Presentation on theme: "D ESIGN OF A BIOLOGICAL SLAUGHTERHOUSE WASTEWATER TREATMENT SYSTEM (U SING AN ANAEROBIC BAFFLE REACTOR – CONSTRUCTED WETLAND SYSTEM ) Mwangi Simon Thuku."— Presentation transcript:
D ESIGN OF A BIOLOGICAL SLAUGHTERHOUSE WASTEWATER TREATMENT SYSTEM (U SING AN ANAEROBIC BAFFLE REACTOR – CONSTRUCTED WETLAND SYSTEM ) Mwangi Simon Thuku F21/2492/2009 Supervisors : Mr. Orodi Odhiambo Eng. D. A. Mutuli UNIVERSITY OF NAIROBI ENVIRONMENTAL & BIOSYSTEMS ENGINEERING
BACKGROUND Approximated slaughterhouse waste content and NEMA standards for disposal into the environment Waste Content Slaughterhouse (approx.) NEMA Disposal Standards BOD 5days at 20 o C 1000 – 4000 mg/L 30 mg/l COD 2000 – mg/L 50 mg/l Oil and grease High Nil Total Suspended Solids 200 – 1500 mg/L 30 mg/l Total Nitrogen100mg/l Johns et al., 1995; Manjunath et al., 2000, NEMA
P ROBLEM S TATEMENT This 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 pollution ParameterpHTSS, mg/lTDS, mg/lCOD, mg/lBOD 5 mg/lNH 4 + N (N)mg/l Content Pre- treated Wastewater getting into the streams
Kiserian is a settlement in Kajiado county Habitants are mainly pastoralist community Warm and Temperate climate. Rainfall =833mm Temperature = 17.8 Site Analysis
O BJECTIVES Overall objective To design a biological slaughterhouse wastewater treatment system Specific Objectives i. To analyze the amount and the content of wastewater ii. To establish pertinent parameters for design of a biological slaughterhouse waste water treatment system. iii. To use the parameters from (ii) to size the baffle reactor and the constructed wetland.
S TATEMENT OF THE SCOPE Survey work Carrying out tests Determination of System Design Parameters Making detailed engineering drawings Literature review Treatment Process ( primary, secondary and tertiary treatment) Why anaerobic? Anaerobic Baffle reactor (improved septic tank) Constructed Wetland
Methodology Soil and waste water sampling Laboratory tests (soil & waste water) Survey ABR volume determination Result analysis Determining the efficiency of ABR Structural design of the ABR Designing the wetland
Theoretical Framework Chemical oxygen demand, Biochemical Oxygen Demand, BOD 5,mg/L = Design Criteria for anAnaerobic baffle reactor Hydraulic Retention time, HRT>24 hours at maximum sludge depth and scum accumulation Sludge Accumulation Rate, SARDepending on TSS removal rate and waste water flow Sludge and Scum Accumulation Volume Sludge Accumulation Rate multiplied by flow rate Desludging interval>1 year Number of upflow chamber, N>2 Maximum upflow velocity, v1.4 – 2m/h Sasse (1998), Wanasen (2003), Foxon et al., (2004) etc
Results Parameter (ABR)mFormulaResults Flow rate, Q(200 x C) + ( 100 x S) 14.5m 3 /day Length of upflow chamber, Lc =< half depth 1m Maximum Peak Upflow Velocity, Vp Q/t m 3 /h Area of upflow chamber, AuVp/v 1.343m 2 Width of the chamber, CwCw/Lc 1.343m 2 ≈2m Actual upflow velocity, VaVp/(Lc x Cw)1.208 m/h Actual working volume, VCw x d x (Lc+ Ld)N30 m 3 Hydraulic Retention Time, HRT V/Q2 days BOD removalBOD eff = BOD in e - K t x T mg/l Organic Loading Rate(CODin x Q)/ V1.314 kg COD/m 3.d
Results Cont’d ParameterValueResults BOD 5 removal, percent80 to 90%93.625mg/l COD removal, mass1.6 x BOD 5, removal mg/l Biogas production0.5m 3 /kg COD removed 9.77 m 3 Methane production0.35m 3 /kg COD removed 6.84m 3 Leslie C.P. et al, 1999
Results Cont’d Parameter (CW)Formulae Water BudgetQe = Qi + (P – ET) As Surface Area of the system, A s A s = (Qave(ln Co – ln Ce))/Kt x d x n Aspect 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 = 14.5m 3 /d A s = m 2 Length = 2 x 9 = 16 m width = 7.94 m y = 0.7 m t = 1.85 days dh = 0.01 x 15 = 0.15m slope is taken to be 1.5
Conclusion Objectives of the design project were met. slaughterhouse wastewater was observed to have high content of waste. The BOD 5 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/m 3.d (should range between 1 – 3 kg COD/m 3.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
Recommendations The 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.
References Muench, 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.
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