ASSESSING COST-EFFECTIVE ENERGY RECOVERY FROM ANAEROBICALLY DIGESTED WASTEWATER SOLIDS USING A LIFE-CYCLE COSTING TOOL

A life cycle cost (LCC) tool was developed in this research for wastewater treatment facilities that considered a range of anaerobic sludge digestion processes, digester gas pretreatments, and energy recovery systems. This tool provides decision makers in the wastewater industry with a general model that systematically evaluates the economic viability of recovering energy from the anaerobic digestion of wastewater solids.A set of suggested cost functions and default values were derived, based on the survey data of over 40 wastewater treatment plants in the United States and Canada, the quotes of vendors, and an intensive literature review. Sample functions and estimates were introduced in this paper to provide the decision makers with a reference point. However, this tool allows the input of the site specific values.The economic attractiveness of a number of approaches to recover energy from anaerobically digested wastewater solids was evaluated, and the sensitivity of the LCC tool to potential cost variables and parameters was further examined using factorial design.