Anaerobic Digestion of Waste Activated Sludge at Psychrophilic Temperatures with Ozonation to**Reduce Biosolids Production and Enhance Energy Recovery

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The wastewater treatment industry is undergoing a major transformation by increasingly focusing on**wastewater resource recovery instead of simply wastewater treatment. Energy is an important resource that can**be recovered from wastewater, and several facilities aim at operating energy neutral processes. At the same**time, biosolids disposal is a major operational expense as it can use up to 60% of a facilities yearly budget. The**current proposal aims at tackling this combined problem by both minimizing biosolids production and by**maximizing biomethane yields. This will be accomplished though treating waste activated sludge (WAS) with**ozone to enhance it degradability in anaerobic digestion, and though operating the anaerobic digesters at**psychrophilic (20°C and lower) temperatures. The ozone treatment will allow the operation of the**psychrophilic anaerobic digester at high rates, which corresponds to solids retention time (SRT) equal or lower**than 20 days. Thus, beside the decrease in operation temperate, the operation of the digesters will not be**modified substantially from the typical conditions. The enhanced degradability of the WAS will also**potentially create additional process capacity, which may reduce capital investments for the water resource**recovery facilities (WRRF). This new process will be the first of its kind by which the hydrolysis action of**ozone will be used to reduce the digester operation temperature and directly increase the biogas output while**maintaining a relatively low SRT. The current NSERC-CRD proposal is joint with an NSERC-ARD proposal**presented by the Centre National en Électrochimie et en Technologies Environnementales (CNETE; affiliated**with the Collège Shawinigan). The new process developed through the proposed project, which will be**commercialized by Air Liquide and its partners, will likely provide important economic and environmental**benefits to the Canadian wastewater resource recovery industry. It will also generate employment within Air**Liquide and its partners for commercializing, manufacturing, and installing the new processes.