Concept and Experiences of wastewater Concept and Experiences of wastewater treatmenttreatment

In Cakung SlaughterhouseIn Cakung SlaughterhousePD Dharma JayaPD Dharma Jaya

PUSAT PENGKAJIAN DAN PENERAPAN TEKNOLOGI LINGKUNGAN

Badan Pengkajian dan Penerapan Teknologi

UTEC

The main functional areasThe main functional areas of Cakung Slaughterhouse of Cakung Slaughterhouse

      Stabling of cattle       Slaughtering in main slaughterhouse       Slaughtering in traditional slaughterhouse       Power supply, workshop       Administration       Sanitary facilities

Concept of the Wastewater treatmentConcept 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

Table 1. The most important equipment of the WWTP

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 m³Eff.-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

The main requirementsThe 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

ActualActual condition of wastewatercondition of wastewater

Total amount of wastewater 100 – 200 m3 /day COD total 6000 – 8000 mg/l COD dissolved 1600 - 2200 mg/l

Inflow WWTPCOD 7.747 mgO2/l

100%

Step screen 386 mg/l5.1 %

Screenings

Fine screen 526 mg/l7.1 %

Screenings

Mixing /Storage tank

600 mg/l8.8 %

Loses of dissolved COD by anaerobic process in this tank

Pre-sedimentation

3.666 mg/l49.1 %

Sludge

AnaerobicFixed BedDigester

1.384 mg/l18.5 %

Biogas

Final sedimentation

39 mg/l0.5 %

Sludge

Effluent WWTPCOD 813 mgO2/l

10.9%

Total efficiency89.1%

Figure 5. Mass balance and efficiency of component

Fixed Bed Digester PerformanceFixed Bed Digester Performance

Amount of wastewater: 353 m³/d Gas production: 220 m³/d Methane content: 75 % Amount of sludge: 5 m³/d

Figure 6. Feeding rate of digester during start up period

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Figure 7. Biogas production of digester during start up period

Calculation of current production: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

RESUMERESUME I 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.

RESUMERESUME II 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.

RESUMERESUME III 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.