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Concept and Experiences of wastewater treatment In Cakung Slaughterhouse PD Dharma Jaya. PUSAT PENGKAJIAN DAN PENERAPAN TEKNOLOGI LINGKUNGAN Badan Pengkajian dan Penerapan Teknologi UTEC. The main functional areas of Cakung Slaughterhouse. ü Stabling of cattle
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Concept and Experiences of wastewater treatmentIn Cakung SlaughterhousePD Dharma Jaya PUSAT PENGKAJIAN DAN PENERAPAN TEKNOLOGI LINGKUNGAN Badan Pengkajian dan Penerapan Teknologi UTEC
The main functional areas of Cakung Slaughterhouse • üStabling of cattle • üSlaughtering in main slaughterhouse • üSlaughtering in traditional slaughterhouse • üPower supply, workshop • üAdministration • üSanitary facilities
Concept of the Wastewater treatment • ·Low running costs, means low demand for manpower, • energy and chemicals, even if the investment cost might • be higher • ·Simple and clear operation procedure to simplify the work • for operators and minimize the risk of miss management • ·Minimization of sludge production and demand of sludge • handling • ·Utilization of renewable energy and nutrients • Energy production in form of biogas and current production as • benefit • Utilization of sludge in composting process
Figure 3. The system plan for waste and wastewater treatment process
Position Fabricate Type size Step screen McCoy Step screen Fine screen Haase Static screen Mixing/storage tank Tirtakreasi Concrete basin 200 m³ Pre-sedimentation Tirtakreasi Concrete basin 40 m³ Fixed bed digester Tirtakreasi Concrete tank with support material Tot-Vol.: 590 m³ Eff.-Vol.: 400 m³ Final sedimentation Tirtakreasi Steel tank 50 m³ Gas holder Muche Plastic bag in container 20 m³ Genset Dimag Net-parallel 45 kW Table 1. The most important equipment of the WWTP
The main requirements • Step screen eliminates suspended solids >3 mm particle size • Fine screen separates suspended solids >1mm particle size • Pre-sedimentation eliminates >90 % of suspended solids • Fixed bed digester degrades >70 % of dissolved COD • Over all efficiency of WWTP > 80 % of COD-total
Actualcondition of wastewater • Total amount of wastewater 100 – 200 m3 /day • COD total 6000 – 8000 mg/l • COD dissolved 1600 - 2200 mg/l
Inflow WWTP COD 7.747 mgO2/l 100% Step screen 386 mg/l 5.1 % Screenings Fine screen 526 mg/l 7.1 % Screenings Mixing / Storage tank 600 mg/l 8.8 % Loses of dissolved COD by anaerobic process in this tank Pre-sedimentation 3.666 mg/l 49.1 % Sludge Anaerobic Fixed Bed Digester 1.384 mg/l 18.5 % Biogas Final sedimentation 39 mg/l 0.5 % Sludge Effluent WWTP COD 813 mgO2/l 10.9% Total efficiency 89.1% Figure 5. Mass balance and efficiency of component
Fixed Bed Digester Performance • Amount of wastewater: 353 m³/d • Gas production: 220 m³/d • Methane content: 75 % • Amount of sludge: 5 m³/d
Figure 7. Biogas production of digester during start up period
Calculation of current production: • Power output: 35 kW • Gas uptake: 15.6 m³/h • Gas production: 220 m³/d • Current production: 495 kWh/d
Balance of demand and production: • Demand: 122 kWh • Production: 495 kWh • Surplus: 373 kWh • Benefit: • The benefit from electrical generation by Biogas is: • Current tariff (December 2002): 578.00 Rp/kWh • Surplus current: 373 kWh • Benefit: 215,541 Rp/d • 6,466,218 Rp/month
RESUME I • The presented system is very suitable to treat the wastewater from slaughterhouse and stable area. • - All components of the plant are dimensioned by hydraulic load and flow rates. Therefore it is in general very important to minimize the amount of waste- water to reduce the size/capacity of equipment and investment costs.
RESUME II • - The volume of the storage and mixing tank might be chosen smaller, because the fixed bed digester is able to handle discontinuous flow, furthermore it was found out that a part of dissolved COD is already degraded during the storage time. The consequence is a lower production of biogas. • - The digester is dimensioned for minimum hydraulic retention time of 3 days. It might be possible to reduce the minimum retention time to less than 2 days. High load tests showed that the digester is very flexible and is able to handle shock loads.
RESUME III • - The final sedimentation eliminates only 0,5 % of pollution, but is an expensive component. It might be suitable to drive a system without final sedimentation. • - In general very important to increase the amount of slaughtering of cattle to increase the performance of wastewater treatment plant.