HEAT DRYING: THE PREFERRED SOLUTION FOR CLASS A BIOSOLIDS AT ENCINA

The Encina Wastewater Authority (EWA) is implementing a Biosolids Management Program to serve the agency's long-term biosolids management needs through 2025. First, EWA developed a Biosolids Strategic Plan, which was completed early in 2002. The Biosolids Strategic Plan provides valuable information for other agencies embarking upon biosolids management programs. EWA's Biosolids Strategic Plan included an investigation of regulatory issues, facility siting Class A biosolids treatment technologies; a more detailed evaluation of heat drying and pre-pasteurization alternatives using economic and economic criteria; and an assessment of heat dried biosolids product markets in Southern California. Based on the evaluation of both cost and non-cost factors, heat drying using either single or dual trains for redundancy was identified as the preferred option. A potential Southern California market was determined through a telephone survey of local fertilizer companies to determine their interest in a heat dried biosolids fertilizer product. Subsequently, EWA developed the conceptual design of a new solids processing facility that will consist of high solids centrifuges, one or more heat dryer trains, and associated support facilities.