Chapter 5: Overview of Treatment Technologies

liquid effluents. • and sludge; treated • screenings; • typesofendproducts canbedistinguished: three treatment, separately. andtreated After segregated at collected FS be should They 2. Chapter in described as concerns other or grease, and oil fats, of concentrations high of characteristics the have metals, with contaminated Also, be can they as checked be should technologies. facilities commercial and industrial treatment most preliminary for a needed trucks, transport is and collection screening by discharged FS the in paper and such tissues wastes plastics, coarse as of content high the Given FS. pretreated or digested or toilets), public from (e.g. fi different has FS undigested of co-treatment or treatment the for used be can They application. of elds In this chapter, an overview and introduction of FS treatment technologies is provided. Each technology of point the from collected be can facilities. FS treatment anddelivered to storage how described was it and given, was to mechanisms introduction treatment an discussed, were (FS) sludge faecal of characteristics the chapters preceding the In 5.1 INTRODUCTION • Understand the importance offi importance the Understand combinationoftechnologies nding acontext-adapted • and performance on based technologies treatment different contrast and compare to able Be • is information what and technologies treatment future potential of overview an Have • technologies. treatment sludge ofexisting faecal Have anoverview • Learning Objectives appropriateness for localcontexts. appropriateness and field ofapplicationfor technologies. treatment constraints advantages, the Understand implementation. reliable their for lacking currently Mariska Ronteltap, Dodane andMagalie Bassan Pierre-Henri Overview of Treatment ofTreatment Overview Technologies Chapter 5 97

Technology Technology matter into a stabilised form and/or pathogen reduction. The underlying mechanisms are described in underlyingThe described reduction. are mechanisms pathogen and/or form stabilised a into matter / liquid solid separation. Depending on the endgoal, treatment with further needs could combination include converting in organic or own, its on achieved be can which dewatered, be to needs hence and for enduse or disposal, several processes need to take place. FS typically large contains volumes of water conversion is safe 5.1. of forFS a into productthe that in realise that to Figure presented It is important treatment objectives and functionality,their with of together are treatment technologies, An overview TREATMENT TECHNOLOGY OVERVIEW 5.2 treated of fi value nancial the increase to goal alsointroduced are inSection5.4andChapter 10. technologies endproducts, andsomeofthese the under has currently research are current that this technologies of of range Much whole development. a is there Finally, 5.3. Section in covered are These addition. lime through treatment chemical and centrifugation, as such processes drying sludge management practises. This category includes anaerobic digestion of FS, sludge incineration, mechanical sludge and treatment wastewater sludge activated from adapted been have technologies other Several underSection5.2. chapter inthis deep rowdescribed Theseare entrenchment. and ponds; stabilisation waste in FS of co-treatment (MSW); waste solid municipal with together FS Technologies havethat also been of implemented and are relatively well are established co-composting of degrees respectively.7,9 6, and Chapter varying 8 in detail in described are which wastewater, their with co-treatment and on are based that technologies beds drying planted them treatment beds, drying unplanted FS tanks, settling are detail of level the of operational an in level covered book, same this all In the research. for of however, level available current FS; and not of implementation treatment is the information for operational available of technologies of number a are There and (FSM) management sludge faecal canbecompared.sewer basedtechnologies of costs how and technologies, of time life expected the over insight lastprocess in of section the technologies, chapter the costof offers this calculation appropriate of selection the in aid To estimation. cost reliable complicates further implementations treatment FS operational of experience a specifilong-term of context playlack strongly are the costsmoreover, and c; role factors many as obtain diffi to is cult costs the of cost overview of complete form a some However, comparison. without made be cannot technologies of choice a goals, treatment to addition In of1:2. FSataratio anddigested amixoffresh bedswith onunplanted drying experiments conducted CofiFS. digested with e fresh mix to is option Another fi step. digestion a rst with technologies, treatment of chain a to exposed be can FS fresh problems, these overcome to order diffidigestion (Heinss during mayand 3) and produceodors 2 (Chapter dewater to cult derived FS, fresh that fact from bucketthe or public a with latrines high to emptying frequency (once related per or month more is often), is more This the FS. pretreated or for tanks) septic from either (e.g. FS digested used be can some treating for suitable better are others toilets), public from application: (e.g. FS “fresh” of co-treatment or treatment of fields different have technologies Additionally, the further treatment of the resulting endproducts (either the solid part of • the treatment endproducts be can treatment this - systems sanitation onsite the from transported directly FS of treatment the • or technologies, endusegoals(seeChapter 10). ofcombinationsof: the willbecomprised Treatment the and regulations of existing context, local Selection the account 17). into taking done Chapter be should (see thereof, combinations Scheme Selection Technology the in detailed 5.1, further Figure are in and presented are endproducts and FS of combinations potential of Examples 98 (treated FS)orliquid effl(treated uents) before enduseorfi nal disposal. andproduces steps, solidandliquid endproducts; and done inoneorseveral . (2006) successfully (2006) al. et ., 1998). al., et In iue51 Grouping oftreatment technologies according to their treatment goal. are Endproducts discussed in Figure 5.1 regulations and local context are discussed throughout the Planning section of the book. book. Planningsectionofthe the discussedthroughout are andlocalcontext regulations local and chapter, the of end the at covered are feasibility economic as such technologies, selecting in elements key Other factors. playing role all account into that taking setting, particular a for technologies appropriate are selecting for assistance 17.10) provides (Figure scheme selection technology The (outside ofworker protection). role a play not do pathogens while important very is dryness incinerate then to production, energy is for goal sludge the the If reduction. pathogen and dewatering to paid be to has care particular then goal in mind (see Chapter 10). fiIf the nal goal is to make productcan a be that dry reused in agriculture, Chapter 3. One of keythe elements in designing any of series particular technologies is to keep fithe nal Untreated FS Legend Chapter inthisbook Endproduct/-use T reatment/goal T echnology Scheme ofChapter 17. Chapter 10.Specific fl ows from into onetechnology thenextispresented intheTechnology Selection thickening tanks Imhoff tanks Solid/liquid separ Settling/ ation 5.4 6 Dewatering drying beds dewatering Mechanical Unplanted Planted dryingbeds Thermal drying Solar drying LaDe 5.4 7 Pa Anaerobic digestion Sludge incineration Black SoldierFlies; further treatment ammonia addition vermicomposting with wastewater Co-composting entrenchment Stabilisation/ Co-treatment Deep row Lime/ 5.5 5.5 5.5 5.5 5.4 5.4 5.4 5.3 5.3 9 8 Fodder andplants Building material Soil conditioner Endproduct/ Irrigation P Biofuels enduse roteins 99

Technology Technology A carbon to nitrogen (C:N) ratio between 20-30:1 to ensure biological as organisms availability; the • and IWMI,2003): (EAWAGcontrolled be to need parameters following the process, composting optimal an ensure To ofclosedsystems. category composting inthe andisconsidered drum box called composting.is If feedstock waste untreated is placed is in called a this in-vessel closed or container which closed enclosures walled into put also Tocan decomposition. waste aerobic of for heaps effi space the left ciency, increase and windrows) (called heaps into up piled is matter organic raw are lower in and capital operating costs but typically require more space. In an open composting system, systems open which twoof composting closed, of are and types open There systems, fertiliser. organic benefihavea can which nutrients contains matter also conditioner.It soil a long-term as a used as be t can that organic stabilised is endproduct resulting The conditions. aerobic predominantly controlled Composting is a biological process involvesthat decompose that microorganisms matter under organic sludge Co-composting offaecal 5.3.1 ESTABLISHED FAECAL SLUDGE TREATMENT TECHNOLOGIES 5.3 100 s ece. h woe opsig rcs (nldn mtrto) ae a iiu o sx o eight to six of minimum ., 2002). al et (Klingel weeks a takes maturation) (including process composting whole The reached. is maturation phase the temperature the is around 40°C, and process the ends once ambient temperature During 50°C. to downdrops temperature the days, approximately30 After temperature. high of time this highestis during die-off process. Pathogen broken are bonds carbon when down exothermic an in released is heat as 60-70°C to rapidly rises temperature the heap composting operated properly a In A particle diameter of less than five centimetres for • static piles. Smaller particles degrade more rapidly A moisture content between 40 and 60 % by weight to ensure adequate moisture for biodegradation, • An oxygen of concentration 5-10% to ensure aerobic microbiological decomposition and oxidation. • During composting During carbon is to converted CO still of use make to available carbon, “robbing”thereby soil nitrogen the of nitrogen its and hindering availability thus forsoil plants. available any use may create soil can the in product activity fi compost microbial the nal as problems in carbon High slowly. proceed will degradation and cool remain optimal will heap hinders compost insuffiThe nitrogen. to ratio cient due populations C:N microbial Higher the of volatilisation. growth to due loss ammonia enhances nitrogen High structure. cell building for nitrogen and energy of source a as carbon need matter organic degrading particles sizeinflparticles for area degradation. aswell assurface andaeration structure uences pore pile size particles the through is aeration cannothindered strength if be Thus structural maintained. smaller with hand other the decomposition.on microbialfor But area surface providemore they as continuousbiologicalactivity. must ensure beaddedto dry,heaps becometoo water compost If 2002). high (Cooperband, space as pore the material, in air of the availability of the reduces content content moisture moisture the on primarily depends frequency turning the thus and vapour water removes Turning conditions. anaerobic creating saturated not are piles that and high to subject be will it where centre the temperatures. to moved is heap the of outside the on material that is to ensure turning main objective of this the although to better aeration, heaps can also contribute the turning manually or mechanically systems open In required. is energy external aeration forced With aeration). forced or active (called heap waste the through air sucking or blowingby enhanced be can or tunnels) (air structures ventilation passive providing either by ensured be can Aeration compost isstabilised. when the

and the C:N ratio decreases to a ratio of decreases to arounda C:N ratio ratio 10:1 and the canbelimitingifnotwhich available. skills, managerial and technical requires value with product safe a generating co-compostingand plant a 10).operating However,Chapter (see compostfor demand the on depending generation income for resulting the and conditions pathogen thermophilic inactivation. The output of the co-composting is by a good soil formed conditioner which provides is potential co-composting of advantage main The Potential advantages ofco-composting andconstraints opsig f acl lde n Mncpl rai Wse n Mreig ops (AA and (EAWAG Compost al . (2003). Marketinget al . (2008)andStrauss IWMI 2003)Rouse et and Waste Organic Municipal and Sludge Faecal of composting Co- publications: the including (www.sandec.ch), website Sandec the to refer content, moisture and (Konécompost piles in MSW with together mixed is 20% than higher content (TS) solids total a with FS sludge, dewatered of case the In wet. too gets system the before added be can moisture additional much nottypically so 40-60% of moisture a has already usually MSW Organic notpractical. therefore is wetand too compostis heap sprayed the beforevolume little and very of use the allow used only will content water high its be compostheaps, the over also can FS untreated Although beds). dewatering drying or undergone has tanks settling-thickening that (e.g. sludge with implemented best is MSW with FS of Co-composting sponge. damp a of feel the to limitsairsupply,Higher moisture content anaerobicinodoremissions. conditionsandresults creates corresponds which ideal considered is 60% and 40 between content moisture A considered. be must bioavailability lower for compensate to ratio C:N initial higher a used be can materials these all Although degradation. to resistant more also are cellulose of form tough a of made straw and stalks Corn degradation. biological to resistant are they as limited be should materials lignin high of Concentrations moisture. in low and carbon in high relatively be can waste municipal are as and relativelyexcreta urine high advantageous in nitrogen (see Chapter 2) and moisture, whereas mixing wastestreams different together. For example, mixing of FS and forMSW co-composting can be by achieved be can content moisture and ratio C:N appropriate with conditions composting Optimal based compost. which is an acceptable range. A large number 70-100%,(83%) of were farmers interviewed willing between to use excreta- varied capacity germination the and vegetables selected of capacity germination the on impact its for tested was compost The 5.1.Table in provided are details more - reuse to prior stored sampling and bags kg 50 and in packed sieved, weighing was compost matured The analysis). measurement, laboratory by (followed temperature watering, turning, out: carried were activities using an open windrow system (aeration by manual turning). During a composting composted cycle, and the 3:1 following of ratio a in mixed were FS dried and MSW the of fraction organic The used. was composting site, the to bydelivered trucks and frommarkets collected areas, residential waste or solid (about 10 days) and stored to prior co-composting. For waste, organic the fraction organic of municipal and septic FS tank ratio of 1:2. The FS dried was removed from beds the drying once it became spadable toilet public of mixture a in beds the to applied was FS The composting. aerobic direct for unsuitable is FS fresh content, moisture high its to due as beds, drying unplanted in fi was dried sludge rst site, in plant For project the On Kumasi. in the tanks septic household and to toilets MSW.public unsewered from collected delivered trucks, was organic FS chosen. was with plant treatment co-compostingBuobai the of of facility the operation location the subsequent the and bed an drying in drying unplanted sludge study to Ghana Kumasi, in opened was plant pilot research a 2002 February In from(Adapted Cofie andKoné, 2009) Case Study sludge andorganic 5.1:Co-compostingoffaecal solidwaste inKumasi, Ghana ., 2007). For further guidance on ensuring optimal carbon, nitrogen carbon, optimal ensuring on guidance further For 2007). al., et 101

Technology Technology 2 Facultative ponds that are 1 to 1.8m deep allow for remaining suspended solids to settle. In the top top the In settle. to solids suspended 1.8m remaining forallowto deep 1 are that ponds Facultative and 2 solids suspended of settling for used are deep meters four to two are that ponds Anaerobic 1 5.2): (Figure treatment wastewater in implemented frequently is series in ponds of types three of combination A times. andretention depths different having ponds several of consist WSPs 2004). (Mara, climates tropical in particularly available, is land adequate when countries low-income in treatment wastewater for options good be to WSPs considered are ecosystems. aquatic in occur that processes natural on The based are wastewater. stabilisation municipal for of mechanisms treatment the for used widely are (WSPs) ponds stabilisation Waste Co-treatment inwaste ponds stabilisation 5.3.2 102 prevalent at the bottom. atthe prevalent are anaerobicaerobicallyconditions while is pollution digested, dissolvedpond organic layerthe of subsequent anaerobic digestion. Theeffluent fl pond. facultative the to ows s cnmcly ibe hwvr dpns n aiu lcl odtos se hpe 1 fr issues for 10 Chapter (see conditions local ofendproducts). economicfeasibility regarding various on depends however, viable, economically is is FS dewatered of composting that concluded technology the Whether be agriculture. in foruse safe conditioner soil a in results it possible; technically can it investigation, described above the From enduse. to prior storage case,onepossibilityisextended WHO guidelines.Inthat the meet to adequate be the not will reduction pathogen met, not are conditions during these if that Note . 45˚C generation heat to due over temperatures to month one days than more for eggs helminth the exposing thus composting 80 process, after Ascaris reached High egg/gTS. was Ascaris (90–100%) effi 1 ciency of inactivation guidelines WHO the with complied necessary that was compost months produce 2 least to at of period composting optimum an eggs, helminth to regard With al . Design criteria and assumptions, used for the pilot-scale unplanted bed and co- sludge drying Table 5.1 Volume ofFS treated produced Dried sludge beds Hydraulic loadon drying beds drying sludge Surface sludge septictank sludge: Ratio publictoilet FS sludgetruckloads Dewatering cycles Faecal sludgedewatering composting plantinKumasi, Ghana(Cofie andKoné, 2009) 45 m 1.5 m 30 cm/cycle 50 m 1:2 3 percycle(1truck~5m 3 permonth day 2 3 3 /month =1.5m /cycle 3 / 3 ) Raw compostproduced through co-composting Volume reduction Composting cycle Required volume MSW produced Mature compost Composting time Ratio MSW:dried FS Co-composting 4.5 +13.5=18m 50% month One starting eachmonth One starting 3 ·4.5=13.5m month (density 0.5t/m month (density 9 m months maturation 1 monththermophilic; 1-2 3:1 (by volume) 3 /month =4.5tonnes/ 3 /month 3 / 3 ) • Leachate from unplanted and planted drying beds. Leachate is low in organic matter compared to to compared matter organic in low is Leachate beds. drying planted and unplanted from Leachate • including: technologies, FStreatment products ofother landfi (Kurup with leachate FS ll of co-treatment the for used be (Strauss quantities large of addition the is nor recommended, not is WSPs in FS solely treating content, solid and loads organic high and concentration ammonia high the to due infl However, wastewater uent. problems were the observed when dosing to FS to comparedthe anaerobic pond volumes and dosing was small discontinued. Typically, in only but screening, after directly Papadopoulos tanks. settling-thickening in FS of separation solid-liquid effl the with following uent wastewater of co-treatment the for used be can ponds stabilisation Waste ponds are 1-2 m deep and loaded with 350kgBOD/ha/day (35gBOD/m 1-2m deep andloadedwith ponds are 60-70 % of BOD and produce limited odor when loaded with 250–350 gBOD/m 250–350 with loaded when odor limited produce and BOD of % 60-70 remove haveAnaerobicponds depth, m 2-3 rates. loading fordesigned organic are ponds Stabilisation ammonia the lower to helps also al.,2000). et (Strauss which concentration oxygen, adequate ensure to implemented be can aeration mechanical or Cascade factor. limiting a becomes quickly ammonia WSPs, to FS of addition the With Maturation ponds that are 1 to 1.5 m deep allow for pathogen reduction and stabilisation. The ponds 3 Design ofpondsconstituting andprinciples ofthethree waste types stabilisation ponds(Tilley et al., Figure 5.2 rcin s eaiey o. oee, h amna ocnrto cn tl peet polm and problem, a inhibitionby ammoniacanalsooccur(asdiscussedabove). free andmethanogenic algae present still can concentration ammonia the However, low. relatively is fraction solid the as possible be might pond facultative the into discharge direct and wastewater domestic occurs via UV rays from the sun. from the viaUVrays occurs are mainly aerobic. Oxygen is supplied through algae and diffusion from air.the reduction Pathogen 0.5 m - 1.5 m 1m - 2.5 m 2 m - 5 m 2014). liner inlet inlet inlet 1 anaerobic 0 0 2 2 0 0 2 2 0 0 2 2 0 0 2 2 2 facultative 1 anaerobic 3 aerobicmaturation 2 facultative oxygen supplythroughsurfacecontact+algae sludge oxygen supplythroughsurfacecontact sludge ., 2002), and can treat liquid by- liquid treat can and 2002), al., et 3 aerobicmaturation . (2007) also applied FS applied also (2007) al. et 2 ., 2000). WSPs can also can WSPs 2000). al., et ., 2002). al et Klingel /day; 3 /day. Facultative Facultative /day. outlet outlet outlet 103

Technology Technology a mn bnfit sc a eta CO trees expensive growing extra no addition, as it: In such benefi maintenance. for manyts poor needed has to is susceptible little very are very that that pumps is or entrenchment infrastructure row deep of advantage main The Potential advantages ofdeeprow andconstraints entrenchment foreseeable future. pilot scaleinthe at the for regulations example, will environmental only allow deep row forentrenchment pit sludge disposal Africa South in option; this for lacking still is legislation manycountries In areas. peri-urban and rural source and where sufficient land is available, which means sludge the would have to to be transportable considered most feasible in areas where the water supply is not directly fromobtained the groundwater that the fast growing trees took up the additional nutrients (Still in the area showed that surrounding bodies groundwater remained free from pollution. It also appeared soil and conducted tests found in the was leaching nitrate application in Durban, limited bodies. In the groundwater clean to distance/depth the is as row deep entrenchment, with majora constraint is land of availability However,the trees. of Benefiproduction nuisances. increased the from gained also are ts present a solution is that simple, low cost, has limited O&M issues and produces no visible or olfactory slowly released from the FS. In areas where there is adequate land available, deep row entrenchment can are that nutrients and matter benefi which organic top, on the from planted t then are Trees soil. with Deep row entrenchment consists of digging deep trenches, fi sludge lling with and them them covering (Still Africa South Durban, in FS for adapted been has 1980sand the in US the in sludge also covered in and Chapter is 10.therefore Deep implementedrow was entrenchment for wastewater a and treatment enduse option,can be as considered both Deep row that is a entrenchment technology Deep row entrenchment 5.3.3 that sludge of removal The al.,2000). anaerobic et pondsmay heavy require equipment mechanical (Strauss inthe accumulates concentrations. ammonia and salt high to due inhibition performed, not potential is and separation solids preliminary if accumulation solids of rate high availability, land for tropical climates, and achieves relatively high removal in efflpathogen the uent. Constraints include WSPs are simple to build and require relatively low O&M requirements. The technology is appropriate Potential advantages ofwaste andconstraints ponds stabilisation with co-treatment as Argentina in implemented was This Effl tanks. settling-thickening from uent • 104 al.(1999). et Strauss Mara (2004), Mara in found be can design, including WSPs, on reading detailed More and, moreover, legislation still needs to catch up in many countries to allow for this technology.and, moreover, allow to for this upinmany legislationstill catch needsto countries table groundwater enough low a with area an suffiin available that be are to Constraints has land cient settling ponds (Fernández settling ponds (Fernández effl the of treatment the from for influent conducted were the tests where ponds, anaerobic of uent s otetd ih atwtr n WP ad h tiknd lde s eaee wt unplanted with dewatered is sludge beds. drying thickened the and WSP, a in wastewater with co-treated is effl the tanks, settling by done uent is separation solid/liquid preliminary where Senegal, Dakar, in ., 2004; Ingallinella Ingallinella al., 2004; et 2 ain eoin rtcin o ptnil cnmc benefits. economic potential or protection, erosion fi xation, et al., 2002). et This solution has also been adopted et al., et 2012). Deep row entrenchment is . (1992) al. et and ., 2012). al., et conditions. speciesandexperimental dependingonthe differences substantial where Still 5.4; (Figure of south Umlazi, in operation Durban, in project started 2009. Pit sludge latrine at was buried loading different in rates EWS sandy soils The (VIPs). latrines pit improved ventilated from derived FS and treatment wastewater municipal from sludge both of treatment and disposal for entrenchment row The water and sanitation unit (EWS) of the eThekweni municipality in Durban has been pursuing deep al.,2002) from et (Adapted Still Case Study 5.2:Deep row entrenchment inDurban,South Africa et al.,2012). et Still orinfection, were found still to beviable(capableofgrowth 0.1% than less entrenchment of years 2.8 after sludge, latrine pit exhumed freshly in found were ova were also monitored. The researchers South African found that while a significant number of helminth Ascaris nutrients, to addition In increase. substantial a still is which obtained, was biomass more 40% to 30% a only cycle growth was year nine increase the of end 300% the at a while FS year with growing one trees the for After observed time. over reduced was controls and sludge with between grown growth trees in difference relative the that observed was it Durban near site testing second a At Figure The Umlazi Deep5.4 Row Entrenchment Test Site – top the sludgeburial of faecal from pit latrines Jay Bhagwan, WaterJay Bhagwan, Research Council, South Africa). Groundwater wells were mappedto follow thefate ofnutrients, organics andpathogens (photos: in 1mdeeptrenches; below anoverview ofthefi picture lled trenches with trees planted ontop. , 2012). Positive effects were seen on the trees that were planted, however, there however, planted, were there that trees 2012). al., the on seen wereet Positiveeffects 105

Technology Technology solubility of salts, and inactivation of pathogens. ofpathogens. solubility ofsalts,andinactivation and exchange gas as such reactors in parameters chemical and physical affects also temperature time, same the At formation. hydrolysisof methane and rate and degree the especiallyrole,on important an plays also temperature The failures. reactor prevent to HRT the of track keep to important therefore is It 2003). the Eddy, and in (Metcalf decrease methanogenesis or and increase acidifi hydrolysis,an fermentation of to cation, leads degree HRT the in decrease or increase an HRT: the of length the to recycling, without systems related directly For are steps occur. reaction flanaerobic plug The (e.g. to HRTreactors). ow the to equal degradation is SRT for the HRT enough long a for allow to order expected, in be can that load organic the know to important is it reactor, anaerobic an designing When elements. andtrace ofnutrients bioavailability • and toxic /inhibitingsubstances; • pH; • alkalinity; • temperature; • HRT; • time(SRT); solidsretention • the (HRT), include: ofanaerobic digesters and operation time design the retention in role important hydraulic an play that the conditions Operating pattern. are loading the and digesters temperature anaerobic for parameters design main The developmentofanaerobic future digestion ofFS. potential for the great is There untapped. remains still areas urban in FS of treatment centralised to semi-centralised for (Koottatep practised widely is FS of addition the without or with Arthur agro-industries, (e.g. plants treatment wastewater loaded highly and wastes industrial for developed and known well also blanket is treatment fiAnaerobic sludge anaerobic and lters. baffl(ABRs) anaerobic upflanaerobic reactors reactors, ed (UASB)ow include also technologies stirred treatment continuously Anaerobic or fl (PFR)(CSTRs). plug ow reactors with typically sludge, activated waste and of sludge digestion primary the for facilities treatment wastewater centralised in applied widely been has digestion Anaerobic digestion treats organic waste in airtight chambers to ensure anaerobic conditions. Anaerobic 3and10. provided anditsuseare inChapters of biogas fundamentals on information More conditioner. soil a as used be can and stable biologically relatively is digestate the and dioxide carbon and methane mainly of mixture a is Biogas digestate. or slurry as to During anaerobic digestion, organic matter is converted into biogas and the remaining sludge is referred Anaerobic digestion 5.4.1 given are pertechnology. details More to FS has not been researched in yet, much detail which is key for implementation. succesful long-term regarding present is knowledge much and years design, operation and maintenance. The many diffi for culty is however applied application the that of technologies these been generally have they that is benefiThe FSM. in application to transferable maybe technologies there applied typically are these of t treatment produces sludge needs sludge Activated waste wastewater that treatment. Technologies that SLUDGE TREATMENT TRANSFERRED TECHNOLOGIES 5.4 106 (2011) Kamaraj and Daisy excreta, fresh of digestion anaerobic the Arthur For size. digester consequently, the excreta. and FS of digestion anaerobic the (2011) Klingel and evaluating studies few a been have There sludge withExperience faecal . (2002) recommend preliminary thickening to reduce the sludge volume and, volume sludge the reduce to thickening preliminary recommend (2002) al. et et al., et 2011). Throughout Asia, the onsite anaerobic digestion of animal manure ., 2004). However, the potential However, the 2004). al., et et al. et velocity and prevent scum from leaving the system. The sludge accumulates in the sludge digestion sludge the in accumulates sludge The system. the leaving from scum prevent and velocity reduce to outlet the and inlet the at bafflused or are pipes es T-shaped layer. scum a creating surface, water the to particles sludge transports gas The compartment. digestion the into centre the to down settling The top. the to compartment rises has inclined walls (45° process or more) and digestion a slot at anaerobic the bottom, which allows the the sludge to slide by produced biogas and bottom settles the sludge where at sludge) wastewater for meters nine to (up tank high-rised a is tank Imhoff The underanaerobic digestion apply here. were described system separation solid-liquid a as including partial serves digestion for the settled sludge. it The same considerations for sludge that where characteristics treatment wastewater in technology treatment primary a as used often most are tanks Imhoff treatment. FS for Indonesia in implemented been has and treatment wastewater for well-known is which system compact a is It 5.5). (Figure one in system digestion anaerobic an and settler a of effect the combines that tank sized compact a is tank Imhoff An Imhoff tank 5.4.2 technology.application ofthis sustainable and safe the about more learn to order in implementation scale full to prior installed be to need facilities scale pilot and needed, is research further Hence, to areas. urban semi-centralised in in treatment centralised alone FS for proven amount been yet vast not the has it despite digestion, anaerobic that, on is knowledge of treatment A FS level. for household technology the a at as addressed digestion anaerobic be of should constraint metals heavy and detergents also and FS, of nature inconsistent the to due considered be to needs digestion of Inhibition operation. skilled of level relatively high a requires digesters anaerobic of (O&M) maintenance and operation However, odors. and volume sludge reducing FS, stabilising while biogas produce to potential the has digestion Anaerobic Potential advantages ofanaerobic digestion sludge andconstraints formanagement faecal production could be higher if operating conditionswere optimised. production couldbehigherifoperating gas that indicates This 50-60%. is a reduction theoretical represented the whereas only solids, volatile production of reduction 30% gas the However, respectively. 30°C to 15 over produced be can FS enough long a Song if possible, chosen. well is very time is retention viruses hydraulic and bacteria of reduction that review their in report iue55 Schematic representation ofanImhofftank (Tilley et al ., 2014). Figure 5.5 cleanout pipe outlet sludge cross section compartment settling flow tank/ compartment digestion sludge . (2012) found that between 15 and 90 mL biogas/g biogas/g mL 90 and 15 between that found (2012) al. et bubbles gas scum plan of flow direction baffle inlet baffle outlet scum 107

Technology Technology Potential advantages ofsludge andconstraints incineration with co-incineration and incineration fluidised-bed incineration, municipal solidwaste. multiple-hearth are systems incineration used Commonly 2003). Eddy, and (Metcalf sludge the of content it volatile as the necessary decreases not is treatment stabilisation but combustion, to prior dewatered be to needs Sludge (Hall,1999).metals heavy of concentrations high contain may ash the sludge, of landfi source in the on Depending sites. ll for example as a toilets fordiversion cover or dry urine in material or construction, it can be disposed of Muspratt Murray – however, 10 Chapter recovery,(see kilns cement resource in example for for sludge, of potential incineration the from the captured be of can energy advantage take typically not does It 850-900°C. Incineration of sludge is a form of disposal which involves the burning of sludge at temperatures between Sludge incineration 5.4.3 al.,2010).et (EAWAGdesign the to according removed be should compartment digestion the of bottom the from sludge Stabilised important. very is scum of removal the as well as tank the flof of Cleaning sides the operators. paths, ow skilled requires it but technologies, some as complex as not is system Imhoff an of maintenance and Operation frequency. draw-off inadequate an of case in pipe draw-off sludge the to damage of risk baffl the inclined and the es, accommodate to elevation additional an require to tanks compared constraints main Imhoff The the as costs higher complexity,slightly fraction. operational increased the are liquid tanks thickening settling the and land sludge (Klingel settled small tank the the one between are only separation tanks operating settling-thickening of to possibility compared the tanks requirement, Imhoff of advantages main The Potential advantages ofImhofftanks andconstraints system. the disturbing from material coarse prevent to tank Imhoff the to prior recommended is chamber grit or screen bar A 5.5). Figure see 2007; (WSP, added be can desludging for outlet an tank; the of sides the at located are chambers vent gas and Scum times. all at ensured be to has chamber settling the of slot and mobile pumps (see Chapter 4). A minimum of clearance 50 cm between sludge the blanket and the trucks vacuum for provided access or installed be to havepump and pipe a desludging, For gravity. by done be can it because easier removal sludge makes which ground, above built be also however, can, It concrete. reinforced with underground built usually is tank Imhoff The needed. is volume greater a therefore, and, suffitime for allowretention sludge longer climates colder In digestion. anaerobic cient to capacity storage sludge 12months to four for designed and usually is chamber digestionfrequency. The temperature the on mainly depends of which sludge are degree stabilisation, linked sludge desludging to accumulation the targeted and the compartment digestion anaerobic the of Dimensioning pondsisnot available. orspacefor stabilisation digesters for biogas notare favorable liquid can be treated in for example a constructed wetland. An Imhoff tank can be used when conditions the bed; drying sludge a on or tank thickening - settling a in treated further be can sludge The enduse. fibefore or disposal treatment nal further digestionneed sludge settledthe the in and years supernatant several the to Both up chamber. remain can solids the while hours) 4 - (2 time retention short a has anaerobic digestion. The liquid fraction through chamber, and is compactedstabilised and partially 108 2003). Eddy, and (Metcalf ashes residual removed. are andallpathogens reduced volume sludge issubstantially the and that are Advantages costs; O&M and operating skilled capital highly high for staff, need maintenance the and pollutants; of emission potential the include: Disadvantages ., 2014). The ash that is produced from incineration could potentially be used, be potentially could incineration from produced is that 2014).ash al., The et , 02, n te physical the and 2002), al., et n oeainl ot, n mnml aneac sil ae eurd Hwvr te eaeig is dewatering the However, required. are skills technologies. dewatering mechanical other comparatively lower than maintenance minimal and costs, operational dewatered The and equipment cylinder. low relatively at the dewatering in provide presses pores Screw end. the other the through at discharged removed is sludge is out squeezed is that liquid the and cylinder, the and screw the between distance diminishing a to due pressurised is it end, one at loaded is sludge The cylinder. perforated a in placed screw rotational a of consists press screw A press: Screw lower wall). openingofthe the through beingreleased sludge dewatered andthe frames porous chamber at (up 15high to pressure the the being through released leachate in resulting the bars fiis sludge into lled the which in process batch a is This chamber. a create to other the of one front in fiFrame lter press: This system consists of fiporous frames vertical xed in twoare positioned that walls transports another requirements. highenergy while isthe centrifuge ofthe entered, end.Themaindisadvantage other the to sludge the sludge the where side the to Archimedean liquid An released surface. the the transports against screw outward the pushed into are injected particles is the and fl sludge cylinder, The occulated this force. of middle centrifugal the to due axis, horizontal its around Centrifuge: This FS the technology as dries it is squeezed outwards of on a surface the cylinder rotating isreleased. sludge dewatered andthe separated beltsare the azonewhere • sludge, and compresses upper layer a compression a secondof zone beltthe where is applied on the • and porous a on conveyed and deposited is fl sludge the occulated where zone drainage gravity a • diffi andthe needfor skilledmaintenance the are consists of: Thesystem culty incontrolling odors. belts. The main of disadvantages a belt fi lter press compared to other mechanical techniques dewatering Belt fi lter press: This allows water to the be squeezed out of sludge the as it is compressed between two for FStreatment. systems ofsuch canbemadeondesignandoperation recommendations are required before experiments are widely sludge, further used they for treating Although wastewater particles. solid the from liquid of separation the flof facilitate to them of all for recommend is occulant The following addition are technologies well management, and recognised preliminary for wastewater In transferable. is technologies. for landintensive more no spaceavailable technology the theoretically but screening FS, and is FS addition used after of to dewater flMalaysia, centrifugation is occulants where there to technologies these the for literature of the in implementation available are examples few Only press. screw the and fi press, frame lter the fibelt the are sludge WWTP widelycentrifuge, are for used dewatering lter,the that technologies Four pressing. or or by processesnaturally machine as such centrifugation can be done either and this necessary often is content water the of reduction additional process, thickening sludge the After managed. or treated further be to needs that sludge of volume the reducing for important are thickening and Dewatering steps. treatment other following or to, prior out carried be can thickening or dewatering Mechanical 5.4.4 sludgeMechanical treatment treat FS, information from manufacturers, laboratories, andpilot-scale isnecessary. tests laboratories, from manufacturers, FS,information treat are compactness,the advantages and speed the of process.the To transfer types these of technologies to costs, the O&M requirement, the need to add flocculants and the dependency on electricity. The general The main constraints of these technologies in comparison to non-mechanical options are the investment Potential advantages sludge ofmechanical treatment andconstraints it to a pressure that can reach 7 bars; and 7bars; canreach that apressure it to mobile belt; 109

Technology Technology CaO+H Equation 5.1: calcium or lime, hydrated as known also lime, slaked hydroxide get (Equation 5.1; BiosolidsTechnology Factsheet). to hydrated then is quicklime process; h hg p de o h frain f CaHCO of formation the to due pH high The equipment. Therefore, observed. are system and safety whoprocedures is mustand required make follow use of good protective health respiratory skilled staff with and strongly skin eyes, reacts the which to hazard material of alkaline risks an high and is moisture Lime concern. a also is regrowth Pathogen area. requirement technique of are of the this The consumables main (lime), disadvantages and storage a dry Potential advantages oflimetreatment andconstraints Equation 5.2:Ca(OH) Ca(OH) lime slaked and (CaO) lime quick are forms common most Its lime. as termed generally are properties havealkaline highly which compounds chemical All amount. dosing higher and time contact longer a by enhanced is effect Its 2005). Nelson, and (Pescon concentration ammonia and reactions) oxidation exothermic (through temperature pH, of increase an on based is stabilisation alkaline during reduction pathogen of process The 5.3). Study (Case treatment FS for Philippines (Méndez the implementedin been has and 2002), phosphorus and metals precipitate to conditioner sludge as also and matter, organic Lime is used for sludge wastewater treatment to achieve the reduction of pathogens, odours, degradable Lime addition 5.4.5 110 fi andmoisture mustre beensured. personal protection equipment (PPE) protection is (see from crucial also Case Study 5.3). Furthermore, soil other and composting as such processes. processes Moreover, safety as is microbiallime very important: is corrosive to the skin, eyes desired and lungs and proper affects also lime of effect removing pathogen the However, lime. the with precipitate can metals heavy that is benefilime added of An t way 2006). andMathai, possible (Turovskiy economic most the in stabilisation lime from results optimum achieve to contact order isdose, in pH lime and it time characteristics, However, sludge like 2006). parameters design Mathai, of number and a (Turovskiy consider to matter important organic of degradation microbial retards or In the start-up of the study, one load (approximately 5m (approximately study,load one the of start-up the In fi notbefore inthe tested (DOH)butitwas ofHealth Department Philippine’s eld. the in tanks septic from by the technology also mentioned as an appropriate Philippines (Robbins,FS was 2009). Lime treatment determine domestic treating to of project method Environment a demonstration as Planning, stabilisation pilot lime of a Health, effectiveness of the City stage fi Fernando rst the San in the engaged offices from Engineering and staff and engineers 2008, June In from(Adapted Robbins, 2009) Case Study 5.3:Lime inthePhilippines, stabilisation San Fernando Valley areas; 2) the groundwater table is more than 25m below the testing site, and 3) preferably the soilis the and3)preferably site, testing 25mbelow the than ismore table groundwater 2)the areas; site is 1) at the a site had suffito be followingselected, using the criteria: from cient residential distance 2 Qikie s eie fo lm soe y hg tmeaue calcination temperature high a by stone lime from derived is Quicklime . 2 2 O →Ca(OH) +CO 2 →CaHCO 2 3 +H 3 Euto 52 cets n niomn ta halts that environment an creates 5.2) (Equation 2 O 3 of FS) was used in a test run. First, a proper a First, run. test a in used was FS) of et al., et proper conditions the technology of vermicomposting can lead to a complete removal of coliforms. coliforms. Rodríguez-Canché of under removal complete out a to carried lead can when vermicomposting However,of technology removal. the conditions pathogen proper adequate ensure to method reliable Vermicomposting vermi-compost. a and not soil of is layers of form the in support of kind some need and fifunction communities the in within bacterial synergy with lter. Worms cannot in survive fresh faeces (Zhao earthworms with inoculated system a in sludge wastewater domestic diluted treats “vermi-fi which the lter”, is example An reduction. waste organic in effective very be to appear they and sub-class oligochaetes the of member a are Earthworms 5.5.1 Vermicomposting Chapter 10,with Products. EnduseofTreatment link strong a has therefore section this and recovery, resource incorporate innovations these of Many technologies. treatment FS innovative on conducted being research of of deal great a currently is There INNOVATIVE TECHNOLOGIES FOR FAECAL SLUDGE TREATMENT 5.5

0 g a, nldn dlvr. aig no con to mlye, oioig ecvto and m excavation monitoring, employees, two account per USD) into (4 Pesos Philippine approximately200 was treatment forcost total the costs, miscellaneous Taking per USD) delivery. (9 including Pesos Philippine bag, 455 kg was lime 50 hydrated the of cost the study, Fernando San the For irrigate to used be landfiand usedfor example asacover for sanitary then lls. could it and pond leachate dried or amendment soil a as applied maybe solids The purposes. landscaping for or land, a agricultural to discharged and off clear siphoned the hours, was 24 liquid After neutral. toward again decreased pH the completed, was process the After Philippines. DOHofthe limitsset by the allunderthe levels remained the that revealed content metal heavy as such parameters other on Tests performed separation. liquid as well as observed a was (pH proper 11 solid destruction full pathogen period, that for 2 After hours). FS loads up to 15FS loadsupto m 5m per lime of kg 50 of rate application m per used lime of amount the upon depend will pH the of level ultimate the and rise pH the of speed 11.pH The at minutes 11.5;120 pH or at minutes 60 12; pH at minutes 30 achieved: be to had goal following To the disinfection, properwatch. stop a reach and monitor pH handheld a with monitored was treatment the of progress The truck. the of tank the into directly lime the add to be could mixing of way alternative an that span suggested is time It mixing. This of level paddles. desired wooden the suffi reach be large to to cient proved with minutes 30 for suspension in lime the kept three operators to two performed: was mixing manual available, was pump mixing horsepower three small a Although FS. the into mixed was lime the Then powder. reactive the in breathing prevented workers the masks dust wearing by and time a at shovel-full one manually added was lime The bags. kg 50 in supplier the by site the at delivered was Lime mixed. and added was lime level, required the to pit the to testing FS the and site was transported bydumped truck, into pit the in one fiAfter off-loading. lling 4 by wide meters 3 was and meters landfi long.Thesoilsatthe 1.5meters of required. hencenolinerwas highinclayll are particles, depth a to excavated was study Fernando San the in pit identifi was site to this impermeable reduce lining costs. After ed, a The mixing created. mixing pit was 3 3 of FS treated. The results, costs and applicability make lime stabilisation a feasible technology for technology feasible a stabilisation lime make applicability and costs results, The treated. FS of an that show trials Fernando San The mixing. the and lime, hydrated the of quality the FS, of . (2010) found helminth egg removal in experiments with vermicomposting with experiments in removal egg helminth found (2010) al. et 3 . 3 of FS was adequate to achieve the required level of treatment treatment of level required the achieve to adequate was FS of ., 2010). Interestingly, the earthworms seemed to to seemed earthworms 2010). al., Interestingly,the et 111

Technology Technology iue56 Black Soldier fl (photo:y pre-pupae Stefan Diener). Figure 5.6 produce asoilconditioner. to digested anaerobically or composted further be to need feed larvae BSF the after remaining residue FS 10).The Chapter (see farmers to feeding animal as larvae the of selling the for advantageous be can This production. mass larvae faster and higher achieve can waste solid municipal and FS of mixture a Diener however, FS; on solely well grow to shown been have larvae BSF isnot produced continuously.waste when even wastes of treatment the for allows thus and food, of availability the on depending months (Diener phosphorus and nitrogen as such nutrients of removal the with together 75%, to up of volumes waste organic of reduction rapid flcan (Sheppardit y when matter organic low, by decaying very is notis it as attracted forvector transmission a disease being BSF the of risks the stage, larval then for migrate pupation, and do not feed anymore, even during the adult stage. Therefore, of cycle growing natural the on relies 2011).process al., This such as municipal animal solid manure, and wastes, FS (Diener manure. The Black Soldier fl wastes of haveorganic y been (BSF) investigated degradation larvae for the or fruits, and vegetables as such material, organic decaying on fl feed The climates. larvae y warm and temperate in found commonly is but America, in floriginated Soldier illucens) Black (Hermetia The y Black Soldier fl5.5.2 ies be benefi isa marketcial provided for there them. can composting. worms of production The forthermal than longer compostbe can matured reached is timespanuntil andthe susceptiblebe quite toxic ingeneral), components to (orhigherconcentrations treatment further steps are required. Constraints are treatment, that the technology is still in development; the worms during can achieved not is reduction co- pathogen adequate for if pointsTherefore co-composting.of temperatures the thermophilic to the at similar out are carried be vermicomposting cannot vermicomposting forHowever, composting. constraints and advantages the general, In Potential advantages ofvermicomposting andconstraints weight<1000 basis,respectively. onadry MPN/g,<3and<1viableova/g inoculation, initial faecal coliforms, Salmonella the earthworm spp., and ova helminth were reduced to from starting days, 60 after achieved were agriculture in reuse for levels Permissible FS. tank septic on 112 ., 2009). This growth stage can vary from two weeks to four to weeks two from vary can stage growth This 2009). al., et ., 1994). During their larval stage, BSF larvae achieve a achieve larvae BSF stage, larval their During 1994). al., et which need to feed only during the the during only feed to need which BSF et al., 2009; Diener et . (2009) observed that that observed (2009) al. et et al., 2011;et Qing et et f moim (NH ammonium of ammonia in the form of the synthetic urea can be added to enhance the treatment. treatment. enhancethe canbeaddedto urea synthetic ofthe form ammonia inthe additional concentration, ammonia low with sludge For 2). (Chapter concentration ammonia high a reduction in FS. This can be done by collecting separately,urine and mixing then it FS, with as has urine pathogen for excreta from ammonia the using on conducted been have investigations recently, More is it where sludge, al ., 2002). al.,1994;Mendezet et (Allievi stabilisation asalkaline to wastewater commonly referred for applied been has sludge to addition Ammonia 2003). Gonzalez, Ammonia treatment can be applied for pathogen reduction. Pathogen inactivation by uncharged uncharged by inactivation Pathogen reduction. pathogen (NH ammonia for applied be can treatment Ammonia Ammonia treatment 5.5.3 al ., 2011). cannot begiven technology for (Dieneret FStreatment this of middle-income operation and design and the on recommendations precise low- therefore and available, in yet not is countries experience upscaling on information However, investment. minimal with entrepreneurs small for generation revenue allows It scale. small a on and wastes, organic other with mixing without or with achieved be can it that is FS of treatment for BSF using of advantage The Potential advantages ofBlack Soldier fl andconstraints ies and sustainability of the technology. Another constraint is the stability of nitrogen in treatment treatment in nitrogen of stability the is benefi fullnutrient constraint the endproducts, andwhether t canbeachieved. Another technology. the of sustainability and seems It feasibility economic the limit may which higher, conditions. become costs the applied, be to needs urea synthetic storage stringent where cases the less In (UDDTs). toilets dehydrating requires diverting urine with areas ammonia in applicable particularly treatment, lime to comparison In Potential advantages ofammoniatreatment andconstraints is based on the fact that ammonia (NH ammonia that fact the on based is (Jenkins larvae as protein source) make it a promising technology. Some technical as well as entrepreneurial entrepreneurial as well questions however still beanswered. are to as technical Some technology. promising a it make source) protein as larvae sale for product the dried (crushed potential market preparing the and and technology this of costs larvae operation (www.biocycle.com).Low the harvesting facilities, their collecting at by it model treating business profi waste, a human table upscaling For on developing. working be is to companyseems market Biocycle the Yet, the scale. example, laboratory a at been has far so work the of Most FS without additionaltreatment. FS without suffi the be sanitise may ammonia to cient intrinsic fl the low volumes, and water storage ush airtight use lower. which implementing By systems toiletconcentration ammonia required the and faster was eggs Ascaris of inactivation the temperatures, higher At 23°C. at required was storage months 6 and mM) (44 lower were concentrations ammonia the use, fland For person per L 6 of volumes water ush flL 2 to corresponds this - use. and 1.5 person month per within achieved be water could ush viability egg Ascaris of reduction and 99.9% 23°C, and concentrations 170mM above concentrations ammonia ammonia At different temperatures. at scale laboratory at storage during FS from eggs Ascaris of Fidjeland ammonia, of effect reducing pathogen the Toevaluate Case andtheSafe Study Sludge 5.4:Sanitisation ofAscaris project by ammonia–die-off ., 1998; Pescon and Nelson, 2005). The principle of pathogen reduction with ammonia with reduction pathogen of principle The 2005). Nelson, and Pescon 1998; al., et 3 ) has been reported for several types of microorganisms, bacteria, viruses and parasites parasites and viruses bacteria, microorganisms, of types several for reported been has ) 4 + ad s cagd o dsub te ucinn o ognss Pr ad Diez- and (Park organisms of functioning the disturbs ion charged a as and ) 3 ) enters cells, takes up intracellular protons for the formation formation the for protons intracellular up takes cells, enters ) . (2013) monitored the viability the (2013) monitored al . et 113

Technology Technology and the odors produced. Indirect thermal dryers produce less contaminated vapor. vapor. produce lesscontaminated dryers produced.thermal Indirect odors and the Gas can requirements treatment be an issue depending on environmental dryer. out of the transported and collected be to needs water evaporated the by produced vapor the cases, both In carrier. heat the sludge, sludge need which fromcome the the operational reduces to in with separate the direct contact the heat convection to the sludge. In this case, the heat media carrying is often steam or oil, and does not allows which exchangerused, heat is a driers, thermal indirect In it. with transported are or it, through water in high pass they as sludge, is dewatered the mixed are with hot gases or air the that driers, thermal direct In content. sludge for used if dewatering preliminary require systems These 2007). al., et Direct are or also dryers to indirect referred as thermal convection respectively or dryers, (Lowecontact ortransport. allowing easierstorage form and inagranular stable are endproducts The heat. with water up evaporating of ability the taken on of based all exist, types been technologies Several has industry). paper technology (e.g. industries the other in and application original years, its from many improved and for sludge wastewater of management the in applied been has It 3). Chapter (see FS from liquids of types all of removal the allows drying Thermal andpelletising Thermal drying 5.5.4 114 alkalinising agent (calciumhydroxide) agent alkalinising produce ammonia. to two a time stages: 4-hour and forto contact faeces hydrolyseurine urea, followed by addition the of an urease requires processThe disinfection Sludge Safe added. the result, a As 9. around be of pH a above active not is to enzyme needs urea synthetic no and faeces containing pathogen the and ammonia between time contact the facilitates it as sludge UDDT FS. for most effective more than be to volumes appears smaller process This with drier much is sludge UDDT urine. in present ammonia naturally is the that with (UDDTs) toilets dry diverting urine from FS of reduction pathogen the achieve 2011May to from 2013.out Maywas until goal The carried was Sludge” “Safe called project Another iue57 TheSafe Sludge stage two disinfection process: hydrolysis ofurea catalysed by ureaseFigure5.7 (upto 4hrs) susana.org (2013). (estimateddisinfectant desinfection time:to hours Figure weeks). adapted from http://forum. and lime addition to increase pH and soachieve ammonium conversion into ammonia, aknown matter F Urine aecal 4 hours Stage 1 Urea Urease Ammonium NH 4 + Ca(OH) Lime 2 Hours toweeks Disinfectant Stage 2 Ammonia NH 3 Case studies 5.5 and 5.6 present examples with FS to produce asoilconditionerandfertiliser. FSto Case studies examples with 5.5and5.6present market. to and transport to easy relatively are conditioner,and soil or source energy an as used be can then pellets dried The technologies. drying thermal and dewatering mechanical combines Pelletising requirements. highmaintenance andthe system, in the dust and gas fi of the to due risks explosion potential or re the requirements, energy high expense, the are 10). Chapter (see constraints main The agriculture in used market,be can to and and handle to easy results in drying Thermal a significant reduction in volume as well sludge as content. is Dried pathogen Potential advantages ofthermaldrying andconstraints (Adapted from(Adapted Nikiema Case Study 5.5:Pellets as soilconditioner/fertiliser to pasteurise it to an 80 – 90 % solid product. The pellets can be sold and used as a fuel or as a soil a as or fuel a as used and sold amendment. be can pellets The product. solid % 90 – 80 an to it pasteurise to and solids % 35 – 20 between sludge any treat to container) one (in form modular in available now is LaDePa the modifi redesigns several and cations After consumes. plant treatment wastewater sludge conventionalactivated a what of half approximately is equivalent consumptionperson per energy the intensive, energy is this Although radiators. infrared wave medium of bymeans pathogen achieved is reduction and dryer”), “Parsep so-called (the 100°C at air a with on dried pellets are pellets deposit These which belt. moving screws via sludge dewatered from detritus separates mechanical It and steps. thermal treatment subsequent of number a over latrines pit from FS treat can that developed and Dehydration (Latrine in Systems. Separation Here, conjunction technology a Particle their partner with technology has been LaDePa Africa) the South Durban, (EWS, is Sanitation and Water eThekwini pelletising by developed system and Pasteurisation) drying combining of example Another Case Study 5.6:Pelletising LaDePamachine from Durban,South Africa best pellets. the obtain to sludge for dried isrecommended additionto mixture 3% a stirring; manual under starch the dry to 5˚C) ± (85 water hot of addition the through starch the Nikiema candidate. better the be proved to starch cassava which From preliminary investigations cassava starch and clay were identified as possible binding materials, of ofpellets. andstability length andthe were generated, quality pellets that high- of amount the were 0-10%- parameters Output mass). (clayin starch or concentration and type binder and mass) identifiin (10-55%were content moisture parameters ed: operating key of number 380V a 1:2 a of in co-compostedand bed (Nikiema unplantedan drying in sludge stabilised and dewatered ratio tank version septic with mixed (a was sludge latrine machinery public FS, dried of constructed source a As locally pelletiser). using pelletised subsequently products, of were types fi different produce vewhich to FS dried with out carried were experiments Ghana, In et al et ., 2013) . (2013) al. et pre-treating recommend ., 2013). al., et A 115

Technology Technology eg vniain ar iig tmeaue. h mi fcos n ecn te vprto effi ciency evaporation infl the uencing factors main The temperature). greenhouses mixing, the air in conditions ventilation, the (e.g. control to devices with operation, continuous or batch for exist Options days. 20 to 10 about for processed and basins these into disposed is Sludge walls. and basins concrete covers, transparent with structures greenhouse in constructed generally is technology This the nineteenth century in Europe and USA for the treatment of sludge wastewater (Hill and Bux, 2011). They also have is applied been in used solar on sludge of driers. a scale A drying large since special form Solar drying 5.5.5 drawbacks. other are maintenance forknowledge required specialised and costs, capital use, power.energy The electrical on dependency the is pelletisiing and drying mechanical of constraint main the Moreover, requirements high. knowledgebe may skilled and costs system, the of breakdown a of case in However, content. for safe therefore and pathogens from free use. agricultural Pellets can are also be used pellets as a dry the fuel in industrial used, combustion, regardless of are the pathogen processes which on Moreover, depending robust. and mobile compact, are they that are technologies these of advantages main The Potential andpelletising advantages ofsludge andconstraints drying 116 municipal solid waste (see also Chapter 2, Section 2.9.7), which complicates treatment and the the and treatment complicates which 2.9.7), Section detritus. remove isableto the LaDePa ofausefulproduct, butthe rendering 2, Chapter also (see waste solid municipal non-organic of amount high a quite contains sludge latrine Commonly,pit pre-sorting. (manual) any without sludge latrine pit treat to designed is that is machine LaDePa the of signifi A advantage cant Schematic representation oftheLaDePamachine. Figure 5.8 separators detritus rotation feed sludge porous steelbelt from generatormotor pre-drying chamber using exhaustheat hot airinlet pasteurisation chamber using medium-wave moist airextraction infrared radiators pasteurised sludge Final dried solid content of about 40% (after 12 days drying) up to about 90% (after 20 days drying) al.(2010) conditionsbydrying) Shanahanet were found underdifferent andHillBux(2011)days 20 respectively. (after 90% about to up drying) days 12 (after 40% about of content solid dried Final (Shanahan UV to sensitive very are that coliforms faecal for especially reduced, slightly effi reduction pathogen is ciency the Therefore, cover. the by blocked is UV as such light wavelengths Short 2005). inflBux, also and mixing (Seginer air dry process and sludge the initial uencing the of content with solid rate, ventilation the and temperature air the variation, solar the are systems these in t Z rsne i Catr 7 r dsge t ad n hs eeto. n diin Bx . provides 5.1 Box addition, In selection. this in onhow compare aid to options. costs technology information oftreatment to designed are 17 Chapter in presented Z from to Planning FSM A and Scheme Selection Technology The experience. operating long-term of lack the by complicated is which considered, be to have factors many treatments, of combinations and/or This chapter has provided an overview of treatment technologies. When selecting the optimal treatment TREATMENT SELECTING TECHNOLOGIES 5.6 purpose. for beconsidered this needto that parameters and operating design on or low-incomecountries in FS of treatment the for technology this of use the on available is to ventilate the Although greenhouses. pilot tests are being out, carried for the moment no information main effi The of ciency. dewatering complexity potential limited high space requirements need are constraints the and for sludge, the as mechanical the means well to turn as the the and requirements, costs, energy investment low low and the technology are the option this of advantages main The Potential advantages ofsolardrying andconstraints other. the to of costs from one context but in meantime the reasonable estimates have to be calculated. diffiAnother culty is heterogeneity the which to base estimates on. Access to cost this will data improve overtime increased with installations, on experience operating long-term no is there and scale, pilot or laboratory the at operational mostly are they that are chapter, this in presented technologies FSM of costs diffi The the comparing of culty FSTP. the andmaintain operate to stakeholders the of capacity the and planned, fibeen have the enforce that to mechanisms nancial stakeholders the of capacity the on depends largely plan FSM a of cost success 17.5). the and Section Ultimately, (see coverage recovery broad satisfaction, household ensures which that but cheapest, the always not is option best The long-term. the over paid be will it how and whom by but important, is that cost the expenditures all recurrent (e.g. O&M, transport, capacity-buildingincluding and policy project, development). It is notthe only of horizon planning the over i.e. basis, life-cycle a on compared be to need Planning, as coststhe of Technology are directly and interrelated impacted by Costsother these factors. and Management includes that approach integrated an of outside made be cannot comparison cost A explains models different of financial fl ows, and Chapter 12 explains models different of management. 1317.1).Chapter (Table addition, Z In to A 17.10)from Planning (Figure FSM Scheme and Selection process, and Chapter 17 Planning Integrated FSM Systems summarises all of the steps in the decision-making Technology the during taken be to need that steps the of all are Section Planning the in Outlined Linda Strande Box options oftreatment comparison 5.1:Cost technology ., 2010). al., et 117

Technology Technology 118 2 Equivalent Equivalent Annual Cost (EAC): this calculation entails determining the required capital investment, 2 investment, capital required the determining entails calculation this (NPV): Value Present Net 1 lifetime: expected costs over calculate two to are There the ways AC Where: Equation 5.3: C the costs will be borne (e.g. household, government, private sector). private (e.g.household,government, costs willbeborne the whom by evaluate to critical is it estimated, are chain service entire the for costs When considered. be to needs chain service Toentire Senegal. the comparesystems, based Dakar sewer in and FSM systems Dodane by provided is (2012) in and Tablesummarised borne 5.2. The analysis was done based on existing are side-by-side operational costs the how and systems, based sewer and FSM complete of comparison A leachate. and sludge treated of enduse or transport, and collection level, household the at system containment onsite the not and bed, drying the of cost the included only estimate This pilot. the during on operation based forecasted be could but notincluded, were removal) sludge plants, harvesting (e.g. maintenance and operations Ongoing solids). total of ton per USD 186 or capita per be USD (0.95 to USD/year 1,500 estimated were costs annualised phase, pilot the during operation and construction on Based in Thailand bed conducted byresearch Koottatep drying on planted solids estimatingof example pilotAn costsa on providedbased is scale bytreated. Steiner total of tons to costs the normalise to is systems among comparisons for possibility Another n F rate interest i =real o o o = annual operating cost of faecal sludge management system component system management sludge (USD/capita/year) cost offaecal =annualoperating = service lifetime of sanitation system (years) system lifetime ofsanitation =service = capital cost of sanitation system component system (USD/capita) cost ofsanitation =capital o lifetime with interest rate, in addition to annual operations and maintenance costs as shown in shown as equation 5.3: costs maintenance and operations annual to addition in rate, interest with lifetime lifetimes. different Annual with costs are calculated as annualised cost the capital over expected the be can technologies among NPV comparisons for used The be can EAC but lifetime. versa, vice and expected EAC, an into converted the over basis yearly a on required be would that money of amount the to converted then is flamount cash This future lifetime. all expected and the over ows lifetimes. equivalent options with lifetime. the The lower sum, less the the expensive option the is. This can value be used to compare would be invested need to amount of money that today cover to i.e. the during all expenses worth, present the to converted then is amount This fllifetime. cash expected future all the and over ows = annualised cost of sanitation system component system (USD/capita/year) =annualisedcost ofsanitation AC o =-C o [] (1+ i) (1+ i) n n o o

- 1 . - i F o . (2001) and Surinkul (2002). al. (2001)et and Surinkul . (2002) based (2002) al. et et al . et 6 5 4 3 2 1 of each city(seeSection14.4.8).of each m more affordable than conventional dual-pipe water delivery and sewer systems at fl ows than 100greater is reclamation including treatment wastewater decentralised Japan in example, For found. be can point breakeven a typically and linear, not is cost and scale between correlation The decision. a making when chain supply whole the consider to important is it reason, this For reduced. be travel can time as and affordable distances more are plants decentralised smaller that appears it account, into taken is sludge of haulage when However, plants. smaller than effective cost more of being economy plants larger the in basis, results cost scale capital and management a On 2009). (Maurer, needed as basis modular a in built be can long- they flas more meeting exible are technologies of decentralised requirements, terms growth urban In term systems. more sewer-based be centralised to than tend technologies semi-centralised FSM or decentralisation. decentralised or centralisation of level the as such factors by complicated also is technologies treatment of comparison the 14.5.3, Chapter in discussed be will As al . Comparison ofFSM andsewer based systemsoperational onexisting side-by-side systems inDakar, Table5.2 Valorisation End-products (operating) = biogas, reclaimed water, biosolids water, reclaimed =biogas, End-products Valorisation (operating) consumption basedonwater resident paidby every tax =sanitation Tax (operating) Sanitation transport =sewer, emptying onsite CollectionConveyance pumping (operating) truck fee, stations, plant treatment sludge plant,faecal treatment =wastewater andoperating) Plant(capital Treatment trucks =sewer, vacuum pumping CollectionConveyance (capital) stations, =householdsewerconnection,septic tank HouseholdConnection (capital) TOTAL Endproducts Valorisation Treatment Plant Sanitation Tax TOTAL Treatment Plant Conveyance Collection Conveyance Collection TOTAL Connection Household 3 /day (Gaulke, 2006). All of these factors are very dependent on the local context and the specifi and the local context dependent on the very are /day factors (Gaulke, 2006). All of these cities Senegal (DodaneSenegal et al.,2012) 1 CAPITAL ANDANNUALCAPITAL OPERATING COSTS COMBINED (PERCAPITA*YEAR) 4 2 6 5 3 3 -2.00 0.00 0.00 -2.00 0.00 0.00 0.00 0.00 0.00 -2.00 House House ANNUALISED COSTS (PERCAPITA*YEAR) CAPITAL ANNUAL OPERATING COSTS (PERCAPITA*YEAR) SEWER BASED (SB) BASED SEWER SEWER BASED (SB) BASED SEWER -9.97 1.13 -6.46 2.00 -6.64 -42.66 -7.49 -30.20 -4.98 -52.63 ONAS ONAS Enduser Enduser -0.01 -0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -0.01 TOTAL TOTAL -11.98 -42.66 -54.64 -7.00 0.00 0.00 -2.00 -5.00 -2.74 0.00 0.00 -2.74 -9.74 House House FAECAL SLUDGEMANAGEMENT (FSM) FAECAL SLUDGEMANAGEMENT (FSM) 0.26 0.00 0.00 0.00 0.26 -0.28 0.00 -0.28 0.00 -0.02 C&T C&T -0.83 0.01 -0.84 0.00 0.00 -1.03 -1.03 0.00 0.00 -1.86 ONAS ONAS Enduser Enduser -0.01 -0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -0.01 TOTAL TOTAL -7.58 -4.04 -11.63 119

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