Low temperature (psychrophilic) in storage digesters have been used for years in many temperate parts of the world – mainly developing countries – as a way to treat human and livestock waste and provide cooking fuel. They are cheap to construct – just throw an impermeable cover over an existing manure pond or storage tank – and can help control odors
and stop nitrification. King, a PhD student in the Department of Bioresource Engineering at McGill University in Quebec, is studying psychrophilic digestion at a commercial-scale swine operation located near St. Francois-Xavier, Quebec, in the Eastern townships by the Canada-U.S. border. The farm owner had decided to cover his existing manure storage tank as a way of controlling odor. A polymer membrane floating cover, designed by Geomembrane Technologies Inc. (GTI) of New Brunswick, was constructed on top of the 100-foot wide by 12-foot deep concrete storage tank. The tank’s sides were surrounded by soil and plastic pipes filled with concrete are used to keep the cover from lifting off the surface. King’s specific interest in the system involves the role played by microbial communities within the manure storage system and how quickly they can acclimate to different temperatures. She recently discussed her research during the First Annual Canadian Farm & Food Biogas Conference in Ontario, Canada. King hopes to continue her research and examine nitrogen conservation and land application of manure from an In Storage Psychrophilic Anaerobic Digestion (ISPAD) system, including wind tunnel tests to see what is released at application. She hopes to monitor two more swine production sites using covered manure tanks and optimize the ISPAD design.