Turning Biosolids into Green Energy: Comparing Anaerobic Digestion with Combined Heat and Power to Close-coupled Gasification

Abstract

The Washington Suburban Sanitary Commission performed a study comparing different biosolids management options for its Wastewater Treatment Plants with a focus on energy recovery from biosolids through the methods of drying followed by either gasification or anaerobic digestion with combined heat and power generation. The three phased approach consisting of identifying and screening technologies, performing detailed economic and noneconomic analysis of short listed options, and developing a concept design report for the selected option. Several drying and gasification alternatives were screened but only closecoupled systems were short listed for further analysis. Multiple anaerobic digestion configurations and pretreatment technologies were also screened leading to a short list of conventional mesophilic anaerobic digestion, acid-gas phase digestion and 2PAD. The thermal hydrolysis process was determined to be the most cost effective pretreatment technology to maximize digester gas production. The concept design report was based on a regional facility serving four of the five WWTPs and expandable in the future to accommodate the fifth WWTP.

Dynamics of water innovation : Insights into the rate of adoption, diffusion and success of emerging water technologies globally

“…Many companies in the biosolids management space were anticipating that there would be a regulatory ban on the application of sewage sludge to land. MaxWest Environmental was developing a sludge gasification technology in 2008 to 2014 (Peric et al, 2012). It was competing with land application of biosolids as a lower cost alternative, and this was one factor that meant the market conditions were not ready to drive adoption of sludge gasification.…”