Advancing thermal hydrolysis process for sewage sludge digestion facility in WWTPs

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Sewage sludge management is a significant economic factor in the operation of municipal wastewater treatment plants (WWTPs). In centralized WWTPs, anaerobic digestion (AD) is the most widely exercised process for solids removal and stabilization of sludge. However, efficient removal of solids remains a significant challenge faced by WWTPs. Additionally, the conventional mesophilic AD cannot achieve Class A biosolids for unrestricted land application according to regulatory guidelines. In recent years, thermal hydrolysis of sewage sludge has emerged as a promising method for enhancing AD performance by improving rate-limiting hydrolysis step and thereby producing high-quality biosolids. In this proposed project, the research team will undertake detailed and systematic bench-scale studies to evaluate various process parameters and retrofitting schemes of thermal hydrolysis process (THP) for anaerobic digestion facility at WWTPs. The effectiveness of these schemes will be assessed based on solids reduction, biomethane recovery, quality of biosolids regarding pathogen content, antibiotic resistance genes, dewaterability, odor generation potential, and quality of biogas regarding hydrogen sulfide content, and economic feasibility. Feasibility of further enhancing THP with the addition of chemicals will be examined. A calibrated process model will be developed to provide a design, optimization, and sensitivity analysis tool for various process parameters. Moreover, the preliminary techno-economic feasibility of retrofitting THP will be examined.