.D D.D 5,0 10,0 15,0 20.0 25.0 30,0 35.0 iIl,Q INfLUENT SUSPENDED SOLIDS Img/ll INfLUENT SUSPENDED SOLIDS (~'3/l1 Figure 12. Relati between influent suspended solids concentrations for each filter type at a loadino rate of n (2 gpm/ft2). J C> cij Roteigpm/sqfll=2.0 Rocelgpm/sqfcl=2.0 EquotLon of Lene: 3:'- . Equal,on of Lene: 0'1l ~ o ~ Rolelgpm/sqfll=2.0 Rolelgpm/sqfll=2.0 Equaleon af Lene: Equalcon of Lene: 0:1 -' " Y = mX + b "m~ Y = mX + b t~, E m =0.470 "' =0.356 '"~ RaLelgpm/sqfLI=5.0 o. RaLe(gpm!sqfLI=5.0 '" Equ~L~o~ of LLne" ~ EquoL~on of L~ne~ Y = mX + b Y mX + b b " =0. ',31 m =0.610 b -0.4 b 1. 4 _~ \"'1 0.96 oc; ~:-'1 0", r = 0.93 {DN o ...J o i~ o ~+--r~r-,--r--r-.--.--.-,--.--.-'--.--.-'--.--.-.--.--r--r-. ci" ::'.'1 S.O 10.0 15.0 20.0 25.0 30.0 35,0 10,0 55.0 0,0 5,0 10,0 15.13 20.0 25.0 ,]O.Q 3'5.0 10,0 .S.O 50.0 SS.!i INflUENT TOTAL BOD Img/LJ INflUENT TOTAL BOD [mg/LI N o ~ o "~ =5.0 R"Le(9pm/sqftl=5.0 " a ~ lil...on of U .. ~e: :Ii E~uoLc~~ 0f Lena: mX + b Y mX + b -' m =0.661 m =0.563 b b -0.4 0'" ....."'Iu-i r = 0.90 / a"! r = 0.92 <....:I'" g\!1 :PI;' 0 Ifo t-u I-ci ;::~ /0 ....ON o 0 " 0 r:;-e: .....zui " o t.:~ 0 w_ :::> :::> " .J 0 ...J L C'I " n/ L..c L, 0 tis o o " 0 '".; .,; SAND-GARNET / ALL SAND '"ci Ci~~~~~~::;JJ S.I) 10, Ij .IS.C, 20.0 25.0 10,n 1S.C 10 G 'is.Q 5C 'J 5S.G 00 C.O 10.t.! lS,Q Z!),I) 25.C ~o 0 15.1 1C,G 1S.0 50.0 55.0 INflUENT TOT~l BOO !mg!LI INfLUENT TOTAL BOG Img/LI re 14. Rel at; between i concentrations for each filter type at a hydraulic load; rate of 203.7 n (5 •• ... " P."l"l:lpm/sqfc)~5,O :1 r-oteI3pm/sGrl)~5.0 ~ EquOl,o~ ~r Lc~~: EqWOlLon ~f LLne: y ~ mX '" b 2 :J Y mX + b '" ~fJ 8fl6 ",J ~C.31'i E.?2 I "' b 0.7 b 1.2 Se r = 0.96 ~o ~j r O.:l6 er(.. A g~ w L.j <::lC>-' ::..)ci ..::>as-'~ " l' dC~ Ii l' ')0 o ....zU" '" ~~ 66 i:-111'i w A A ::J AA t>/ -'0 t:~ A L- ' ",-0 ~L-~ -1 w- t..j A 4~ A hA A COAL-SAND-r,ARNET '" o Y A COAl-SAIII) o ;1 ~ ci4--.--~-.--~-r--r--r~r-~--.--.-~--- G,r, 5.C IG.C 15,n 2D.0 ;:5. !I 1(),0 lS.C 10.C 0,0 5,0 HLlJ 1'5.0 :0.0 2S.n :lj n 3'5.0 o Rote(9pm/sqft)~'i.C Role(gpm/sqrtJ~s.o Equollon of Llna: _~l Equot,o~ ~f Ll~e' ~l Y = mX '" b f ~ mX + b m ~O, '~06 m =0.P.d7 j l> -0.0 b 0.2 15 '" J r = 0.91 A 8c: r G.9S <::l l(; 1 c~ c,;; ",l B,-: "'''' w3~ ~ 3iil <..:> D A ',) :.no A '" A ~~ A ~~ w A w :::J :-~ A ..Jo " A ~C', A t~ A " ,,-" A w A w- AA or AA SAND-GARNET .n 'h AA ALL SAND o+--r--r--r~--~-r-'~'--T--r-~----T-~~r--'" ci+--r--r--r~r--r~--.-----.--r--r--r--r--r~~ C.l) 50.0 JO.O 15.0 20,0 ~5,1J 40 r. ~.O 5.0 11'),0 15.0 40-"', :S.O 10 J INFLUENT sownu: !JOO 1m91 L1 INfLUENT :fiLUOLE ocr (mg/ll Figure 15. Relationships between influent and effluent soluble BODs concentrations for each filter type at a 2 hydraulic loading rate of 203.7 21m2-min (5 gpm/ft ). J C' iJ ?l ~ol.lgpm/sqftl;5.0 cl;5.G -.J 0 EquoL l.t)'i of Li..nc~ Li..ne: '.,..m", Y = mX + b E m ;0.175 =D. ,37 §~ b 0.1 ~<-, b I. 5 c.:J~ ; 0.79 ~~ W r O.lD f-cc :::l, 5~ §::!~ o.j· !:..::~ <- g§ O~ ta: ILO <-0 0...... ,~ DC z a z- w a w :3 o ./"" a :.> "-,," a ....J a Wilt a t: "., 0 ~ COAL-SAND COAL-SAND-GARNET W~l ~ 00-0 c "o+--'--.--r--'--r--r--r-.--,-~--,--'--.--r--.-~ C.O S,Q lO.n 15.{) 20.Q 25,Q :m.1J 1S Q ;0, Q a,r; S. a lo,n 15.0 :0.0 :5.0 10.C :r5.O ;0 Q INfLUENT PARTICULRTE BOr, Img/L INfLUENT PARTICULATE gar Img/ll N N '" ?i RoLelgpm/sqflJ=S.O 1=5.0 Equolcc~ ~f Lena: ~ C' 'j Y = mX + b ~~ E m =0.358 C Dc> b 1. 2 b -0.::: CJ~ B" W r 0.66 r ; 0.70 <- <- , 0:: ~ ~'l ....J ::JC' ~~ a <- c >-~ ~l 0::"" "" Figure 16. Relationships between influent and effluent particulate BODs concentrations for each filter type at a hydraulic loading rate of 203.7 X,jm 2 ·m;n (5 gpm/ft2). J " ~~L~I~p~/sqfLJ.~,G ~~i~!~~~/~~ftJ=3.r j' fquaL~~~ ~r L~~9: ~ :~ ::::::. -""I E~u~llcn or L~~~: 'r.: ~ " Y • mX + b ~;~ Y • mX + L rn ::;;r. "':l~r: =~.S~~ lJ -i, r; sJ :::,C' ~ -3,5 ~ :-~ ~ ~ • 0,0= j~ ~ fJ ~:4 " co ~Cl z;r t: C' w -z" e:... t- - • 'n ::J OJ ") L '1 ~ .....z 6 !-.C' • w £3- ::::l • ~ • -' -' to> • • ",,-C' w:.ri • w~ • • • • • COAL -SAND-GARNET • • COAL-SAND a c:i ~_,-----, 6+--'--'--r--r--r--r--.-'--'--'--~-'--.--r--r-, G.a s.!) JO.O 15.0 20.0 25.1') 30.a '15.0 1G.C 0.0 S.C; IC.G 15.0 :t:C.G 2S.!l 30.0 15,0 iO,O INFLUENT SU~PENCEG SDLlrs Img/l! INFLUENT SlJSPENCr.C SGLl C5 I m'-jl LJ N W o ~ ~ R~lelgpm/sqfL)=S.G Kolelgpm/sqfLI.5,D ,C> Equ~lccn of Lcr.e: ~ Eqw~lLor c r' L~ne: 'J1~~ ,'"O'V' E rJ Y = mX + b EN Y • mX + b ·O,i55 m .0,49[ "1 " ;20 b -" I Co b • -:<,'1 ~f3 -, r 0, ?'J ~R I r ::;; O.3~ BJ ~ j ~'" ~~ 'OJ §~]) L' / ..... 0 • §~ 1 6 - J • 3 1 • . /-"/. . c...~~ C' j / • • . /- . SAND-I3ARNET w ~ I • •• •• ALL SAND ':j'~G,O:~~~~~~~--~~~,-,-~--~ 5.S !G.'J J5.1') ~G.G ZS.S 11';.r. :'3.0 ~r: J G.G "s !e r:'. !S," zr. I) :-:-; ".: f.r: -S.r" 1!: r: INFLUENT ::>uJF:NCE'[, ~rjL-][):' ''''g/L J INF"L-UENT ~U~Fr.Nr'[r JL 1',,' "'3/l! Figure 17. Relationships between influent and effluent suspended solids concentrations for each filter type at a hydraulic loading rate of 203.7 ~/m2·min (5 gpm/ft2). J .-.:: ~'le[~~./uqrLJ=S.~ r."L,,! =5.0 Equwl~on or L~r~' " Y=.X·b • =G.4J! rr. ::;c. ~)2S c· b - 1. S do b -1.7 -.0 ~ ~~ r = G,:);': ;) 6 (I <" = 0.35 v> ~ :::i t!: :r: o.J c$ :> ". ~52 ~~ w W -.J :::> ~ -' L... L... L...o ~=- w ....,.: ..... ,:;,."" COAL -SAND-GARNET COAL-SAND "c:i - I 1---' '"o+-~~~--r-'-~--~~--~-'--'.-~--,--- __ -r-----r--' !j,G S.W 10,0 !').:J 20.0 ~'),rj 1Q,C 1') 'J 1C r f' r:J 5.n !fJ,t; It).O ~C r;, ::5.'J ~r,.(. ":i.~ it r: INFLl£NT VOLATlLf. SCi..le:, iF'll!.) INFLUENT VGLhIIL[ 5CL!rS '-~!l N c *'" "~ ~ Rcle(com!soflJ=5.0 Role'~pm/sqrcJ 0 ~" £quol~on of L~ne: b 'o,~ y • tr.X b E .D.H3 If) ., -]. e b -0.8 -00'": 0""" -,,,, r = :3~ C) o.ge a 0.95 0) 'f' W w -'''' -''' f--~'" ;.:::: .:c a: 5 ..J >" ~ .....z -.0 'Z= w w :::> -' -' -' L... u.. L...e> L..." W.,; ./ W·'" •• ~ ALL SAND ~/ SAND-GARNET " '" 0,0 5.D !O.Ci ~"i 'J: ;:0,1) ::5.0 ·'G.a "'S.S ;O.S ~. ~ s.a ~G.1j :5,1) :0 Ij ~') ':: 1':. 0 .,t,_~ ~C 0 INFLLiENT VGLRTlLf:)OLln. :"'g/ll INFLUENT VOLhT!Lf. Sf,LIe.' '''''lh Figure 18. Relationships between i uent and effluent volatile suspended solids concentrations for each filter type at a hydra ic loading rate of 203.7 ~/m2·min (5 gpm/ft2). Table 5. Results of statistical ana1yse3 testing difference between mean influent and effluent concentrations for each quality parameter and hydraulic loading rate. - -, .. ,. =o:.-I!.. Tabu1 ar 81.5 J1./m2·min Q./m2 ·mi n Qual ity 203.7 Student i s~t*** - Confidence Parameter INF Percent Studen~s INF EFF Percent Studen~s Level (mg/ R,) Removed t* Removed t** t t 95% 99% Total BODs 25.9 17.4 33 4.246 23.1 15.3 34 3.817 1.645 2.326 Soluble BODs 10.7 8.7 18 1.644 10.5 9.7 8 0.606 1.645 2.326 Particulate BODs 15.3 8.7 43 \5.8U3 12.6 5.6 55 7.206 1.645 2.326 Suspended Solids 19.1 4.6 76 14.65 17.4 5.0 71 11.89 1.645 2.326 Vo latH e Solids 10.4 3.0 71 8.152 9.2 3.0 67 7.024 1.645 2.326 * degrees of freedom = 58 INF = average influent 0.0246 gpm/ ft2 ** degrees of freedom '" 88 rFr = average effluent *** degrees of freedom = 58 must also be considered [APHA, 1975]. It is difficult BODs and SS removals, the flow rate did affect the period of time a filter performed. Increasing the to demonstrate soluble carbonaceous removal by granular 2 filtration using the BODs test. hydraulic loading rate from 81.5 R,/m 'min (2 gpm/ ft2) to 203.7 ~/m2'min (5 gpm/ft2) decreased the The percent removals of each parameter for both period of filter run by 50 percent. ~ledia depth flow rates were basically the same, except for soluble and configuration also affected the accumulation of BODs and particulate BODs. The influent and effluent head10ss and consequently the period of filter run. soluble BODs concentrations were small and a small The smaller the media effective size, the greater change in concentration results in a noticeable change the headloss development. Figures 20-25 show the in removal efficiency. development of headloss with time for four filters. The difference between particulate BODs removals The coal layered filters provide a longer for the two flow rates is curious because of the solids filter run because the larger pore space allows removal efficiencies. Solids removal was comparable for in - depth filtration to occur. Sand filters for both loading rates, yet the corresponding removals become clogged at the media surface and are of particulate BODs were greater at the higher loading primarily surface straining devices. Surface rate than the lower. Figure 19 shows the relationship straining results in rapid head10ss development between PBOO s concentration and SS concentration for and short filter runs. The longest filter run for both filter influent and effluent and combined flow the sand filter was 9 hours. The maximum run time rates. Particulate BODs concentration was directly for both the sand and coal filters occurred at related to suspended solids concentration. If solids the 81.5 ~/m2'min (2 gpm/ft2) flow rate. were effectively removed by filtration, then the particulate BODs was removed proportionately. Head10ss development in the coal-sand filter (Figures 23 and 24) increased at a greater rate Each of the four filters evaluated was effective than headloss development in the coal-sand-garnet in removing total and particulate BODs, and suspended filter. Typically, head10ss would not terminate solids from the influent stream. Total BODs removal the filtration process as rapidly in the coal-sand was related to the particulate BODs removal. Bio filter as in the coa1-sand-garnet, because the chemical oxygen demand and SS removals were not coal-sand-garnet has a greater overall depth and affected by the hydraulic loading rates studied. clean bed headloss. The increased headloss observed in the coal-sand filter was probably attributable to Headloss Development insufficient backwashing of the filter media. The Although hydraulic loading rate did not affect 25 a o n Effluent. Lt-ne: o Y = mX + b a m =0.673 !J") o N b = 3.6 r = 0.62 o o LEGEND 0= InfLuent. o b. = Ef fLuent. b. b. o Influent. L t-ne: .' o Y = mX + b b. ./ o m =0.803 a u1 ~ b -0.8 b. b. o b. o r = 0.79 0 b. 0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 SUSPENDED SOLIDS (mg/Ll Figure 19. Relationship between particulate BODs and suspended solids concentrations for both filter influent and effl uent. Rote (L/mLn.sq.m)= 81.5 SECONDARY EffLUENT SS (mg/Ll =16.0 (1)0 L • Q)N .,..) Q) e It) (fl • (fl- O o..J a: :::c.Wo - LEGEND o ==cooL-sond-gornet It) o ==cooL-sond d b. == sond-gornet lIE =oLL-sond o m--e~e-~~~ d~-'--'--'--.--'--.-~--.-~--.--.--.--r--r--.-'r-.--,r-.--,--,--.--.--, 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 fILTER RUN LENGTH (hrs.) Figure 20. Headloss development curves for all filters using secondary wastewater as filter influent at a hydraulic loading rate of 81.5 2/m 2 'min (2 gpm/ft2). 26 Rate (L/mLn.sq.m)=203.7 SECONDARY EffLUENT SS (mg/Ll =17.0 U') N (1)0 L • Q)N .,.J Q) E U') (1') • (1')- a o..J a:: Wo :3:...; LEGEND o =caaL-sand-garnet U') o =coaL-sand c:i A = sand-garnet • =aLL-sand o c:i4-~--r--r~~~-.--.--r--~~-.--.--r--r--r-.--.-~--r--r~r-'-~~ 0.0 2.0 4.0 6.0 B.O 10.0 12.0 14.0 16.0 IB.O 20.0 22.0 24.0 fILTER RUN LENGTH (hrs.) Figure 21. Headloss development curves for all filters using secondary wastewater as filter influent at a hydraulic loading rate of 203.7 t/m2'min (5 gpm/ft2). Role (L/mLn.sq.ml= 81.5 TRICKLING fILTER EffLUENT SS (mg/Ll=16.0 (1)0 L • Q)N .,.J Q) E U') (1') • (1')- a o..J a:: Wo :3:...; LEGEND o =coaL-sand-garnet U') o =coaL-sand c:i A =sand-garnel • =aLL-sand o .!.,..EI-B-e-ti:r""' c:i+--.--.--r--~.--.--~~--~~~--.-~--r-~-.r-.--.--r--r-.r-'--'--' 0.0 2.0 4.0 6.0 B.O 10.0 12.0 14.0 16.0 IB.O 20.0 22.0 24.0 fILTER RUN LENGTH {hrs.l Figure 22. Headloss development curves for all filters using trickling filter effluent as filter influent at a hydraulic loading rate of 81.5 t/m2'min (2 gpm/ft2). 27 Rate (L/mLn.sq.m)=203.7 TRICKLING FILTER EFFLUENT 55 (mg/Ll=17.0 III N (1)0 mNL . ....> m E III U1 • U1 .... C) -1 o a: Wo :I:....; LEGEND a =coaL-sand-garnet III [] =coaL-sand c::i t:. = sand-garnet lIE =aLL-sand o c::i+-~--.-~--~~--~-r--~-r--r--r--r-.-~--.--'--'-~--.--.--~-.--~~ 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 FILTER RUN LENGTH (hrs.l Figure 23. Headloss development curves for all filters using trickling filter effluent as filter influent at a hydraulic loading rate of 203.7 ~/m2'min (5 gpm/ft2). Rate (L/mLn.sq.ml= B1.S PRIMARY EFFLUENT 55 (m III =29. 0 III N (1)0 mNL . ....> m E III U1 • U1 .... C) -1 o a: Wo :I:....; LEGEND a =coaL-sand-garnet III [] =coaL-sand c::i t:. =sand-garnet lIE =aLL-sand o c::i+-~--.--.--.--.--.--.--~-r--r--r--r--r--r-.-~r-.--'--'--.--.-~--.--' 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 FILTER RUN LENGTH (hrs.l Figure 24. Headloss development curves for all filters using primary effluent as filter influent at a hydraulic loading rate of 81.5 ~/m2'min (2 gpm/ft2). 28 Role (L/mLn.sq.m)=203.7 PRIMARY EffLUENT 55 (mg/U =23. 0 In I'll (110L . (I) I'll +> (I) e In (f) • (f)- o ....J Cla: Wo :J: • - LEGEND o =coaL-sand-garnel [J =coaL-sand In d tJ. = sand-garnel lIE =aLL-sand 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 fILTER RUN LENGTH (hrs.J Figure 25. Headloss development curves for all filters using primary effluent as filter influent at a hydraulic loading rate of 203.7 ~/m2'min (5 gpm/ft2). underdrain could have also contributed to the head 15 to 20 cm (6 to 8 in) below the overflow level loss increase because of partial clogging of the to prevent loss of filter media during the air outlet pores in the plastic nozzle. scour [EPA, 1974a]. There were fewer operational problems associated with the sand media than with A curious situation occurred at the higher the coal media during backwash. loading rate as shown on the headloss curves in Figures 21,23, and. 25. When the water depth above During the air-scour backwash procedure. some the media reached 1.2 m (4 ft) (same level as the movement of the gravel support layer was observed. filter influent inlet), the inlet hose to the filters This movement, caused by the concurrent air and would fill and cause the distribution box to overflow. water backwash, could cause clogging of the nozzle This reduced the flow to the filters by approximately underdrain with fine sand or coal. 25 percent, and the decrease in slopes of the headloss curves reflect this decline in flow rate (Figures 21, Biological growth within and on the media 23, and 25). The flow reduction did not occur when surface occurred because there was no chlorine operating at the low loading rate. residual in the filter influent. Biological growth and slime on the media inhibited effective back The dual and mixed media filters with anthracite washing. To prevent a slime build-up in the media, coal as the top media layer operated as in-depth backwashing was accomplished using a chlorine filters. Depth filtration provides longer and thus solution >30 mg/~ of sodium hypochlorite (ch10rox). more economical filter runs. With chlorinated backwash, filter operation and backwash were effectively managed. When filtering secondary effluent. daily The sand-garnet and all sand filters were more backwash was necessary, not only because of accumu effectively cleaned by the air-scour backwash than lated head1oss, but for breaking up solids which the coal media filters. The higher specific gravity would compact around the media, forming clumps and of the sand permitted a more turbulent action with mudbal1s. Frequent backwash prevented such solids the air-scour without loss of media. The lighter compaction and mudba11 formation. The sand filters coal media was carried out of the filter with the did not exhibit this problem because the air- ' backwash water during turbulent backwashing. This scour backwash was very effective in cleaning the problem was eliminated by lowering the water level sand media. 29 Filter Cycle Performance from the following steady-state, mass balance: The concentration of suspended solids in the Total BODs = Solub'le BODs + Particulate BODs (1) filter influent varied throughout the day and during the length of filter run. Grab samples of both filter At the filter effluent, Equation 1 can be expressed influent and effluent were taken at different times symbolically as follows: during the filter run and analyzed for suspended solids concentration. The grab samples were taken +P (2) while filtering secondary wastewater in addition to e the composite samples and analyzed separately. The where Te , Be, and Pe are the total, soluble, and SS concentrations are presented in Figure 16 for the particulate BODs concentrations (mg/i) in the common influent, coal-sand-garnet effluent, and all effluent stream, respectively. sand effluent. The variation in effluent SS concen trations does not appear to affect the effluent By using filter removal efficiencies, the concentration for a constant hydraulic loading rate. effluent concentrations can be related to the Effluent quality increased with filter run as more influent: solids are stored within the filter bed. The effluent solids concentration may increase upon filter break T (1 - Et)T (1 - + (1 - E )p (3) through. Studies indicate, however, that pressure e p drops of as much as 9.1 m (30 ft) of water could be where attained in filtration of trickling filter and T influent total BODs (mg/i), activated sludge effluents through dual media filters without solids breakthrough [Baumann, 1977]. The B infl uent soluble BODs (mg/t), effluent SS concentrations from both filters (Figure P influent particulate BODs (mg/i), 26) were the same during the cycle. total BODs removal efficiency, Et BODs Equation soluble BODs removal efficiency, and E particulate BODs removal efficiency. A simple mathematical expression relating the p filter effluent and influent total BODs can be derived o U'1 N C) ~ 0 ->N ""-m E Influent ....J a (f) o LEGEND oWCl . A =FILTER INFLUENT z8 o W =COAL-SAND-GARNET a... lIE =ALL-SAND (f) Effluent :::J (f) o t.0 C) ci~---.----.----r---.----.----'----'---.---~----~---'----r----r---'----'----' 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 FILTER RUN LENGTH (hrs.l Figure 26. Variation of filter influent and effluent suspended solids concentrations during a filter run. 30 Using the relationship shown in Equation 1 for Use of BODs Equation particulate BODs and dividing by T yields the total BODs removal expressed in terms of E , E , and influent Figure 27 is a plot of SBOO s versus TBOO s in soluble BODs fraction (f = SIT). p s the filter influent. The SBOO s fraction, fs, is s readily calculated from the relationship shown in E = -(E - E )f + E (4) Figure 27. The average fraction of SBOOs in the or t P ssp influent stream was 44 percent. The PBOO s removal T = T - (1 - f )E T - f E T (5) efficiency, Ep ' is shown in Table 8 in Appendix A. e s p s s The average value for Ep from 30 combined values Using Equation 4 or 5, the effluent TBOO s was found to be 50 percent with a standard deviation concentration can be calculated if the filter removal of 20 percent. efficiencies are known for soluble and particulate BODs. The equations could also be used to describe A graphical presentation of Equation 7 is BODs removal through other treatment processes. shown ln Figure 28. Effluent TBOOs is determined by locating the known influent TBOO s concentration Assuming that E and Es are constant for a on the horizontal axis, moving vertically until particular filter op~ration, Equation 4 becomes a intersecting the appropriate percent SBOO s line, linear relationship that can be used to calculate the and then reading the value for effluent TBOO s from effluent quality. The slope of Equation 4 is always the vertical axis. negative for the condition Ep > Es. Since granular filters are primarily solids removing devices, E The BODs equation was used to calculate will always be greater than Es' Therefore, the ¥BOO s effluent TBOO s for the filters studied at the removal efficiency will decrease as the influent SBOO s Preston Treatment Plant. Figure 29 shows the fraction, fs, increases. relationships between the calculated value using the BODs equation and the actual BODs determined By further assumi ng that the SBOO s removed (Es) from the experimental study. The slopes in is equal to zero, the BODs equation is reduced to: Figure 29 do not differ statistically (99 percent confi dence). E = -Epfs + Ep (6) or t Lbwda et al. [1978] conducted a filtration T = T[l - (1 - f )E ] (7) study using trickling filter effluent and dual e s p media, SVG pilot-scale filter (Envirotech Corp.). From this expression, effluent BODs is shown to be The BODs equation (Equation 7) was tested using dependent on the amount of PBOO s in the filter the BODs data from this study. The PBOO s removal influent and the ability of the filter to remove efficiency, E , was calculated from Dawda's data PBOO s. to be 69 perc~nt. The calculated filter effluent o ,...,o 0 EqualL.on of LL.ne: ~tri -.IN y = mX + b ...... m E m =0.436 o 0 . b = 0.0 o~ ~ 0) r = 0.88 ~ W -1 0)0 ~ :::::>tri -1- 0 <.n ~ ~zo We ~ :::::>- -1 lL.. ~ Z ~ 0 tri o e~--.---r--.---r--'---'---r--'r--.---r--'---.---.--'---.---r--'---.---r--'---r--I 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 INFLUENT TOTAL BOD (mg/Ll Figure 27. The relationship between soluble BODs and total BODs of the filter influent. 31 o Lf)o~------~ o Lf).... o 00 1Dc:i ..-J '" a: o ~en ON ~ o ~ . z~ W :Jo ..-J . u...~ u... Wo Percent Soluble BODs c:i o c:i~~~--~~~~~~~~~~~~~~~-r~~~~~ 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 INfLUENT TOTAL BOO (m9/ll Figure 28. Graphical solution of Equation 7 to be used to predict filter effluent BODs as a function of influent total BODs and percent soluble BODs. o o .... Aclual Llne: Y = mX + b " 0 m =0.627 .-J o b = 0.9 '-.. . rno E'" r = 0.91 0 0Den IDN LEGEND 0= Aclual oala lIE =Model ~o Z . w~ :J t"lodel Llne: ..-J u...o u... . Y = mX + b w::! m =0.718 b = 0.0 r = 0.99 o o ~--r--'---'--'---r--'---'--'---r--'---'--'---r--'---'--'---r--'---r--'---r--. 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 INfLUENT TOTAL BOD (mg/ll Figure 29. Relationship between filter influent and effluent BODs concentration from data collected and from calculated effluent BODs concentrations using the BODs equation. 32 TBOO s concentration and BOOs data from Dawda's study relationships between the calculated value using are listed in Table 6. Equation 7 and the actual BODs determined from Dawda's study. The BODs equation was .used to calculate filter effluent TBOD s knowing the filter effectiveness in Comparing actual TBOD s data with calculated removing PBOD s by filtration. There was no statis TBOD s concentrations using Equation 7 demonstrated tical difference (95 percent confidence) between the that total BODs was removed in the form of parti actual and calculated effluent TBOD s concentrations. culate BODs. Total BOOs removal is dependent upon The average calculated and actual effluent TBODs the percent of PBOD s in the filter influent and the concentrations were equal. Figure 30 shows the filter efficiency in removing PBOO s . Table 6. Calculated effluent TBOD s concentration using the BODs equation and TBOD s• SBOD s• and PBOD s concentrations from the filtration study conducted by Dawda et aZ. [1978]. Filter Performance Oa ta Filter Influent Concentration Fi Her Effl uent Concentration BODs (mg/ t) (mg/ t) Equation Effluent TBOO s SBOD s PBOO s TBOD s SBOD s PBOD s TBODs 17 8 9 12 8 4 11 13 5 8 8 5 3 7 16 5 11 9 5 4 8 20 7 13 10 6 4 11 19 6 13 9 6 3 10 23 6 17 10 6 4 11 Average Concentrations: 18 6.2 11.8 9.7 6 3.7 9.7 z o >-I LEGEND \--1 0 a:: . 0= Aclual Dolo Q:::lf> \--1- * =Madel Z W U a oZ u~ * o D O en Model Li-ne: Y = mX + b o m =0.390 u-i \--I b = 2.8 Z W r = 0.87 :=J ...Jo L- L- 0 .-t----.----,----._---.---,----~--_r----._--._--_,----._--_,----,_--, W 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.!:J INfLUENT TOTAL BOD CONCENTRATION (mg/ll Figure 30. Relationship between filter influent and effluent from data collected by Dawda et aZ. [1978] and from calculated effluent BOOs concentrations using the BODs equation. 33 FILTER DESIGN CRITERIA SURVEY In order for officials of governmental agencies to Media Type, Size, and Depth assure that wastewater treatment plants produce quality effluents, design standards and criteria are adopted The majority of the desian standards for and imposed. Design standards for wastewater filters wastewater filters permit the following media are also used to assure that the filter will function types and configurations: (1) sand; (2) anthracite; properly in producing a quality effluent. (3) sand and anthracite; and (4) sand, anthracite, and garnet or ilmenite. The effective size for Some of the criteria for design and operation of anthracite, sand, and garnet ranged from 0.8-2.0, wastewater filters which are dictated by standards 0.3-0.8, and 0.2-0.6 mm, respectively. The common are: (1) type of filter apparatus employed; (2) media depths for each layer in a multi-media filter were type, size, and depth; (3) filtration rate; (4) method 38 cm (15 in) of coal, 30 cm (12 in) of sand, and and length of backwash; (5) sampling techniques; and 8 cm (3 in) of garnet. For a dual media filter the (6) underdrain system. A survey was conducted to top coal layer was usually 46 cm (18 in) with a compare wastewater filter standards from each state bottom sand layer of 30 cm (12 in). When single agency in the United States. Each state was asked to media was used, a minimum of 50 cm (20 in) of sand send a copy of their standards dealing with wastewater was imposed. filtration. Thirty-seven states responded to the request for information, and of this total 30 percent Backwash did not have design standards for wastewater filters. Of the 37 states that replied, 14 states have adopted All wastewater filter design standards called the "Recommended Standards for Sewage Works" (10 State for backwash appurtenances complete with air scour Standards) . or mechanical scour. One standard required 50 percent bed expansion during backwash while 12 Types of Filters standards required 20 percent expansion of each media layer. The other state standards specified 110st state standards allow the installation of minimum backwash rate that would assure adequate either gravity flow filters or pressure filters. One bed expansion during backwash. Backwash water flow state only allowed the use of gravity flow filters. rates ranged from 610.0 £/m2·min (15 gpm/ft2) to A choice between upflow and downflow filters was also 1222.2 £/m2·min (30 gpm/ft2). The most common common. backwash flow rate was 815.0 £/m2·min (20 gpm/ft2) with 10 minutes of backwash time. Backwash storage Rate of Filtration was also required with sufficient volume for two successive filter backwashes. Allowable filtration rates for wastewater filters ranged from 81.5 £/m2·min (2 gpm/ft2) to 488.9 £/m2·min Summary (12 gpm/ft2) depending upon the type and depth of fil ter media employed. The most common rate for a Table 7 is a list of all the states that single, dual, or multi-media filters was 203.7 £/m2·min responded to the survey. Hydraulic loading rate, (5 gpm/ft2). The majority of state agencies base the depth and size of media, and backwash methods and allowable hydraulic loading rate on the type and confi procedures are each addressed in all of the design guration of media employed. One state allowed hydraulic standards for wastewater filters. For complete loading rates of 122.2 £/m 2·min (3 gpm/ft2) for single details of the adopted standards for the design of media, 163.0 £/m 2·min (4 gpm/ft2) for dual media, and wastewater filters, the particular state agency 203.7 £/m 2·min (5 gpm/ft2) for multi-media filter should be contacted. configurations. 35 Table 7. Summary chart listing those states that responded to the filtration survey and the name of document containing wastewater filtration standards. State Name of Document or Standard Employed Comments Al aska none Arizona Minimum Requirements for Design, Submission of Rate: 81.5-488.9 t/m2 'min Plans, and Specifications of Sewage Works California Wastewater Reclamatiqn Criteria Co lorado Filtration Standards Rate: 122.2-326 t/m2 'min Media depth: 30-122 cm Delaware none Florida none Design for 90 % BOD and TSS removal Georgia Rapid Sand Filtration Design Criteria and Sand effective size: 0.45-0.55 mm Requirements Hawai i none Follow Public Health Regulations Idaho Criteria for Sewage Works Design Use only as guidelines 10 State Standards Illinois 10 State Standards Rate: <203.7 t/mZ'min Backwash rate: >815 t/m2 'min Indiana 10 State Standards Iowa 10 State Standards Kansas none Kentucky none Louisiana 10 State Standards lla ine 10 State Standards Use only as guidelines 11aryland Filtration Process Rate: 81.5-203.7 t/m2 'min l-1ichigan 10 State Standards Minnesota 10 State Standards r·1ississippi EPA Suspended Solids Removal Manual Mi ssouri 10 State Standards Montana none New Jersey Rules & Regulations for the Preparation and Rate: 122.2 t/m2 'min Submission of Plans for Sewer Systems and Sand depth: >50 cm Wastewater Treatment Plants New Mexico 10 State Standards Use as guidelines New York 10 State Standards Ohio 10 State Standards Oklahoma Standards for Design of Water Pollution Control Facil ities Pennsylvania A Guide for the Preparation of Applications, Rate: 203.7 t/m2 'min Reports, and Plans. 10 State Standards Tennessee Design Criteria for Tertiary Sand Filters Rate: 40.7-163 t/m2 ,min Texas Design Criteria for Sewage Systems Rate: 122.2-203.7 t/m2 'min Utah Proposed Filtration Standards Draft only Vermont none Virginia Virginia Sewerage Regulations Rate: 122.2 t/m2 'min Washington Criteria for Sewage Works Design Rate: 122.2-244.4 t/m2 'min West Virginia Filtration Regulations Draft only Wisconsin 10 State Standards Wyoming 10 State Standards 36 SUMMARY) CONCLUSIONS) SIGNIFICANCE) AND RECOMMENDATIONS Summary and Conclusions removing BODs and solids by filtration. Because of more stringent water quality standards 3. Filter performance was generally independent for wastewater treatment plant effluents, it is of the two hydraulic loading rates employed frequently necessary to utilize advanced treatment [81.5 and 203.7 i/m2 ·min (2 and 5 gpm/ft2)J. processes to improve the overall performance of However, filter operation and length of filter wastewater treatment plants. Tertiary filtration of run were affected by hydraulic loading rate. wastewater secondary effluent is one such treatment Increasin~ the loading rate from 81.5 i/m2 ·min process. (2 gpm/ft ) to 203.7 i/mz'min (5 gpm/ft2) reduced the length of filter run by 50 percent. Removal of suspended solids and biochemical oxygen demand from secondary effluent of trickling 4. All filters were effective in removing total filter operations is critical in order to meet and particulate BODs. and suspended solids. present and future discharge requirements. The Granular media filtration of wastewater was results of this experimental study will be helpful not effective in removing soluble BODs. in determining if tertiary filtration of wastewater Soluble BODs removal may have been more will upgrade existing processes sufficiently to significant at lower loading rates but was satisfy quality standards. difficult to determine using the BODs test. Four filter columns were operated at the waste 5. Dual and mixed-media filters with a top coal water treatment plant located in Preston, Idaho, to layer provided longer, more economical filter examine the effectiveness of granular media, gravity runs. The coal media allows in-depth filtra filtration to remove BODs. soluble BODs, and suspended tion, whereas the sand media filters were solids. The Preston plant produces a secondary surface straining devices. effluent utilizing a trickling filter for the biologi cal treatment process. Anthracite coal, silica sand, 6. Suspended solids removals increased during i, and garnet sand were the granular materials used as the fi 1ter run. filter media. Four different filter bed configura tions and depths were studied. Mixed media, dua1- 7. The sand media was effectively backwashed by media, and single-media beds were constructed with air-scour without loss of media. The lighter the following media configurations: (1) coa1-sand coal media was lost to the overflow during garnet, (2) coal-sand, (3) sand-garnet, and (4) all turbulent, air-scour backwash. sand. 8. The mathematical BODs equation describes The filters were operated at two hydraulic filter performance in terms of TBOD s removal 2 Z loading rates: 81.5 i/m ·min (2 gpm/ft ) and 203.7 and demonstrated the dependence between i/mz·min (5 gpm/ft2). Wastewater effluents from the influent and effluent quality. The equation plant's primary clarifier, trickling filter, and was effective in calculating effluent TBOD s secondary clarifier were filtered to determine the concentration using BODs data from the filters difference in performance when filtering different studied at Preston and the filter tested by effluents. Dawda et al. [1978J. The BODs equation demonstrated TBOD s removal was dependent upon Wastewater quality parameters used to monitor the PBOD s removal efficiency of the filter. filter performance were biochemical oxygen demand (total, soluble, and particulate BODs), suspended solids, and volatile suspended solids. 9. Implementation of secondary wastewater filtration at the Preston Treatment Plant could A mathematical equation was developed to produce an effluent of 10 mg/i suspended calculate the filter performance in removing total solids, but could not satisfy a 10 mg/i BODs BODs· The equation was evaluated with data collected requirement. from the experimental study at Preston and from a filtration study conducted by Dawda et al. [1978J. Engineering Significance The following conclusions are based on an analysis Wastewater filtration with granular media is of data collected from the four types of filters not a reliable treatment process for removing operated at the Preston Treatment Plant. soluble biochemical oxygen demand (SBODs). Granular filtration is effective in removing suspended 1. Filter effluent quality is dependent on the sol ids (SS) from wastewater. I~astewater fil tration influent quality for removal of BODs and will reduce total BODs (TBODs) concentrations in suspended solids from wastewater by granular accordance with the solids reduction and the amount filtration. of TBODs associated with the solid material. If a wastewater treatment plant produces an effluent 2. The coa1-sand-garnet, coal-sand, sand-garnet, containing a TBOD s concentration with a low and all sand filters all performed the same in percentage of soluble BODs. wastewater filtration 37 will further reduce the TBODs by removing particulate Recommendations BODs related to the solids. If a high percentage of the effluent TBODs is attributed to soluble BODs, the 1. Conduct a filtration study to compare the filter will not be effective in removing TBOD s. performance of wastewater filters when filter ing chlorinated influent versus unchlorinated In regard to present and future wastewater influent. discharge requirements, wastewater filtration can produce an effluent which will meet a 10 mg/£ or even 2. Determine the minimum chlorine dosage in the 5 mg/£ SS concentration. However, the capability of backwash water required to effectively inhibit the secondary treatment process to reduce soluble biological growth and slime accumulation on BODs must be carefully evaluated in order to impose the media when filtering unchlorinated influent. or expect an effluent TBODs concentration of 10 mg/£ or less upon implementation of granular media 3. Determine the effect of filter influent filtration. chlorine concentrations on filter performance when filtering a chlorinated influent. Because the coal-sand-garnet, coal-sand, sand garnet, and all sand filters were equally effective 4. Examine the possibility of filtering primary in removing BODs and SS from wastewater, the type of wastewater effluent for further treatment or media should be chosen from economic comparisons. direct discharge. The additional garnet layer in the multi-media and dual media filter beds did not improve the filtrate 5. Study the possibility of significant soluble quality but created larger clean bed headloss and biochemical oxygen demand removal by waste shorter filter runs. The dual, coal-sand, filter water filtration when operating at filtration bed produced the longest runs and equivalent filtrate rates less than 81.5 £/m 2 'min (2 gpm/ft2). quality. 38 LITERATURE CITED American Public Health Association. 1975. Standard rves, K. J., and I. Sholji. 1965. Research on MethodE of Examination of Water and Wastewater. Variables Affecting Filtration. J. San. Eng. 14th Ed. New York. 1232 p. Div., ASCE 9l(SA4}:1-18. Baumann, E. R. 1977. I~astewater Filtration Design Matsumoto, M. R., T. M. Galeziewski, and G. Considerations. Proaeedings of the Utah Water Tchobanoglous. 1980. Pulsed Bed Filtration PoUution Control Assoaiation Annual Meeting. of Primary Effluent. Presentation at the April 21-22, 1977. 129 p. 53rd Annual Water Pollution Control Federa tion Conference. September 30, 1980. Baumann, E. R., and J. Y. C. Huang. 1974. Granular Filters for Tertiary Wastewater Treatment. t1etcalf & Eddy. 1979. Wastewater Engineering J. Water Poll. Cont. Fed. 46(8):1958-1973. Treatment Disposal Reuse. 2nd Edition. McGraw-Hill Book Co. 920 p. Cleasby, J. L., E. W. Stangl, and G. A. Rice. 1975. Developments in Backwashing Granular Filters. r.1i ddl eton, F. M., and R. L. Stenburg. 1972. J. Env. Eng. Div., Amer. Soa. Civil Engr. Research Needs for Advanced Waste Treatment. 101 (E E5) : 71 3-727. J. San. Eng. Div., ASCE 98(SA3}:515-528. Cleasby, J. L. 1969. Filter Rate Control Without O't-1elia, C. R. 1980. Aquasols: The Behavior of Rate Controllers. J. AWWA 61(4):181-185. Small Particles in Aquatic Systems. Environ mental Saienae & Teahnology 14(9):1052-1060. Cowan, P. A., D. B. Porcella, V. D. Adams, and L. A. Gardner. 1978. Water Quality Analysis Proae O't1elia, C. R., and W. Stumm. 1967. Theory of dures syllabus. Utah State University. Utah Water Filtration. J. AWWA 59:1392-1410. Water Research Laboratory. 95 p. Ott, L. 1977. An Introduation to Statistiaal Culp, G. L., and R. L. Culp. 1974. New Conaepts in MethodE and Data Analysis. Wadsworth Water Purifiaation. Van Nostrand Reinhold Co. Publishing Company, Inc., Belmont, CA. 730 p. 305 p. Steel, R. G. D., and J. H. Torrie. 1960. Prinai Dawda, M. M., ,.1. L. Davidson, and E. J. mddlebrooks. ples and Proaedures of Statistias. r~cGraw 1978. Granular r·1edia Filtration of Secondary Hill Book Co. 481 p. Effluent. J. Water Poll. Cont. Fed. 59(9):2143- 2156. Tchobanog1ous, G. 1970. Filtration Techniques in Tertiary Treatment. J. Water Poll. Cont. Environmental Protection Agency. 1974a. Wastewater Fed. 42:604-623. Filtration-Design Considerations. Technology Transfer. EPA-625/4-74-007a. 48 p. Tchobanog1ous, G., and R. Eliassen. 1970. Filtration of Treated Sewage Effluent. J. Environmental Protection Agency. 1974b. Proaess San. Eng. Div., ASCE 96(SA2):243-265. Design Manual for Upgrading Existing Wastewater Treatment Plants. Washington, DC. October. Tebbutt, T. H. Y. 1971. An Investigation into 340 p. Tertiary Treatment by Rapid Filtration. Water Researah 5(3):81-92. Environmental Protection Agency. 1975. Proaess Design Manual for Suspended SolidE Removal. Van Dyke, D. 1980. Performance of Granular Media Washington, DC. EPA-625/1-75-003a. 250 p. Filters for Tertiary Treatment of Municipal Secondary Biological Effluents. Proaeedings Environmental Protection Agency. 1980. Evaluation of the Utah Water Pollution Control Assoaiation of Full-Saale Tertiary Wastewater Filters. Annual Meeting. April 17-18, 1980. 87 p. Cincinnati, Ohio. EPA-600/2-80-005. 194 p. Walters, J. G. 1979. Designing for Coarse Sand Hsiung, A. K. 1980. Chlorine Effect on Secondary Filtration Systems. Water & Sewage Works Effluent Filtration. J. San Eng. Div., ASCE 11 :44-45. 106(EE3):649-654. Weber, W. J. 1972. Physiaoahemiaal Proaesses for Irwin, J., and G. Garzonetti. 1980. Wastewater Water Quality Control. John Wiley & Sons, Filtration: New Innovations, Applications, and Inc. 640 p. Cost Savings Technique. Proaeedings of the Utah Water Pollution Control Assoaiation Annual Yao, K. M., M. T. Habbian, and C. R. O'Melia. 1971. Meeting. April 17-18, 1980. 89 p. Water and Wastewater Filtration: Concepts and Applications. Environmental. Saienae & Teahnology 5(11):1105-1112. 39 APPENDICES APPENDIX A Filter performance data from pilot-scale study conducted at the Preston Wastewater Treatment Plant. 41 .J Table 8. Influent and effluent total BODs data from all filters for Table 9. Influent and effluent soluble BODs data from all filters both loading rates tested. for both loading rates tested. TOTf'l1. )301) ))ATA L,OADING SOLUBLE BO)) DATA LO(~IHIW RATE Rf:'fF:. DATE INFLUENT FlI..TE~: EFFLlJf:.NT (MG/l) (GPMI r!AT[ XI~FLUENT F:(I.TEI~ EFFUJF.IH (MG/L> ( OPI11 (MG/L) "".FT.) (MG/L) S(l.FT,) 1 ~~ 3 4 1 ~! ~ 'I :;'-i'-BO 16. 10. 1 j • 11. 11. 5.0 ::J-l'-(l(l 6. '/. 8. 6. B. !~(0 ~' 0-1 '1 '. loW 17. 1 :~ , 1 tj. 14. 1 tl • ~.o 5- i 7··00 5. .... !5 • 1. 4. ~.O !.5-:·!2·~80 9. 0. ~~ . 12. B. 5.() 5-~!~"-1!0 6. 0'.... II. 6 • t). 5.0 6-i'J'-IW 22. i!:l. j t .• 16. 15. 5.0 6-19'·110 11. :il, 1 ~~ • 10. j,0. 5.0 6-20-'00 17. 5,0 H. a. 7. 7. 6-2(l-H(l 5. ~.... !.I. 5. :.5. ~tO 6-;! i'-B(l 23. :to. Il • 7. 7. ~5(O 6-n '-BO 7. 6. 5. Il • '\ . 5.0 /.-2:)-'BO 16. S' • 11. 10. 8. 5,(1 6-2!i-'B(l 5. 6. 6. .... ~'J • 5.0 /.-26··11<1 ", " 19. 1... 12. 10. to. 5,0 6-26"B(! 10. S' • 10. 10. 10. ~~.O t.-2'1··B(I 15. 10. 10. 7. o. 5(0 t,-:n-uo 8. i .• 6. '1 • 'I. 5(0 1,-:..lB'·H(1 30. 20. 20. 1 'i'. ~!O • ~i.O 6-2H'-8(l 19. 15. j :3 • 16. lB. ~~.o 7-;!"HO 31. ~~1 • 21, 20. 19. 5.0 l-~!'-B(! 18. 1 s. :l6. 14. 1 ~t. 5.0 7-:~"U(l 33. 23. 23. ;~o • 22. 5.0 7-~~"HO 14. 1~. 1 4 • 12. 14, 3.0 '1-;~"U(1 53. ~~1 , :~::-: 38. :~6 • 5.0 ;-;7,'-U(! 24. ~!4 t ~~j , 25. ~~~! • ~5toO +> . N 7-4-'110 29. :?:I , -22. 19. 19, ~.() 7-r,··U(l 16. 14, 1:r. ~ 12. 12. 5.0 7-16"80 31. ~!O 0 =~o • :~2 . 2(1. 5.0 7-16'-Il(l 12. 1;::. i~' • 13. 1~! • 5.0 8-'1"110 14. 11. 11. 12. ~2. 5.0 B-7U(l 7. 6. 6. 8. B. ~5.0 o· 8-8-00 19. 14. :I .... 13. :l~! , 5.0 B-·u·-no 8. 8. 8 • 7. 6. 5.0 1:1-1 :~'-O(l 22. 19. 16. 17. 19. ~.O 8- L~" BO 8. 10. "I. 10. 9. 5.0 7-17'·nO 31. 20. ~!O 0 18. 18. 2.0 7-n'-no 12. 11. :11. 9. 10. 2.0 'J-1B"UO 36. 21. 22c 22. ,;::,.",c' 2.0 l"18 .. B(· 14. 14, 11. 14. 15. 2.0 '1-1')'-1l 12. 'i'. 9. 12. :li. 2.0 13-2"UO S. 7. 7. 6. 6. ~! c () flVEIH~B~: 24.2 16.:1. il>. :;, 15.9 :16.1 f.lVEr~(10f:': 10.6 S·. (, ') .1{ 9.0 9.2 51}) nEV. 'i'.5 6.B 6.4 6.5 b.8 ~:nl DEV. 4.7 4.6 4.4 4.8 ~."1 PERCENT IU:MOVAL :~2.. It :~2. I> 34.3 :~~~.6 ~'ER(;F.I-IT j(~~110VAL s· • ~5 Ud) 14.8 J;,!.9 1 COAL-RAWB-DARNEl eO(.II.'-BMW-GARNEl 2 COAL"RAND ;! CO~II.-H{!IHI 3 SAND-UARNET 3 HMW-GM::NET 4 ALL BAND 4 (~u. Bf-lNJ) CONV[IW XON: (;:PH/HU. FT. 40.1~ LPM/HQ. METER eONV~:I~!):CONl 1 Gf'M/B(l,FT < 4(\. 'l~ I. l-'illHtl • METER J Table 10. Influent and effluent particulate BODs data from all Table ll. Influent and effluent suspended solids data from all filters for each loading rate tested. filters for each loading rate tested. PARTICUL~TE BUD DATA LOADING SUSf'I~!mF.n HOI.Xl)!) ItATA LO{tllXNO R~TE RM[ D(tH HIFLUENT fILTER EfFLUENT (MG/l) (UPMI DATE XNFlUENT FILTER EFFLUENT (MG/L) (lWllI ( MG/L> DU.fT. ) (MG/L> t't/.FT.) 1 2 3 4 1 ~~ 3 4 t'i- l ··flO 10. 3. 3. 5. 3. !)c 0 5-1"80 10. 1 • ~~ . 3. O. ~). 0 !)-17"BO 12. B. 9. 10. 11.., ~:... 0 5-17"UO 15. 6. 6. 7. 5. :) .0 5-2~!"1I(1 3. 3. 4. 6. ..." !'i. () 5-2~!··1}(1 11 • 1. 2. 2. 2. !hO 6-l')'-ll. 4. 5. ~! .() 0-1'-00 13. 12. 12. 12. 1l. 2. () H-l"IIO 16. 4. 4. :S. 3. ;.~ c (l t: -:! .. UO 4. ....'I 2. 6. !) • 2,() B-~!"IIO 13. 2 • ~~ . 3. 3. ;·!.O AVERADE 13.7 6.6 6.9 6.9 6.9 AVfR~OE 18.1 1:.7 5.1 1i.7 1:./ STn DEV. 5.8 :5.1 3.:l ~ .1 :~. 7 RTD DEV. 5.7 :~ • 1 3. (, 2.8 :1,.0 PERCENT REMOVAL ~12. (l -19 • :r, 19.3 "I ').!'i PERCENT REMOVAL 74.0 71.(' 74.2 74.0 1 COAL"SAND-GARNET 1 COAL-SAND-GARNET 2 COAL-SAND 2 CUAL~BAND 3 HAND-GARNET 3 HAHD-DARNET 4 ~LL RANU 4 ALL HANn CONVERBIllN: 1 OPK/Hll. I: T. 4(1.74 LPM/DO. METER CONVERRXON~ 1 arM/Ull.Fl. 4(1.74 LrM/BO. METER Table 12. Influent and effluent volatile suspended solids data from all filters for each loading rate tested. VOLATILE Hnum, nATA l.(j(~IH 1-16 R(.ITI:. XNFLUENl' fILTER EFFLUENT (MOIL) WPMI (MG/L) tit!, F'j , ) 2 3 '1 :.:i-:i.·-UO c';;;. 1. :J. 1. 3. ~) • 0 5-1/'-B(l 6. 3. 3. 1, :~ . 5« (~ c' 5-:' :.~._!l(l .:I. o • j • O. 1 • ~=j. 0 6- j ';--BO 9. 1 • 1. 2. :~ . ~). 0 {,-20"BO 9. ~~ 2 .. !:i.O .,. 1. . 3. {,-:?:t .. HO .. . ~! • 1 • 1. 2. !:; ( (i 6-2:5-8(' 9. 4. :~ . ;~ . ?o. !){ 0 4-2f>'-SO 5. O. (t. O. O. !5.0 6-·2/··8(1 5. 1. ~~ . 1. 1. ~;j. 0 6-:~H'-B(l 1. 1. O. 1. i • ~), 0 7-2·-B(l 8. 2. 2. 2. ? • ~). 0 /-:r,··U() 19. f. U. 7. O. ~:.; «. 0 /.':!"'!l(! 22. 10.., 11. 9. (i. :5.0 /-4"1l(l 14. .' . f>. 6. b • ~:} + 0 '/-1 (,··gO 17. B. 7. 6. f>. ~\. (I 8-/"UO 6. 3. ;.~ . 1. ~! • ~~;. 0 B··l-J··!l() 1(). :!i. 3. 3. >1. !:;.o fJ- 1 :~'-B(l 8. ;} . :~ . 2. 2. !5.0 7-i /··80 18. f. /. 5. 6. ~! (0 7-:tB'-IHl 17. 6. 6. 7. ~'t • ~!-{ 0 7"l')"!Hl 15. 6. 6. 7. ;: . 2.0 '1"2:~'-B(l 11. 1. -, 3. >1. ;,,0 '1-24·-BO B. 1. ""1. 1. 1. :l.O ,.. 7<~~)"80 • J. O • O. 1. I) , 2.0 l-;U"'IW 7. ".... :l. 1. 2. :,'.0 /-~~B"B(1 12. ~ . ~i • 4. 3. :;~ , 0 c· /-;W-B(' ;;;. 1. O. o. :~ . 2.0 7-3i"UO 13. 5. 4. II. -I. :·!.o 8-i"U(1 S. 3. 2. 2. 1. :~. 0 S-:?"BO 6. 1. :I.. 2. ~:~ . ~!. 0 AVUU,llE 9.7 3.(1 :~. :t 2.8 :~. 1 5TH nEV. 5.0 2. () 2. ~, 2.5 ...... " ..,..:.. F'ERGEIH 1~f:J10VAL 69.0 6/,7 ')1.1 (,11.0 COf.ll. ... S(il~n-6ARNE·1 ~! C()(.IL"·BM~n 3 B~)NJ)"'HMNt:::T 4 (.11..1. HIlHD (;ONVEI·; ~l(()I~: 1 al-'M/!W,F'(, .. 4(1.'14 lPN/SQ. Mr.lER 44 APPENDIX B Filter performance data from pilot-scale filtration study conducted at the Preston Wastewater Treatment Plant. Tables 12-26 are tabulated results from filtering pri mary, secondary, and trickling filter ef fluents. 45 Table 13. Influent and effluent total BODs data Table 16. Influent and effluent suspended solids filtering primary effluent for each filter data filtering primary effluent for type and loading .rate. each filter type and loading rate. SUSPENDED SOLIDS DATA :"OAt'ltW FILTE!=: FFF! !)EWf (jiti/L) (' GF't1.' F:Af£ DATE rl'lFL~f.j'l r (rH,/; '> 5(1. f ., • i DATE INFLUfH' FILTE~ EFFLUENT (MG/LI (GF'MI SQ.FT. ) 3 4 7-3-80 32. 12. 13. I:! • 7-Il:-SO 8. :>.0 36. :;:::'. e. 19. 7-J6-S0 9. 10. s.o B. :',8. 2; • 7··1 ~:-3t) ,s. :t-:23-E;'') 22. 5 • 3. 4. 7-23-90 3~~. A!)ERAGE 24.9 i?9 8.1 2.9 2 .8 24.4 ST.!) [lEV. 4.3 2.7 "EReENT REMOVAL 67.2 7 ,t·,.3 .9 32.7 COAl-SAND-G~R~ET 1 COAL-SAND-GARNET : COAL-SAND 2 COAl-!:\AND 3 '3ANII-CAF:t!ET SANli-GARNET 4 ALL SAND 4 AU_ :3MHf SONVERSION: 1 GPM!SQ~~r. 40.74 LPM/SQ, METER CO:':'j:,RSION: GrM/~Q.~r. :- 40.74 L~H/SO~ HFT~R Table 17. Influent and effluent volatile suspended Table 14. Influent and effluent soluble BODs data solids filtering primary effluent for filtering primary effluent for each filter each filter type and loading rate. type and loading rate. VOLATILE SDI.JlIt:.: h;;rh t or~l!:uw f<11 i E SOLUE,l £ i-;:Ol! [it'ITA !NFllW!'~ 1 FIL.TEF: E::-FLU€NT «(>18: !.) (GPM/ ("GIL. :' SCLj.."f. :' DATE FIL TEF: EFTL !}Ei'H (HI3/1 I. Gf'rt/ 2 S(LFld 3 -::-80 10. 11 • '? • 9. -.4~80 tiJ, 5. 6.' 6. , 7-3-80 24. 5.0 -!e.-so :.1:.: , S. 7. 6. 6. 7-4-80 16 I 13. P 12. -17-80 113, 7. 5, c.. ,"-,'-'16-80 12. 13. -18-80 17 " 6. 7. 7-17-80 1"', ! 1 • 11- -1';<-8"0 15. { . 7. 4. ':,'-18-80 14. H. :1. 14 • 2.0 -23-80 11. 1, 3. 3. 4. 7-19-80 1.7. lB. 16. 7-23-80 13, 14. 14 • 12. AVERA8E 16., 6.1 /" 6 5. ST'O lIE\). ,:l",J 2.8 2.4 I , A'iERAilE l~'. PERCENT REHOVAL 6~.3 5?6 62.3 64 ~ STD [lEl,!, 4.2 f'ERCENT F:EMO'JM~ COAL-SAHli-GARNET 1 COAL-SAND-GARHET " COAL-SAND 3 SANO-GI~Ri.JET ;;: COAL-SAND ALL SAN V SANt'-GARNET 4 ALL SAH1) CO~H)ERSlON; [O~VERSION: 1 GPM/SI1,F!. ~ 40,74 LPM/SG. MET~R· Table 15. Influent and effluent particulate BODs data filtering primary effluent for each filter type and loading rate. P~RTICULhTE BOD PATA LO:~IIING R{:TE DATE: ] i·'F~ tJl: NT F!LTEt:.: U .. FLtIENT (/'iu/Lj UlPM / (~~G/L: SG.f'1'. ) :-3-80 13. 14. ~'j. 0 7-4-80 7. :,,0 7-1t.-S(' 8. 9. 8. .0 :?-17-S<:' ~. 9. 9. 8. .0 7-113-80 7. I!. B. 10. 2.0 7-19-80 12. 1 " 10. 12. 2.0 7-23-BO 9. 11. 11. 13. :,.0 A1.JERABE :':0. '7' 9.1. 9.6 J 0.3 srt, {lEV. ;:".J :,"'. :, ,0 2.8 PERCEHT F:EMO')"L 56.2 50.7 1 COAl-SA~D-GARNET COriL-SA!HI :3 ~:;MHt-GARNET 4 ~l.L SAND 46 -~. Table 18. Influent and effluent total BODs data Table 20. Influent and effluent particulate BODs filtering trickling filter effluent for data filtering trickling filter effluent each filter type and loading rate. for each filter type and loading rate. DATE 1;"fLUU~1 PILlE? ~FFLU~Mr (hG!~: (1,;1£ ,"FLUEllT F Il TER EF- Fl UEIl! UW/L} (Gf'h/ .\ nG/L ~ .f T d (MGlL) SttlFT 4} -::0-8.0 l:~ j 3. 3. 6-20-8~ 1:', 8. 8, 7. ~" 0 -21-80 1,:;:.. 4. 3. 3. 5.0 6-:::1-80 :3. 1'} • 8. 7 • 5.0 -~::·-80 1 t 5. c-25-80 161 11. 10. a. S,O 3. o. 6-,26-80 19. 12. 10. 10. -27-80 I. 6-27-80 15. l(), 10. 7. ~;. 0 -.2':::-80 11. 5. 3. 0-2$-80 30. :0. 20. 19. :0. <-so 1,', " , s. ,-s.. 7-1-80 31. 21. 21. ZJ) • -3-,~O 1~'. s. /-;!,-8C· 33. -:'1 -so 1 I 4. 7. 7-24-80 19. 11. -25-80 14. 10. 6. 10. 7-25-80 2::'. l' • 15. -2t-8l"l l:'t 7. 7. t. 7-26-80 28. -'28-30 is'. 8. ':3. 0, 7-28-80 ;::'? AI)::r::AGE 13.2 5.5 S. j .\, B AVEF:AGE 23.8 14.1 El[1 DE!,I, 3.7 .~ 'r c.8 3.1 STn IIEV~ ,:';.4 5.3 5.1 ~EF:U:·.I'!T REHCIt,lt\L e,l .4 63. PERCENT REMO'}{';L 41 •.1 40.:'1 CDAL-SA~D-GARNET 1 COAL-lAND-GANNET .2 CD~L -SA!'!£: 2 COAL -SArtI) 3 SAND-GAHN!:7T '3 SAND-GARNET 4 ALL SAND ALL ::1i'HHl CONVERSID~: 1 GPh'SU.FT. Table 21. Influent and effluent suspended solids Table 19. Influent and effluent soluble BODs data data filtering trickling filter effluent filtering trickling filter effluent for for each filter type and loading rate. each filter type and loading rate. LG,:,(,ll"l& SOLUBLE Brr~ D~I~ LO,',)I(N(; t':':I') E RATE ~N~~_I"!r.~i FIL'tr~: r,FF:"U[:"li (I'1G,'!..:' I, GI.'M,! IiA!'E INFVJEl'n Sll.FT ... {t'lG/L 1 sn. FT J ) 3 6-20-30 U:. 3. 5.0 6-20-80 5. s. b-21-30 13r 5.0 ';-2!'~80 5. .. 6-::!::-SO lB. 6. 5. S. :5.0 6-:!S-t{O 6. 6. 5. ..'l-25.-80 1. 1. .0 6-~6-80 9. 10. 10. 10. 6-27-80 1L 6-27~BO 8, o. 4. 4. 6-::8-80 12. ::.. 6-2B-8'~ 15~ 1.6. 7-2-80 17 • 4. .'~2-e" 16. 14 ~ 7-2-80 11. 10. j 0, 7-2-80 14. 14 • 121 7-~4-f:O 15, 3. ,(\ 7-24-80 5. 4. 7-25-80 14, ~ . 3. ,0 7-25-S0 11 , 7. 6. .0 7-26-80 1::. 2. o 7-26-80 LL 6. 7. 6. 8. 7-28-80 24. ~. 6. 6. .0 7-28-90 1. O. 8. a. AVERAGE 1 ~.1 3.6 :;,8 .3 3.6 10.<1 8.6 7.9 8.6 STII DEV. ~;Il :.7 :.4 .1 4.7 4.2 4.2 4.8 f-'ERCENT ~:£MOl)AL 77,1 .3 .:'7.7 REMtJV~IL :(1-1.9 25.2 l8,'? COAL-SA:~D-GAkNET COAL-BAND-GARNET :J COAL-S;;tHI 2 COAL-~~A~~D SI~ND-ij,':-.RI'l ~T SAND-GAF:NE'T AU SAtHr 4 ALL S~';Hj CONVERSION: Gf'M/SQ, r r • 40.74 LPM/SG. METfR 47 -~. Table 22. Influent and effluent volatile suspended Table 24. Influent and effluent soluble BODs data sol ids data filteri ng trickl ing filter filtering secondary wastewater for each effluent for each filter type and loading rate. filter type and loading rate. LJ.; It 1;,;( l)'jt ,!;TJU. Lttl,'tI: I N::? SOLUBtr POD D~T~ ~::=l T £ f.:'~ rE (I,;.;H1/ ihiTE r~:~LrJf·N.7 'G:'"-M/ SCL FT d ()1G/l) .:;or]. F'r ) 5~1-glj 6. ~;. 0 1 • s. B. ! • 5-17-80 5. 4. ~! • 0 6. :; 4. ::; . 3. ~" 0 . ,';-1,-80 11 • 11. 11. ! O. 10. 6-26-80 5, O. o. O. ~', , I) S-;'-80 6. 8. S. :-27-PO 5. 1. 1. 1. 5.0 8--8-80 l:i, "8. . ;'-:;8-80 .\. 1. 0, 1. 1. 8. ~-2-E:"O S. 5.0 8-1:3-80 lC' • 9. --3-8C' 19" 8. 8. ]--30-80 6. 4. ~ . 4. "-24-30 s~ 1 • 1. ~.o ~-31-80 " '7. 8-1-20 .;::., --'--:'25-80 5 ~ o. o. 2.0 s. 8. R-~-£O S. 6. :-26-80 J. 2. ~.O 3. 4. 2.0 AVERAGE 7.:- 7.2 1'.7 6.7 tlVEF..!"f3E e. ,;':' 2.0 2.2 1 • 'I STD [lEV. 1. 1.9 STD [lEI). ~.:: 2.0 • 1 PERCENT I<"MOV(,L 9.8 ~'EF:C£N1 f-;E:~O;"'HL 75.0 76.(: .9 CD~L-SAND-GARNET CO~L-SA~D-3ARNEl COAl-'~:A~'[l COAL ~·S(d'~!) SHNn~'8:;F;NET :"Ill. ~J~·'jHD 3?({D~GH!i:HET ~ ;;:""l 3ANfi COMVEFSIONI 1 GPh/SQ •• ,. ~0.74 LPH!SO. METER Table 23. Influent and effluent total BODs data Table 25. Influent and effluent particulate BODs filtering secondary wastewater for each data filtering secondary wastewater for filter type and loading rate. each filter type and loading rate. , O(,J) Ur:; l.DADJ 1·:0 F:;'lT F:A 1 E INFl Utr:" FILrE~ ~FFlUENr 5-1-'81) 10. l. J, 3. '3.0 5-1-8~· H. 11. 1.1, ~-17-80 1'2, 10. :,-17~80 J. , 14. 5-22-80 4. 3. 5·~2.:::.'- 30 r;.' 8. 12. 8. 6-1'~-80 11 • 4. 4. ':.-19-80 £:-7-80 5. s. 8-7-80 1 l • 11. B-3-:30 7. 1 S. 13. 8- L"·-80 10. 17. • 'J 7-3G-80 H. 6. .,,.,.! 4. '11 • 1: • 11. .0 ::-:;ld -80 13. 11 • 11. 1" 1:. 7-31-80 18. if:. j S. 18. • 0 €~-:r-P.O 13 • 12. 12~ 12. 11 ~ 8-{-80 2:: • B. • 0 8-~:··80 4 . 2. 6. S. b-2-2C' 11 • .0 AIJERAB£ 9. ,,, .3 7.0 AIJEF:AGE j. J LL5 1400 D.7 STI) ilE,V. ::>.7 3.3 ST[I DEV. 4 1 ::; 2.8 3.7 PERCf.HT REI-lOIH1L 34.9 PERCt:H r f:t:rW'JAl 1. '1.7 COAL -SP1Nfl-(i{.P.NET 1 COAL-SAND-G~HNfT COAL-SIlM[I ::: (OA!_-SAt~!:1 Z S,'lI·/D·--GfU,H£T 4 :";LL Sr,;~D CDNVERSIONI 1 B~"/SC.~T. CDNVERSION: ~ GPM/SU F7 4C.7~ LP~!S[:. HETER 48 Table 26. Influent and effluent suspended solids data Table 27. Influent and effluent volatile suspended filtering secondary wastewater for each sol ids data fil teri.ng secondary waste filter type and loading rate. water for each filter type and loading rate. LfiArl tNt: f:ATE IjOL.AI.li E 20L!rl~ (lATA L -J t1 [; [ ~.' ':. flAl E .r !"!Ft ill- j-!l F!.LTEF: EFFI tlr-J·n ( GF'M/ h'(, I E. ~HG:L) ~,Q.I- ! • ) 2 [lAT~. ] NFLur::~:1 F IL TfF: ~ f. F 1.IJEi'!"1 (r1(",/L " (t~r·M .. (.HG/l) 5-1-Er) 10. I 3 3 O. ~, 0 ~-1 7-80 lj, b. 7 5 t.:. 0 " 5-1-f:1) 5. .,:, ~-:2-S0 11 1 2. " 2 .,. 0 1 2 1 3 .-,-: 5-1/-80 t· • 3. -, 1 0) /J-:!.9-80 :; 6 • o. 6 .' 'J -' ., ~-22-8') o • 0 1 O. 1 8-7-80 1 0 4 4. 4 .' .) c' 6-1-:.'-80 1 1 0 8-8-80 17 5 4 4 > .. ' 0 ., o. 8-l-80 6 3 1 :.~ C· £:-!:~-80 1 ~ 5. ~-; O. ~I • 0 C;--8-80 10 "-30-80 3• o. 3 ! • -::: . 4 0 15. 3 c· 2 Ie. .; f.:-13-80 8 ~ ;) ?-:!"!.-80 ,0 ::. 6 4 5. 2. 0 '. 3 7-30-80 5 1 O. o. 8-:-80 !t < 4 3 3. ]. 0 a 7'-31-90 l:': 5 4 4. (; 8-:-8C.. LL :2. -, 3. 2. 0 8-1-80 £: :. 2 0 "1 " t;-2-80 ~ ; ~ .. 1 1 ~. 0 AI.IEi=:AGE 1 ., 9 .0 4 3.9 3.• 6 STD DEI). 3 8 7 1 ~ -1 , 4 1 ? . AI.,.IERAGE 7 4 1 .0 1 .6 PEF:CENT F:EMOVAL 73 • , 75. 4 77 1 2 5 STll [lEV. - 5 5 ~ ! ." 1 0 f·EF:CF.NT .h:ENC!J",~L 4 ::3 c· COAL-SAND-8A~~ET '17 ·:-.6 7 COAL -SAN!.t 1 COAL-SAND-iiARNET 3 SAN[1-\3AKf'!E::T : COAL-S~tJn • ALL S~tJIt SAND-GARNET , riLL :; :~I ;.! [, COt,Il.'ERSION: 1 GF'M/SG.!=T. ~'. ,:i).?~ I..~·M/SO. H!::TER CONVFRSIO~: 1 GPM/SQ.~ 1, 49