conventional activated sludge (CAS) system, and warm effluent was circulated in the reactor over the winter to keep the liquid from freezing. A metal frame control building was also erected during this first phase of con-struction. The control building includes an electrical room (housing MCC, PLC, VFDs, and transformer), blower room (housing the three biogas blowers, CH4 and H2S detection, gas-liquid separator, biogas oxygen content monitor, and sump pump) and pump room (housing the pumps, heating system for the building and biogas scrubber system, and sump pump). The second phase of construction began in April 2014. It involved the installation of the geomembrane reactor cover and com-pletion of the biogas piping. When the reactor was warm enough, seed sludge was added, sourced from the City of Edmonton’s wastewater treatment plant and waste activated sludge (WAS) from Slave Lake Pulp’s treatment system. By September, the reactor was ready to accept wastewater from the mill. Construction on the biogas scrubber system was completed in 2015. ANAEROBIC PRE-TREATMENT REDUCES COSTS The technical paper by Bertoldo et al. describes the performance and benefits of the new wastewater treatment system. “Canada’s first low-rate anaerobic BVF reactor treating pulp and paper waste-water has achieved the target objectives for improving the performance and effi-ciency of the [Slave Lake Pulp] WWTP, including increased process stability, reduced electrical costs by 43 per cent, lower chemical usage by 50-75 per cent, and reduced waste sludge generation and disposal requirements by 20-25 per cent. Anaerobic pre-treatment has allowed [Slave Lake Pulp] to decommission two of the four existing aeration basins, which has further simplified the overall treat-ment system.” The authors also note that anaerobic effluent quality has been consistent during the variations in incoming waste-water strength. ADI Systems has previously installed several sequencing batch reactors for recycled paper mills in Canada. McCarthy says his company’s BVF low-rate anaerobic digester could poten-tially be used for BCTMP mills and recy-cled-fibre mills. “The technology is good for high-COD streams,” says McCarthy, which may also include some select wastewater streams from kraft, dissolving pulp or other pulp and papermaking operations. Slave Lake Pulp mill generates a high-strength wastewater stream, which prior to the biomethanation project, was treated in a CAS system. This article originally ran in the January/ February 2016 issue of Pulp & Paper Canada. • For more bioenergy and biofuels news, visit www.canadianbiomassmagazine.ca. gy to Ener on.com Biomass 205-663-5330 ocessbarr .pr | www CBM_Process Baron_SeptOct16_CSA.indd 1 Canadian BIOMASS 2016-09-14 11:26 AM 13
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