Presentation on theme: "UNIVERSITY OF NAIROBI ENVIRONMENTAL & BIOSYSTEMS ENGINEERING"— Presentation transcript:
1UNIVERSITY OF NAIROBIENVIRONMENTAL & BIOSYSTEMS ENGINEERINGDesign of a biological slaughterhouse wastewater treatment system (Using an anaerobic baffle reactor – constructed wetland system) < case study of Kiserian Slaughterhouse>Mwangi Simon ThukuF21/2492/2009Supervisors : Mr. Orodi OdhiamboEng. D. A. Mutuli
2BACKGROUNDApproximated slaughterhouse waste content and NEMA standards for disposal into the environmentWaste ContentSlaughterhouse(approx.)NEMA Disposal StandardsBOD 5days at 20 oC1000 – 4000 mg/L30 mg/lCOD2000 – mg/L50 mg/lOil and greaseHighNilTotal Suspended Solids200 – 1500 mg/LTotal Nitrogen100mg/lJohns et al., 1995; Manjunath et al., 2000, NEMA
4Problem StatementThis waste water flows to R. Kiserian and eventually gets to Kiserian Dam.This causes eutrophication and anoxia in the water bodies.Waste from slaughterhouses also leads to air and soil pollutionPre- treated Wastewater getting into the streamsParameterpHTSS, mg/lTDS, mg/lCOD, mg/lBOD5mg/lNH4+N (N)mg/lContent7.7530703262.5936.25141.5
5Site Analysis Kiserian is a settlement in Kajiado county Habitants are mainly pastoralist communityWarm and Temperate climate.Rainfall =833mmTemperature = 17.8
6To analyze the amount and the content of wastewater ObjectivesOverall objectiveTo design a biological slaughterhouse wastewater treatment system Specific ObjectivesTo analyze the amount and the content of wastewaterTo establish pertinent parameters for design of a biological slaughterhouse waste water treatment system.To use the parameters from (ii) to size the baffle reactor and the constructed wetland.
7Statement of the scope Literature review Survey work Carrying out testsDetermination of System Design ParametersMaking detailed engineering drawingsLiterature reviewTreatment Process ( primary, secondary and tertiary treatment)Why anaerobic?Anaerobic Baffle reactor (improved septic tank)Constructed Wetland
8Methodology Survey Soil and waste water sampling Laboratory tests (soil & waste water)Determining the efficiency of ABRABR volume determinationResult analysisDesigning the wetlandStructural design of the ABR
9Theoretical Framework Chemical oxygen demand,Biochemical Oxygen Demand, BOD5,mg/L =Design Criteria for anAnaerobic baffle reactorHydraulic Retention time, HRT>24 hours at maximum sludge depth and scum accumulationSludge Accumulation Rate, SARDepending on TSS removal rate and waste water flowSludge and Scum Accumulation VolumeSludge Accumulation Rate multiplied by flow rateDesludging interval>1 yearNumber of upflow chamber, N>2Maximum upflow velocity, v1.4 – 2m/hSasse (1998), Wanasen (2003), Foxon et al., (2004) etc
10Results Parameter (ABR)m Formula Results Flow rate, Q (200 x C) + ( 100 x S)14.5m3/dayLength of upflow chamber, Lc=< half depth1mMaximum Peak Upflow Velocity, VpQ/t2.4167m3/hArea of upflow chamber, AuVp/v1.343m2Width of the chamber, CwCw/Lc1.343m2 ≈2mActual upflow velocity, VaVp/(Lc x Cw)1.208 m/hActual working volume, VCw x d x (Lc+ Ld)N30 m3Hydraulic Retention Time, HRTV/Q2 daysBOD removalBODeff = BODin e- Kt x Tmg/lOrganic Loading Rate(CODin x Q)/ V1.314 kg COD/m3.d
11Results Cont’d Parameter Value Results BOD5 removal, percent 80 to 90% 93.625mg/lCOD removal , mass1.6 x BOD5, removal1348.2mg/lBiogas production0.5m3/kg COD removed9.77 m3Methane production0.35m3/kg COD removed6.84m3Leslie C.P. et al, 1999
12Results Cont’d Parameter (CW) Formulae Water Budget Qe = Qi + (P – ET) AsSurface Area of the system, AsAs = (Qave(ln Co – ln Ce))/Kt x d x nAspect Ratiobetween 2:1 to 3:1 (Mitsch et.al 2007)Retention Time ,t(Lwyn)/Q (Crites et.al, 2006)Bed Slope0.5% to 1%Qi = 14.5m3/dy = 0.7 mm2As =t = 1.85 dayswidth = 7.94 mdh = 0.01 x 15 = 0.15mLength = 2 x 9 = 16 mslope is taken to be 1.5
18Conclusion Objectives of the design project were met. slaughterhouse wastewater was observed to have high content of waste.The BOD5 removal efficiency for the ABR was found to be 90% (i.e. from mg/l to mg/l) with a HRT of 2.38days. The organic lading in the ABR was found to be kg COD/m3.d (should range between 1 – 3 kg COD/m3.d).The CW reduced the concentration of nitrates in the waste water from mg/l to 100 mg/l and the BOD from mg/l to 15.62mg/l.System was found to have a 98.4% BOD reduction
19RecommendationsThe first compartment of the ABR should be modified and increased in size to trap as much solids as possible.The ABR should be made air tight and a system to improve/increase the pressure of the biogas in the reactor to allow gas collection otherwise the first compartment can be constructed in such a way that it has a gas holder and made airtight (shape of a fixed dome).A gradient should be created between the ABR and the CW so as to utilize gravity as the driving force.Wastewater monitoring/ testing should be done on a regular basis in order to ensure that the content of waste flowing to the stream conforms with the NEMA standards and as a way of monitoring the performance of the system.
20ReferencesMuench, E. (2008): Overview of anaerobic treatment options for sustainable sanitation systems. In: BGR Symposium "Coupling Sustainable Sanitation and Groundwater Protection".Bachmann, A., Beard, VL. and McCarty, PL. (1985). Performance Characteristics of the Anaerobic Baffled Reactor. Water Research 19 (1): 99–106.Sergio S. Domingos (2011), Thesis on Vertical flow constructed wetlands for the treatment of inorganic industrial wastewater, Murdoch University WA, Australia.Morel A. and Diener S. (2006). Greywater Management in Low and Middle-Income Countries, Review of diff erent treatment systems for households or neighbourhoods. Swiss Federal Institute of Aquatic Science and Technology (Eawag). Dubendorf, Switzerland.Nijaguna B.T. (2002), Biogas Technology, New Age International (P) Limited, New Delhi.
21ReferencesRustige H &Platzer Chr. (2000),Nutrient Removal in Subsurface Flow Constructed Wetlands for Application in sensitive Regions in: Proceedings – 7th Int. Conf. On Wetland Systems for Water Pollution Control, Orlando, USALeslie Grady .C, Glen .T, (1999), Biological Wastewater treatment, 2nd ed, Maral Dekker ,Inc, New YorkFoxon KM, Pillay S, Lalbahadur T, Rodda N, Holder F, Buckley CA (2004) The anaerobic baffled reactor(ABR): An appropriate technology for on-site sanitation. Water South Africa 30,Lawrence A.W. and McCarty p.L (1970): Unified basis for biological Treatment Design and Operation. J. Sanit. Eng. Div., Am. Soc. CivEngrs.Walter R.H., Shermah R.M. and Downing D.L. (1974): Reduction in Oxygen demand of abattoir effluent by Precipitation with metal. J. Agric. Fd Chem