Green power from biogas By Cindy Macdonald Anaerobic digestion of effluent provides methane for the generators at Slave Lake Pulp. a giant, covered pond filled with microorganisms at the Slave Lake Pulp mill site. It’s man-made, and it’s massive, the size of three hockey rinks. This is a new addition to Slave Lake’s waste-water treatment system and the source of the methane that the mill converts to green electricity. The low-rate anaerobic treatment system is believed to be the first in Canada for the pulp and paper sector. Slave Lake Pulp, a subsidiary of West Fraser Mills Ltd., is a 240,000-tonne-per-year BCTMP mill located in northern Alberta. The mill primarily processes aspen to produce market pulp for the global market. The company decided to explore bio-methane for power generation and requested tenders in 2012. Shannon Fehr, engineering superintendent, says the bid process evoked a wide variety of technologies from around the world. Representatives of Slave Lake went on a trip to China and Thailand to see anaerobic technology in action. Closer to home, they viewed the ADI-Bulk Volume Fermenter (BVF) reactor system in opera-tion in Taber, Alta. The West Fraser team ultimately chose the low-rate, anaerobic BVF system from ADI Systems for the biomethanation with power gen-eration project. General manager Tony McWhannel says the project is part of West Fraser’s commitment to environmental and technical leadership. ADI Systems is a Canadian company, based in Fredericton, N.B. Senior process specialist Peter McCarthy says the selling points of the BVF system are its low need for operator attention, the fact that it doesn’t require granular sludge, and that it is more economical to purchase than high-rate systems. In this particular case, Slave Lake Pulp had sufficient space to install the large-footprint digester. LEFT MAIN: The commissioning team pictured at the biogas scrubbers. INSET: The three 3-MW GE Jenbacher engines can run on both biogas and natural gas. Photos courtesy of Slave Lake Pulp. There’s Canadian BIOMASS 11
Canadian Biomass October 2016: Page 11
