| The objective of this research was to investigate the effects of primary treatment optimization on the energy balance of a municipal wastewater treatment process consisting of conventional activated sludge process and anaerobic digestion. For a case study facility (Oakville Southwest WWTP in Oakville, Ontario), using historical plant data in conjunction with sampling, bench scale settling and particle size analysis experiments, alternatives for primary treatment optimization were developed. BiowinRTM modeling software was used to simulate the operation of the plant for each alternative, and estimate aeration energy use and the potential energy recovery from the digester gas. It was shown that improvements to primary sedimentation tank (PST) efficiency achieved by optimization of process operation resulted in benefits for the overall treatment process. It was estimated that for each 1.0% improvement in PST efficiency, the average oxygen requirement in aeration was reduced by 0.67%, and the net energy gain/recovery for the entire plant was 28.5 MJ/1,000 m3 of treated flow ({dollar}0.60/1,000 m3) or 1.8% of the total plant energy use. |
