ANAEROBIC DIGESTION OF SLUDGE IN WASTEWATER TREATMENT PLANT FOR ENERGY RECOVERY – A CASE STUDY OF HANOI URBAN DISTRICT
Keywords:Anaerobic digestion, biogas, energy, sewerage sludge treatment, resource recovery.
In a wastewater treatment plant (WWTP) energy optimization is a big concern whilst sludge stabilization and energy recovery by anaerobic digestion implementation has recently gained importance. The calculation of an urban district level (selected as Long Bien) with 352,000 populations showed that with a total energy required of 39,750 kWh per day in WWTP, it could be supplied by utilization of biogas production, varying from 0% to ~ 43.44 % depending upon the non-application or application of anaerobic digestion for sludge treatment. In mesophylic anaerobic digestion, the biogas yields production of the calculated WWTP was obtained at 3,710 m3/day; equal to 8,394 kWh power and 13,919 kWh heat per day. As a conventional treatment process, centrifugal dewatering of sludge required an additional energy of 1,376 kWh per day for recycling, pumping, mixing as well as transporting sludge. The conclusion was that anaerobic digestion can reduce the green-house gases versus conventional dewatering. The results from this research can thus demonstrate the applicability of anaerobic digestion on conversion of waste to energy, looking forward to resource recovery.