TREATMENT OF A DAIRY FARM WASTEWATER USING A PILOT SCALE UPFLOW ANAEROBIC SLUDGE BLANKET (UASB) PROCESS By Ashveen Deerpaul & Arvinda Kumar RAGEN

PRESENTATION PLAN Introduction Aim & Objectives Methodology Results & Discussions Conclusions

INTRODUCTION Dairy Farming in Mauritius Water consumption in a dairy farm 175 L per cow per day Water usage in a dairy farm: Direct water usage Indirect water usage

INTRODUCTION Dairy Farm Wastewater Organic Matter Pathogens Suspended Solids Nutrients

AIM & OBJECTIVES Aim: Assess the performance of a Pilot Scale UASB reactor during the treatment of dairy farm wastewater Objectives: Characterize the dairy farm wastewater. Characterize the influent and effluent in terms of COD, VFA, TSS, pH. Evaluate the performance of the UASB reactor at varying HRT. Characterize the biogas produced. Perform a preliminary design of an industrial scale UASB reactor for a local dairy farm.

METHODOLOGY Collection of dairy farm wastewater Pre-treatment of the wastewater Set-up of UASB reactor Sampling Protocol Analytical Method

METHODOLOGY Collection of raw wastewater

METHODOLOGY Experimental Set up

METHODOLOGY Set up of UASB reactor

METHODOLOGY Pre-treatment of wastewater

METHODOLOGY Operating conditions WeekFlow rate (L/h) HRT (hours) OLR (KgCOD/m 3.d) Upflow velocity (m/h) 1, 2,

Sampling Protocol StreamSampling Type Raw WastewaterComposite Reactor InfluentGrab Reactor EffluentGrab SludgeGrab METHODOLOGY

Analytical Parameters The raw wastewater was analyzed for COD, pH, TSS, nutrients, TKN and Total Coliform. The UASB influent and effluent were sampled and analyzed for COD, VFA, pH, Temperature and TSS The Sludge was analyzed for VSS, TSS, SV and Sludge Activity Test (SAT) METHODOLOGY

RESULTS & DISCUSSIONS ParameterRangeMean pH Temperature,  C COD, mg/L TSS, mg/L TKN, mg/L NH 3 – N, mg/L PO 4 2-, mg/L Total Coliforms, CFU/100ml 7.8 – – – – – – –  Characteristics of raw wastewater

RESULTS & DISCUSSIONS Characteristics of Sludge ParameterConcentration pH Temperature,  C TSS, mg/l VSS, mg/l SAT, gCOD rem /gVSS.d

RESULTS & DISCUSSIONS ParameterRangeMean pH Temperature,  C COD t, mg/l COD s, mg/l TSS, mg/l VFA, mg/l VFA/COD 6.7 – – – – – – – Characteristics of Influent

RESULTS & DISCUSSIONS Appearance of UASB Effluent

RESULTS & DISCUSSIONS Characteristics of effluent ParameterRangeMean pH CODt, mg/l CODs, mg/l VFA, mg/l TSS, mg/l 7.2 – – – – –

RESULTS & DISCUSSIONS Effluent COD profile

RESULTS & DISCUSSIONS Performance of UASB reactor (% COD removal efficiency) Average COD removal efficiency = 78.7%

RESULTS & DISCUSSIONS Performance of UASB reactor (% VFA conversion) Average VFA converted = 72.9%

Performance of UASB reactor at varying HRT RESULTS & DISCUSSIONS

Biogas production

PRELIMINARY DESIGN Volume of EQ tank30 m 3 Height of tank4300 mm Diameter of tank - at bottom - at center 3000 mm 3200 mm Thickness - at bottom - on top 25 mm 12 mm Construction materialFibre glass Equalization Tank

PRELIMINARY DESIGN Volume of reactor Height of reactor 40 m mm Diameter of reactor3600 mm Thickness of wall200 mm Material of construction Height of the GLS separator No. of gas dome Base diameter of dome Top diameter of dome (W t ) Depth from top of the dome,  h Height of inclined wall of dome, h Length of inclined wall of dome Width of the water surface (Ws) Reinforced concrete 1330 mm mm 500 mm 200 mm 1350 mm 1760 mm 2900 mm UASB reactor

PRELIMINARY DESIGN

wastewater Screen Holding tankEQ tank NaOH UASB reactor Final effluent Biogas Effluent Tank

PRELIMINARY COSTING Summary of costsCost (Rs) Equipment costs: UASB reactor Equalisation tank Centrifugal pump NaOH Dosing pump Agitator Total purchased equipment cost 455, ,850 28,850 27,200 48, ,606 Total Direct costs 1,547,042 Total Indirect costs 739,891 Total Fixed Capital Investment 2,286,933 Working Capital 403,576 TOTAL CAPITAL INVESTMENT TOTAL ANNUAL COST 2,690, ,000

CONCLUSIONS COD removal efficiencies: 78.7% VFA conversion: 72.9% TSS removal efficiencies: 94.2% Optimum HRT of 8 hrs Maximum gas production: 8.89 L/d In light of this study, it can be concluded that the UASB process is appropriate for the treatment of wastewater generated by a local dairy farm.

Adopt a tertiary treatment using a Horizontal Subsurface Constructed Wetland Use of the biogas emanating from the UASB reactor: Cooking purposes Produce electricity Alternative fuel RECOMMENDATIONS

Energy recovery potential from the biogas produced from the UASB reactor. Effect of VFA toxicity and shock loads on the methanogenic sludge can be investigated. Variation of methanogenic activity along the height of the UASB reactor. Image characterization of the sludge. Possibility of integrated farming using the treated effluent. FUTURE WORKS

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