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Application of horizontal series filtration in greywater treatment: a semi-industrial study

Mehdi Bahrami , Mohammad Javad Amiri & Morteza Badkubi

To cite this article: Mehdi Bahrami , Mohammad Javad Amiri & Morteza Badkubi (2020) Application of horizontal series filtration in greywater treatment: a semi-industrial study, Australasian Journal of Water Resources, 24:2, 236-247, DOI: 10.1080/13241583.2020.1824610 To link to this article: https://doi.org/10.1080/13241583.2020.1824610

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Full Terms & Conditions of access and use can be found at https://engineersaustralia.tandfonline.com/action/journalInformation?journalCode=twar20 AUSTRALASIAN JOURNAL OF WATER RESOURCES 2020, VOL. 24, NO. 2, 236–247 https://doi.org/10.1080/13241583.2020.1824610

ARTICLE Application of horizontal series filtration in greywater treatment: a semi-industrial study Mehdi Bahrami , Mohammad Javad Amiri and Morteza Badkubi

Department of Water Engineering, Faculty of Agriculture, Fasa University, Fasa, Iran

ABSTRACT ARTICLE HISTORY One of the important alternative water sources for non-potable purposes is greywater, but Received 19 June 2019 needs to remove contaminants. The aim of this study was to investigate the performance of Accepted 14 September 2020 a horizontal series filter (HSF) consists of sand, zeolite (Z), pumice (P), and granular activated KEYWORDS carbon (GAC) to analyse the chemical oxygen demand (COD), biochemical oxygen demand Greywater; zeolite; Granular (BOD5), total dissolved solids (TDS), turbidity, and pH in greywater samples from Fasa University Activated Carbon; pumice Student Hostel, Iran. Recycling treatment was performed by passing the greywater through filters. After the last filter, treated greywater was returned into the main tank. The system was run at filtration rate of 2.94 m3 day−1. The analysis of the data from the filtration tests showed that GAC is the best adsorbent for removing COD, BOD5, and TDS from greywater, followed by zeolite. Whereas, pumice is more advisable to remove turbidity. However, due to the different mass of adsorbents in the filters, pumice showed a higher adsorption capacity than zeolite. Generally, the triple combination of GAC+Z + P represented the best performance in the reduction of COD, BOD5, TDS, turbidity up to 90.42%, 91.43%, 82.95%, and 90.27%, respectively. Therefore, the studied system can be implemented in public places to greywater treatment and reuse.

1. Introduction water sources, such as rainwater tanks and greywater systems that supplement mains supply (Coombes and In many major cities across the world, the availability Mitchell 2006; Troy 2006; Australian Bureau of of water for urban around homes, parks and Statistics 2017; Coombes, Barry, and Smit 2018; sporting areas and for peri-urban agriculture and hor­ Bureau of Meteorology 2020). Consequently, using ticulture irrigation is becoming critical (Yiasoumi unconventional water resources, including greywater et al. 2008). As the pressure on freshwater resources is inevitable. Up to 60% of fresh water is being used for is growing up around the world due to population landscape, irrigation, toilet flush tank, and other pur­ growth and new resources of freshwater are becoming poses that do not require using fresh water (Venot, more expensive and scarcer, new alternative resources Molle, and Hassan 2007 2016). should be considered to supply the water demand. For There have been a number of researches on aspects example, the extended drought in regions such as Iran of greywater reuse, particularly in Australia, EU, and Australia within the last few years has led to Japan, Israel, and the USA (Friedler 2008). Countries a greater emphasis being placed to develop policies and on-ground actions for conserving and recycling in the arid areas such as Iran, Saudi Arabia, Kuwait, water, and consequently to provide a permanent sup­ Cyprus, and Jordan can potentially reuse greywater for ply of water (Pinto and Maheshwari 2010; Bahrami, non-potable objectives and possibly diminish the pres­ Bazrkar, and Zarei 2019). In recent decades in Iran, sure on their fresh water supplies. In some countries, the successive droughts and mismanagement of water non-treated greywater has been applied for irrigation resources have led to intense water crises, especially in of sod and silviculture. For example, greywater reuse is southern Iran. Excessive extraction of , becoming increasingly common among households in low efficiency of irrigation, disposal of wastewaters in Western Sydney (Pinto and Maheshwari 2010) or is surface water supplies, which can lead to groundwater typically applied in a raw, untreated form, primarily contamination, and inefficient management in virtual for landscape irrigation in Australia (Barker et al. water discussion are examples for mismanagement of 2013) and vegetable gardens . water in Iran. In Australia, major sources of water for Although, this type of usage can be damaging as it urban water utilities are dams, rivers, streams, ground­ may cause soil salinity depending on the soil type water bores, desalination plants, and recycled water (Lucas et al. 2017). Because greywater can be polluted plants. Many customers also have their own on-site with enteric pathogens and may, therefore, pose

CONTACT Mehdi Bahrami [email protected] Supplemental data for this article can be accessed here © Engineers Australia AUSTRALASIAN JOURNAL OF WATER RESOURCES 237 a health risk if the irrigated product is consumed raw. consistent for garden irrigation and toilet flushing in Views about greywater have changed in recent years, Cranbrook. They reported the common greywater with developed countries such as Australia, the USA, treatment mechanisms including constructed wetlands, and Japan leading the way with reuse (Barker et al. modified sand filters, wet composting, amended soil 2013). Today, it is proven that treated greywaters can filter, basic two-stage systems (coarse filtration plus be considered for washing, cleaning, irrigation, indus­ disinfection), biological systems (membrane bioreac­ try, and many other non-potable uses (USEPA. United tors (MBR)), biologically aerated filters (BAF), and States Environmental Protection Agency 2004), and rotating biological contactor (RBC)) are competent for has been already used in many dry regions around the coping with Australian domestic recycling water stan­ world for non-potable water demands (Almeida et al. dards. In Australia, the greywater comprises showers, 2013; Zipf, Pinheiro, and Conegero 2016). In this hand basins, bathroom, and laundry from 100 units in context, greywater reuse is one of the main options an apartment complex was treated for different goals for diminishing potable water consumption in house­ such as of garden beds, subsurface irri­ holds, commercial buildings, and industries (Couto gation of grassed areas, and toilet flushing. In another et al. 2015). Greywater is defined as a huge part of case, the treated greywater was used for drip irrigation municipal wastewater that is not polluted by toilet of trees and landscape areas of a local park. In all wastewater, which called black water. Up to 80% of projects, microbial and chemical hazards in greywater, domestic wastewater can be greywater (Eriksson et al. calculation of microbial health, preventive measures to 2002). manage microbial and chemical risk were considered. For all residential water use, only a little quota serves From 20% – 50 % of Australian households utilise the potable quality purpose, which covers almost 9% of relatively untreated greywater for outdoor use (Troy indoor water use in Western Australia (Loh and 2006; Geary et al. 2006; Shah et al. 2007; Australian Coghlan 2003). The remaining non-potable uses, such Bureau of Statistics 2017; Lucas et al. 2017). In this as toilet flushing, clothes washing, and garden irrigat­ study, we used norms and regulations of USEPA ing, can satisfactorily be supplied with alternative water (2004), Iranian Standards, Australian Standards, and sources (Zhang et al. 2010). Reusing greywater is standards of some other countries active in the field of increasing practice in the area of water research in the greywater treatment for treated greywater reuse (Amiri last decade, especially in countries where regulations et al. 2019) (Table 1). For reaching to these standard encourage this practice and by-laws, such as the USA, limits, using a proper treating system and application of Australia, and Germany (Barker et al. 2013). The inven­ efficient adsorbents can be the main matter of physical tion of a feasible, efficient, small, low cost, and long treatment. lifetime greywater treating system, which can be proper In view of the above, the aim of this study was to for use in dense and crowded cities, is the main priority assess the effectiveness and performance of three effi­ in the treatment industry (Oh et al. 2017). Various cient adsorbents, i.e., granular activated carbon, nat­ technologies are being studied, like coagulation by ion ural zeolite, and pumice in single and combined forms exchange resin (Pidou et al. 2008), flocculation (Chang, for the removal of COD, BOD5, TDS, pH, turbidity, Cornel, and Wagner 2007), moving bed biofilm reactor and turbidity from greywater. For this, a horizontal (Chrispim and Nolasco 2017), trickle media filtration series filtration (HSF) system consists of four filters system (Shamabadi et al. 2015), slow filters of sand and was filled with different materials to treat real grey­ slate waste followed by granular activated carbon (Zipf, water collected from the dormitory of Fasa University, Pinheiro, and Conegero 2016), drawer compacted sand Fasa, Fars Province, Iran. Recycling the greywater in filter(Assayed, Chenoweth, and Pedley 2015), pelletised the system improved the purification capability. Based mine water sludge (Abed, Almuktar, and Scholz 2017), on a thorough search of the relevant literature, there aerobic attached- growth biomass (Song et al. 2017), are no reports about the application of single and wetland (Ramprasad et al. 2017), green walls combined adsorbents in the form of a continuous (Prodanovic et al. 2017), biofilter (Moges et al. 2017), system in greywater treatment. compact hybrid filter systems (Karabelnik et al. 2012), physicochemical treatment (Noutsopoulos et al. 2017), and anaerobic filterfollowed by UV disinfection (Couto 2. Materials and methods et al. 2015). Chemical and biological or chemical and physical combination methods can be used for grey­ The experimental system consisted of a storage tank water treatment to reduce the chemical methods’ costs and a greywater treatment system installed at labora­ (Eslami 2017). Zhang et al. (2010) used onsite greywater tory of the Fasa University in the city of Fasa, Fars treatment technology of membrane bioreactors fol­ Province, Iran. The horizontal series filters used for lowed by ultraviolet disinfection due to the small foot­ treatment was four PVC cylinders with a length of print and high quality of effluent, in Western Australia. 80 cm and a diameter of 15 cm were filledwith desired Treated greywater was believed to be reliable and filters, arranged as follows (Figure 1): 238 M. BAHRAMI ET AL.

b The horizontal series filters used for treatment was and 2.2 - - 0 a

1000 four PVC cylinders with a length of 80 cm and 1000 400 200 100 1000 1000 1000 < < 100 Coliforms a diameter of 15 cm were filled with desired filters, arranged as follows: ------2 2 10 10 (a) Sand containing four layers in filter one (Table Turbidity 2 and Figure 2), arranged from coarse to fine. This filter was produced by Recommended - - pH 6–9 6–9 6–9 6–9 6–9

6–8.5 Standards and Guidance for Performance, 6.5–8.5 6.5–8.5 6.5–8.5 6.5–8.5 Application, Design, and Operation and Maintenance Recirculating Gravel Filter limits - - - - - 1000 450 TDS 1500 2000 Systems by Washington state department of < health (Washington state department of health, c Permitted 2012). 300 (b) Granular activated carbon in filter two, pur­ 5 and 100 30 10 20 10 30 60 15 30 40

b chased from Merck Company, Darmstadt, 240 BOD <

200 Germany (product number 1,025,141,000). To , a

30 avoid the bad effect of this substance dust on the turbidity of treated greywater, the granular

b,c activated carbon washed with distilled water

500 before filling the filter. - - - - - 150 30 50 90 150 150 COD and < (c) The third filter contained zeolite originated a

100 from a mine in Darab, Fars province, Iran. Natural zeolite was washed with distilled water to losing its dust. by (d) The last filter was filled with pumice, prepared Standards Standard Standard Standard Standards

EPA EPA from a mine in Arsenjan, Fars province, Iran. Standards Standards Standards WHO WHO

US US To contain three layers pumice sieved to pass Arabia

Iranian Iranian through 4, 16, and 20-mesh sieves. For clearing Recommended Tunisian Jordanian Jordanian Jordanian Australian Saudi the dust and any other undesirable substances, this filterwas washed with distilled water before

raw using it to treat. irrigation. eaten

in Characterisation and amounts of used adsorbents in

crop filters shown in Table 3.

any These filters and tank were connected together by

and tubes. This study was operated using real greywater, application effluent from men’s bathroom sinks, showers, hand for basins, and the kitchen sink in a student dormitory processed block with 250 residents. Physicochemical and micro­

standards biological analyses of the raw and treated greywater were performed, which allowed the efficiencies of the cities

commercially system to be evaluated and compared. A 100 L tank quality be side be

outside was used for flowregulation prior to the filters,also for not and and

will 24 hours to settle the suspended solids and increasing crops will roads

that dissolved oxygen and was also applied for flow regula­ of uncooked that

fodder tion before the filters. The greywater was sent via side crops treatment forestry playgrounds

eaten crops a pump to the proposed treatment filter at a constant and of 3 −1 food and be areas, flow rate (at 2.94 m day ) controlled by a tap with areas, food to trees and a bypass system diverting excess effluent into the sew­ crops storage and green degree fruit likely age disposal system. After that, the treated greywater parking areas areas areas and and areas

and was returned to the tank by a tube from the final filter. cities parks industrial processed trees

required This cycle continued for 6 hours and treated greywater recharge streams public and irrigation crops ornamental vegetables restricted restricted restricted inside vegetables, irrigation to samples were taken in 15, 30, 120, 180, 240, 300, and crops, of of for of of of for The

1. 360 minutes after the system operation at the end of roads Plenteous Field courses commercially Non-food pastures of b: c: Cooked the operating cylinder. In addition, the breakthrough Restricted Unrestricted Irrigation Irrigation Golf Irrigation Irrigation a: Applying Discharge Groundwater Irrigation Irrigation Table AUSTRALASIAN JOURNAL OF WATER RESOURCES 239

Figure 1. Schematic arrangement of the HSF.

Table 2. Specification of applied sand. COD was measured by spectrophotometer (unico Layer Mesh number Aperture (mm) 2100), BOD5 was measured by a manometric BOD5 First 4 4.750 measuring device (oxitop is 12), and turbidity was mea­ Second 16 10.188 Third 30 0.600 sured by turbidity metre (Lamotte 2020 we). By the way, Fourth 40 0.425 all experiments were performed with three replications. Considering 7 adsorbent compounds, three replications, and sampling at eight times in each experiment, a total of curves of COD were obtained by measuring this vari­ 168 samples were collected. In each sample, 5 parameters able history in the effluent. including COD, BOD5, TDS, turbidity, and pH were For studying the purification power of the different measured. Finally, based on the results of the effluent filter materials, the system was in operation every time water quality, potential applications for treated water with two, three, or all four filters. Meanwhile, the sand filter always was operated on the system and one, two, or three others were added every time. The following variables of water quality were analysed in samples: Table 3. Experimental filters characterisations. biochemical oxygen demand (BOD5), chemical oxy­ Particle Specific surface size Density area (SSA) (m2/ Mass Volume gen demand (COD), total dissolved solids (TDS), tur­ 3 3 Adsorbent (mm) (Kg/m ) g) (Kg) (m ) bidity, and acidity (pH). All parameters were analysed Sand - 1920 0.0444 26.88 0.0141 according to Standard Methods for the Examination Granular 2–2.8 305 1000 4.30 0.0141 of Water and Wastewater ( 2012). The methods Activated Carbon used for the analysis of each variable are displayed in Zeolite 0.8–1 2470 805.9 34.58 0.0141 Table 4. Pumice 10–80 250 100 3.50 0.0141

Figure 2. Schematic order of the applied sand. 240 M. BAHRAMI ET AL.

Table 4. Number of tests and methods of analysing variables. 3.2. Adsorbents Number of Reference no. in Parameter Method analyses standard method The analysis of the form and geometry of the grains of COD Open reflux, 168 5220 C granular activated carbon, zeolite, pumice, and sand titrimetric method via scanning electron microscopy (SEM) are illu­ BOD5 5-day BOD test 42 5210 A pH pH method 56 4500-H+ strated in Figure 3. The high porosity of granular Turbidity Nephelometric 168 - activated carbon and rough surface of zeolite particles TDS Total dissolved solid 56 2520 conductivity are the most important factors to make them suitable Total 490 adsorbents. Likewise, less efficiency of sand and pumice is expected because of their lower porosity level. Anyway, availability and low cost of pumice were identified in consultation with USEPA regulations and sand make them inevitable to use. for non-potable water reuse. The removal efficiency (%E) and the adsorption capa­ −1 city (q) (mg g ) of the HSF treatment system were 3.3. Comparison of different filter materials measured by analysing greywater samples from effluent by means of Equations (1) and (2), respectively The purification ability of different filter materials was (Bahrami, Amiri, and Koochaki 2017). Samples were compared on the basis of the median parameters of collected prior to and after the filters. treated greywater. According to the values of COD removal efficiency given in Table 6 (raw greywater C À C −1 E ¼ 0 � 100 (1) COD was 350 mg L ), should be noticed that the C0 efficiency of sand filter in the reduction of COD was less than 5% after 6 hours. Although the changes in hydrophobicity in sand particles may affect on sand q ¼ C0 À C � V (2) efficiency (Maimon, Gross, and Arye 2017). Actually,

Where C0 and C are indicator concentrations before the sand filter could only protect the system from the and after the filters in the samples (mg L−1), respec­ damages of large particles in greywater. tively. V is the volume of solution (L) and m is the Figure 4 shows the COD reduction in different adsorbent mass (g). combinations of filter materials. As seen, the presence of granular activated carbon in filter promotes the COD reduction ability. Also, according to curves var­ 3. Results and discussion iation, the optimum time for COD removal from grey­ water by every filter is about 4 hours. After this time, 3.1. Raw greywater characteristics the reduction rate of COD is less than 5%. In addition, The raw greywater characteristics expressed in Table 5 the values of COD removal per unit mass of the by the average and standard deviation of the para­ adsorbents (q) (Table S1) indicate the highest GAC meters, while these parameters compared with earlier adsorption capacity, followed by P. reported values by the other researchers (Zipf, Variability of greywater COD with time in form of Pinheiro, and Conegero 2016; Shamabadi et al. 2015; breakthrough curve is obvious in differentcompounds of Chrispim and Nolasco 2017; Sievers et al. 2016). It was filter materials in Figure 5, where C/C0 ratio (C0 is the observed that the turbidity and pH were higher than in raw greywater COD initial concentration and C is COD any of the results of the other studies. The obtained concentration of time taken samples) drawn versus time. values of COD and BOD5 were higher than in other Breakthrough curves demonstrated that the treatment literature except by Sievers et al. (2016). In general, the intensity of filters is very low after 250 minutes so that studied raw greywater in this research was more con­ after this point, the slope of breakthrough curves is centrated than cases studied in the same researches negligible. Likewise, breakthrough curves attest that the relatively. lowest C/C0 rate has occurred when we used all filter

Table 5. Comparison of studied raw greywater parameters with that used in other studies. (Zipf, Pinheiro, and (Shamabadi (Chrispim and (Sievers et al. This study Conegero 2016) et al. 2015) Nolasco 2017) 2016) Bathroom sinks, showers, hand basins, Lavatory sinks in Household Parameter and kitchen sink a university campus Bath/shower Showers greywater COD (mg L−1) 350 ± 22.89 145.8 ± 79.1 291 272.8 746 −1 BOD5 (mg L ) 280 ± 18.56 56.0 ± 15.9 129 123.1 460 TDS (mg L−1) 2800 ± 219.07 - - - - Turbidity (NTU) 185 ± 6 35.8 ± 45.1 55 100 - Faecal coliforms None detected - - - - (NMP/100 mL) pH 8.26 ± 0.3 7.7 ± 0.6 6.3 - - AUSTRALASIAN JOURNAL OF WATER RESOURCES 241

Figure 3. SEM images of granular activated carbon (A), zeolite (B), pumice (C), and sand (D).

Table 6. COD removal efficiency in different filter materials components (%). Generally, results show that the maximum COD Filter Time (min) removal happened when the filter system operated material 15 30 60 120 180 240 300 360 with all of four materials. When dual filter (included GAC 2.94 13.51 31.69 50.37 60.44 66.09 67.81 68.30 sand and another filter among GAC, Z, and P) Z 0.98 6.38 21.13 29.97 50.12 55.53 57.74 58.23 P 0.73 1.96 8.10 10.31 13.02 22.60 23.34 25.55 worked, the best performance was obtained by GAC. GAC+P 4.42 15.47 33.66 51.35 63.14 69.53 72.73 74.20 One of the most important specifications of adsorbent GAC+Z 6.38 19.41 36.36 57.25 68.30 71.99 74.69 75.43 Z + P 1.71 3.68 26.29 34.64 52.82 60.69 64.62 65.60 in physical treatment is porosity and SSA (Albalawneh GAC+Z + P 8.59 26.29 40.78 74.20 83.29 87.22 89.93 90.42 and Chang 2015), that granular activated carbon has For more comfort, first letter of each adsorbent chosen as the abbreviation the most specific surface area (SSA) and porosity for that filter. among other adsorbents. In addition, GAC has a great quantity of permeability (Zipf, Pinheiro, and materials to treat greywater. Pursuant to the curves, the Conegero 2016). These characteristics can be reasons COD reduction rate during the first1-hour was very low. for GAC efficient performance in reducing greywater 242 M. BAHRAMI ET AL.

100 90 80 )

% 70 (

n

o 60 i t c 50 u d e

r 40

D 30 O

C 20 10 0 15 30 60 120 180 240 300 360 Time (min)

GAC Z

100 90

) 80 % ( 70 n o

i 60 t c 50 u d

e 40 r 30 D

O 20 C 10 0 15 30 60 120 180 240 300 360 Time (min)

GAC+P GAC+Z Z+P GAC+Z+P

Figure 4. COD reduction (%) by different compounds of filters materials.

1 0.9 0.8 0.7 0.6 0 C

/ 0.5 C 0.4 0.3 0.2 0.1 0 0 50 100 150 200 250 300 350 400 Time (min)

GAC Z P GAC+P GAC+Z Z+P GAC+Z+P

Figure 5. Breakthrough curves of greywater COD influenced by different compounds of filters materials.

COD. During the operation of filter including three SSA, in comparison with pumice, it indicated lower materials (sand and two other filters), the function of adsorption capacity for COD removal, which can be granular activated carbon + pumice and granular acti­ attributed to the higher mass of zeolite in the cylinder. vated carbon + zeolite was similar. In both of them, Also, the values of BOD5 removal efficiency are granular activated carbon improves the function of represented in Table 7 (BOD5 concentration in raw filter for COD removal. Despite the zeolite higher greywater was 280 mg L−1). After 6 hours and by using AUSTRALASIAN JOURNAL OF WATER RESOURCES 243

Table 7. BOD5 removal efficiency in different filter materials These results also are indicative of the highest capacity components (%). of GAC (396 mg g−1) that leads to the maximum q for −1 Filter Time (min) GAC+P (403 mg g ). material 15 30 60 120 180 240 300 360 Table 9 and Figure 6 show the reduction of turbid­ GAC 2.99 13.56 31.74 50.42 60.49 65.14 67.86 68.35 Z 1.09 6.49 21.24 30.08 51.2 55.64 57.85 58.34 ity by various materials. Using all filters, after 6 hours P 0.69 1.92 9.22 10.27 12.97 22.56 23.29 25.50 caused 90.27% of turbidity reduction. Results show GAC+P 4.36 15.42 33.60 52.29 63.08 71.26 72.67 74.14 that after the triple system, pumice has the best per­ GAC+Z 6.42 19.44 36.40 57.28 68.34 72.02 74.73 75.46 Z + P 1.64 3.60 26.21 34.56 52.75 71.84 64.54 65.52 formance among other filters for turbidity removing. GAC+Z + P 8.61 26.30 42.80 74.21 83.31 87.24 89.94 91.43 So, the compounds containing pumice have more reduction in turbidity compared with others. The results of the adsorption capacity of the filtermaterials all filters,COD and BOD were removed by 90.42%. In 5 for turbidity removal represented in Table S4 indicate terms of BOD reduction, GAC adsorbent shows the 5 that pumice has the highest value of removal per unit highest adsorption capacity and Pumice is next (Table mass of the adsorbent. The structure of pumice is S2). The present horizontal series filters recorded bet­ sponge-like and this structure was perfect for trapping ter results compared to the works of Shamabadi et al. turbidity maker agents. When greywater moved on (2015) and Zipf, Pinheiro, and Conegero (2016) in a pumice stone, the paths of the capillaries in the COD reduction after 4 hours. Choosing an optimum pumice stone were a good place to capture the turbid­ time is necessary to save time, reduce the energy cost, ity agents. and prevent system exhaustion. Figure 7 represents the filtering greywater pH Results of different compounds of adsorbents func­ changes, while raw greywater pH was 8.26. Initial pH tion for TDS reduction are presented in Table 8. The of greywater is effective on adsorption process, optimum time for TDS reduction by all of the com­ because of surface charge impressionability from pounds was about 3 hours. Performance of GAC and initial pH (Bahrami et al. 2012). The standards for GAC+Z + P for TDS reduction was similar, but gen­ the purified wastewater usage have identified the per­ erally, GAC was a favourable adsorbent for this pur­ mitted pH range in the treated wastewater. pose. The results of the adsorption capacity of the filter Approximately all of these standards, including materials for TDS removal are represented in Table S3. USEPA, allow the pH of purified effluent to be

Table 8. TDS removal efficiency in different filter materials Table 9. Turbidity removal efficiency in different filter materials components (%). components (%). Time (min) Filter Time (min) material 15 30 60 120 180 240 300 360 Filter material 15 30 60 120 180 240 300 360 GAC 10.36 24.64 42.86 59.29 71.43 76.08 79.24 82.80 GAC 0.54 2.16 8.11 16.22 37.84 48.65 52.43 54.59 Z 7.50 25.71 41.43 58.21 64.29 65.00 67.62 70.21 Z 1.62 3.24 10.81 22.70 45.95 61.08 67.57 69.73 P 4.29 18.21 34.29 45.71 49.64 51.43 51.58 51.87 P 3.78 7.03 14.05 24.86 55.14 67.03 77.30 79.46 GAC+P 10.71 27.14 45.00 61.43 72.86 75.36 76.02 76.42 GAC+P 4.32 7.57 16.76 27.57 51.35 62.16 70.27 73.51 GAC+Z 6.43 21.07 35.71 49.64 54.29 57.50 59.00 59.62 GAC+Z 2.16 3.78 11.89 23.24 52.43 62.70 75.68 77.84 Z + P 7.14 22.14 37.86 51.79 58.21 62.50 63.48 63.78 Z + P 5.95 8.11 18.38 29.19 59.46 71.89 84.32 85.95 GAC+Z + P 12.14 28.57 47.86 64.29 74.64 80.36 82.15 82.95 GAC+Z + P 8.11 9.73 19.46 35.14 64.86 76.76 88.65 90.27

100.00 90.00

) 80.00 % (

l 70.00 a v

o 60.00 m

e 50.00 r

y

t 40.00 i d i 30.00 b r

u 20.00 T 10.00 0.00 15 30 60 120 180 240 300 360 Time (min)

C Z P C+P C+Z Z+P C+Z+P

Figure 6. Turbidity reducing percent in different filter materials components. 244 M. BAHRAMI ET AL.

10 9 8 7 6 H

p 5 4 3 2 1 GAC Z P GAC+P GAC+Z Z+P GAC+Z+P Filter compounds

pH after 3 hr pH after 6 hr

Figure 7. pH changes in various compounds of filters after 3 and 6 hours. between 6 and 9 (Table 1). The initial pH value of greywater for use in plenteous trees and green areas, greywater is related to fresh water supply and added side of roads outside cities, field crops, industrial substances by humans such as chemical detergents crops, and forestry where the residual COD, BOD5, (Noutsopoulos et al. 2017). When granular activated and TDS in treated greywater were lower than 500, carbon filter is used, the mitigation of pH proves that 200, and 1500 mg L−1, respectively. But based on the the adsorbed mechanism of the adsorbents is cation- Australian Standards, among the single adsorbents, by-cation exchange (Aghakhani, Mousavi, and only the treated greywater using GAC was appropriate Mostafazadeh-Fard 2012). By using a zeolite filter, for applying in golf courses and parks. In Australia, pH increased obviously. The main reason for anion greywater reuse is becoming more common, particu­ adsorption is ion-exchange by zeolite, which influ­ larly in arid cities such as Melbourne (Barker et al. ences pH to be increased (Aghakhani, Mousavi, and 2013). Treated greywater is now commonly used in Mostafazadeh-Fard 2012). These results reveal that Australia for most daily non-potable activities (e.g. applying granular activated carbon, zeolite, and toilet flushing and garden irrigation), and also for pumice together could prevent the intense changes in industrial applications and irrigation purposes the case of pH. (Pham et al. 2011). Overall, among the different combinations of None of the single and double combined adsor­ adsorbents, the triple filter containing GAC+P + Z bents were effective in treating greywaters in exhibited the best performance in greywater treat­ a permissible level of COD for groundwater recharge ment. In general, the main factor in the success of (<50 mg L−1) and reuse for restricted irrigation −1 the HSF system for greywater treatment is GAC fol­ according to Tunisian standards (BOD5 < 30 mg L ) lowed by the zeolite adsorbent, which in most cases (Table 1). Accordingly, the performance of triple com­ showed a higher removal percentage than pumice. bined adsorbents was acceptable, for which the COD However, in terms of removal per unit mass of the residual reached 35 mg L−1 (< 50 mg L−1). The treated adsorbent, pumice operated better than zeolite in greywater by triple combined adsorbents is appropri­ removing COD, BOD5, salinity, and turbidity. The ate for restricted irrigation of landscape according to reason for the differences in the result of the removal the standards of various countries and can be dis­ efficiencies is due to the same duration of time chosen charged into surface water and groundwater (Table for the filters. Because of the difference in the density 1). Therefore, the results indicate that single adsor­ of adsorbents, a different mass of each adsorbent was bents alone are not adequate to guarantee a sufficient placed inside the filters.In fact, comparing the pumice reduction of COD. and zeolite, we can conclude that taking into account In Iran, reclaimed greywater can even be used to the equal mass of both of them, pumice adsorbent is stabilise the soil and prevent from forming dust in more efficient, however, according to the design cri­ southern arid and desert areas. Turner et al. (2013) teria the zeolite filter in the system was more efficient discussed the potential environmental risks of reusing than the pumice filter. greywater for irrigation, such as soil contamination According to WHO standards, the treated grey­ due to excessive contaminants present in greywater. water using all treatments was appropriate for irriga­ They concluded that there is limited influence on the tion of ornamental fruit trees and fodder crops (Table soil environment when irrigating with greywater. 1), where the residual BOD5 in treated greywater was Rather, the irrigation using greywater curbs the high lower than 240 mg L−1. Also, based on Jordanian volume of freshwater consumption for irrigation and Standards, all compounds were capable of treating the greywater provides nutrients for the crops or AUSTRALASIAN JOURNAL OF WATER RESOURCES 245 plants. Various field studies have indicated some dis­ irrigation of landscape, green areas in parks, school­ crepancies regarding treated greywater impact on soil yards, cemeteries, and golf areas. Therefore, this properties. Albalawneh, Chang, and Chou (2016) system can be implemented in public places such revealed that irrigation using treated greywater did as university, hospital, airport, hotel, shopping not have any apparent adverse effects on the key soil mall, restaurant, stadium, office buildings, etc. in properties after 2 years of practice at the studied the format of centralised wastewater treatment Jordanian sites. The average data of all locations plant or decentralised greywater recycling system monitored showed significant reduction in soil elec­ with connecting pipelines. trical conductivity (EC) levels and slight decrease of The findings from this study could serve for the organic matter contents. Sodium ions did not appear decision-making of countries that are exploring the to accumulate in areas irrigated with treated grey­ viability of greywater recycling projects, including water. Al-Hamaiedeh and Bino (2010) indicated that Iran, Kuwait, Saudi Arabia, Australia, and Malaysia, salinity, sodium adsorption ratio, and organic con­ and will expect to achieve higher water reclamation tent of soil increased as a function of duration of volumes in the future. greywater usage. An Australian research showed that salinity, SAR, and the organic content of the soil increased as a function of time and affected the Acknowledgments plant growth (Mohamed et al. 2013). In summary, the Authors would like to thank Water Quality Laboratory of aforementioned discrepancy of referenced studies Fasa University for providing the facilities to perform this might have been caused by the difference in grey­ research. water quality, which is very site specific and is diffi­ cult to predetermine or to control. In addition, the differences in climatic conditions, water evaporation Notes on contributors rate, and soil chemical and physical characteristics might be other causes for discrepancies. Also, Mzini Mehdi Bahrami received his Ph.D. in Water Engineering from Shahid Chamran University of Ahvaz, Iran in 2012. (2013) used treated greywater to irrigate vegetable His research field is mainly about environmental issues and crops and concluded that did not cause an accumula­ has published 40 international journal papers and 60 papers tion of salts and heavy metals in plants and soil, in scientific conferences mainly in environmental, pollution which suggested in this instance, that greywater did of surface and groundwater, and nanotechnology. He is not pose a threat to plants and soils. currently an Associate Professor of Water Engineering at Fasa University. Mohammad Javad Amiri received his Ph.D. in Water 4. Conclusions Engineering from the Isfahan University of Technology, Iran in 2013. His researches have been mainly about envir­ Three adsorbents (GAC, zeolite, and pumice) in the onmental issues. He has published 50 international journal format of a horizontal series filtration system were papers and 50 papers in scientific conferences mainly in tested for purification of greywater. The analysis of environmental, pollution of surface and groundwater, nano­ the data from the filtration tests showed that GAC technology, and artificial intelligence. He is currently an Associate Professor of Water Engineering at Fasa was the best adsorbent for removing COD, BOD5, and TDS from greywater, but pumice was more advi­ University. sable to remove turbidity. Morteza Badkubi received his M.Sc in Water Engineering Compared to other studies that evaluated differ­ from Fasa University, Iran in 2017. ent systems for greywater treatment, the filtration system used in our research had more removal effi­ ORCID ciencies of BOD5, COD, and turbidity. Nevertheless, based on the good wastewater purification perfor­ Mehdi Bahrami http://orcid.org/0000-0002-9935-7899 mance of the HSF, treated wastewater showed as Mohammad Javad Amiri http://orcid.org/0000-0002- a viable water source for non-potable reuse purposes 2633-0572 such as irrigation of orchards, pastures, cereals, and other crops through surface or trickle irrigation, References according to Iranian and Australian standards. Therefore, with proper management of the grey­ Abed, S. N., S. A. Almuktar, and M. Scholz. 2017. water irrigation system, reusing greywater for irriga­ “Treatment of Contaminated Greywater Using tion can fulfill the three pillars of sustainability: Pelletised Mine Watersludge.” Journal of Environmental ecological, economical, and social aspects. Management 197: 10–23. doi:10.1016/j. jenvman.2017.03.021. Additionally, this alternative source is applicable Aghakhani, A., S. F. Mousavi, and B. 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