Fermentation: Unleashing the Power and Making it Work

The Douglas L. Smith Middle Basin Treatment Plant (DLSMBTP) was upgraded in 2008 to full biological nutrient removal (BNR) capabilities to meet effluent goals of 1.5mg/L of total phosphorus (TP) and 8 mg/L of total nitrogen (TN). Data had shown that the influent quality was low in soluble biochemical oxygen demand (BOD) and subsequent BioWin modeling demonstrated that the plant was carbon limited. A batch test demonstrated that sufficient volatile fatty acids (VFAs) or readily biodegradable chemical oxygen demand (COD) could be liberated through the fermentation of primary sludge. The treatment plant site was severely restricted and fitting the fermenter onto the site was difficult. Integrating the fermenter with the site hydraulic profile, odor control system, and supervisory control and data acquisition (SCADA) system posed a number of unique challenges. While the fermenter did improve biological phosphorus removal (BPR), mechanical issues interfered with fermenter operability.