Preliminary Design and Process Control of the City of Richmond, VA Primary Solids Fermentation Facility to Optimize Resource Recovery and Methanol Offset

In order to protect receiving water bodies, states are developing regulations that require increasingly stringent nutrient control by municipal wastewater treatment plants. At the same time, the public is paying closer attention to the rising energy costs and carbon footprints associated with producing high–quality wastewater effluent. Wastewater utilities and their consultants are driven to find value in the very wastewater stream that they are tasked with treating, resulting in innovative, environmentally beneficial, and cost effective strategies. Solids stream management is, of course, an integral aspect of wastewater treatment. As such, the concentration of “resources” into the solids stream provides a great opportunity for targeted resource recovery and nutrient management. The City of Richmond, VA's Nutrient Reduction Program includes the Primary Solids Fermentation Process, which is designed to produce an alternative carbon source for the denitrification process and thereby reduce the methanol demand within the treatment process. This paper will describe the preliminary design and process control of the Primary Solids Fermentation Process at the City of Richmond, VA's wastewater treatment plant.