Identifying, Then Predicting, Biosolids Loadings for DC Water's Biosolids Management Program …No Small Task!

The District of Columbia Water and Sewer Authority (DC Water) operates the Blue Plains Advanced Wastewater Treatment Plant (AWTP) which treats wastewater from the greater Washington, DC metropolitan area. Recent upward trends in plant influent solids loads, population projections, and ongoing/future plant process upgrades, warrant the need to expand the plant's solids handling capacity. Accordingly, DC Water is developing an innovative Biosolids Management Program (407M) utilizing new and upgraded processes, which include thermal hydrolysis and mesophilic anaerobic digestion, to replace the current lime stabilization operations as the primary means of solids stabilization.One important aspect of the Program is the development of accurate solids production figures from the liquid treatment processes at the Blue Plains AWTP. It is critical that the quantity, quality and source of solids that are produced be thoroughly understood before embarking on the selection and sizing of the required solids processing equipment. Therefore, an early action task of the Biosolids Management Program was the completion of a Technical Memorandum addressing solids production.The objectives of the solids production analysis were as follows:Provide up-to-date biosolids information pertaining to the average and peak solids production from the primary and biological treatment processes at the Blue Plains AWTP.Determine future solids production based on population growth, anticipated liquid treatment upgrade projects, wastewater treatment process options, recycle stream impacts, and new biosolids processing systems.Determine when peak production conditions occur and what peaks may be experienced in the future when existing constraints on solids production are eliminated by various Blue Plains AWTP improvement projects.Develop baseline loadings for the pre-design and design of new biosolids facilities.The focus of this presentation is to show how the existing baseline biosolids production was established and to discuss the factors affecting the future solids production.