Raw Wastewater Filtration to Reduce Secondary Treatment Electrical Energy Deman

Wastewater treatment accounts for a significant portion of municipal energy use. Conventional wastewater treatment uses primary clarification for solids removal and secondary activated sludge treatment for organics removal. Primary filtration is an emerging advanced primary treatment technology that replaces primary clarification with filtration of screened raw wastewater. Compared to primary clarification, primary filtration improves energy efficiency of wastewater treatment by removing greater amounts of solids and organics in the primary treatment step. The project quantified energy savings from primary filtration by implementing a full-scale primary filtration system at the Linda County Water District Wastewater Treatment Plant (2017–2019) and two demonstration-scale systems at the Lancaster Water Reclamation Plant (2017–2018) and the City of Manteca Wastewater Quality Control Facility (2018–2019).
Primary filtration saves energy savings by removing substantially more organic material compared to conventional primary treatment, resulting in much lower electricity consumption for aeration in the downstream biological treatment step and higher digester gas energy production. Estimated annual energy savings range from $22,000 to $35,000 per million gallons per day of wastewater treatment plant average capacity. Additional benefits include lower capital costs, smaller footprint requirements for the primary treatment step, and higher treatment capacity of the biological treatment aeration basins.