Performance of municipal waste stabilization ponds in the Canadian Arctic

•We monitored 4 arctic Wastewater Stabilization Ponds in the summers of 2011–2014.•Systems were found to be generally anaerobic due to the climate and organic loading rates.•Monitored arctic WSPS effectively removed TSS but were challenged to reduce CBOD5.•Deeper cells improved TSS removal, but negatively impacted CBOD5.•A multi-cell system is recommended to improve treatment performance.

The majority of small remote communities in the Canadian arctic territory of Nunavut utilize waste stabilization ponds (WSPs) for municipal wastewater treatment because of their relatively low capital and operational costs, and minimal complexity. New national effluent quality regulations have been implemented in Canada, but not yet applied to Canada's Arctic due to uncertainty related to the performance of current wastewater treatment systems. Waste stabilization pond (WSP) treatment performance is impacted by community water use, pond design, and climate. The greatest challenge arctic communities experience when using passive wastewater treatment technologies is the constraints imposed by the extreme climate, which is characterized as having long cold winters with short cool summers that can be solar intense. The removal of carbonaceous biochemical oxygen demand (CBOD5), total suspended solids (TSS), and ammonia-nitrogen were measured during the summer treatment period (late June until early September) from 2011 to 2014 in the WSP systems of four Nunavut communities; Pond Inlet, Clyde River, Grise Fiord and Kugaaruk. Monitoring results showed that WSPs in their current single cell design can achieve greater than 80% removal of CBOD5 and TSS but were challenged to produce effluent quality that meets secondary wastewater treatment standards (<25 mg/l CBOD5 and TSS). This study points to the need for revisions of design guidelines for facultative WSPs in the Arctic, as current systems are anaerobic and do not contain sufficient dissolved oxygen required to consistently support aerobic biological treatment processes.