Managing Wastewater Carbon Through Innovative Treatment – Full Scale Demonstration of the WASAC Treatment Process at the Chico WPCP

Full-scale validation of the Waste Activated Sludge Anaerobic Contact (WASAC) process was conducted at the City of Chico Water Pollution Control Plant (Chico WPCP). The WASAC process removes chemical oxygen demand (COD) without air, and stores the COD in the waste sludge resulting in increased energy recovery during co-generation. The goals of the project were to successfully operate the WASAC process at full-scale, define operational boundary conditions, and quantify treatment benefits and process kinetics. The data collected demonstrated the WASAC process had no adverse effects on plant effluent quality; removed approximately 40% of the soluble BOD (sBOD) sent to the WASAC process and 20% of the sBOD overall; greater than 90% of the sBOD uptake in the WASAC process occurred within the first 30 minutes. The volatile suspended solids (VSS) content in the WASAC process was consistently higher than the VSS content of the secondary process.