Disinfection and removal of human pathogenic bacteria in arctic waste stabilization ponds

Abstract

Wastewater stabilization ponds (WSPs) are commonly used to treat municipal wastewater in Arctic Canada. The biological treatment in the WSPs is strongly influenced by climatic conditions. Currently, there is limited information about the removal of fecal and pathogenic bacteria during the short cool summer treatment season. With relevance to public health, the objectives of this paper were to determine if treatment in arctic WSPs resulted in the disinfection (i.e., removal of fecal indicator bacteria, Escherichia coli) and removal of selected human bacterial pathogens from the treated effluent. The treatment performance, with focus on microbial removal, was assessed for the one-cell WSP in Pond Inlet (Nunavut [NU]) and two-cell WSP in Clyde River (NU) over three consecutive (2012-2014) summer treatment seasons (late June-early September). The WSPs provided a primary disinfection treatment of the wastewater with a 2-3 Log removal of generic indicator E. coli. The bacterial pathogens Salmonella spp., pathogenic E. coli, and Listeria monocytogenes, but not Campylobacter spp. and Helicobacter pylori, were detected in the untreated and treated wastewater, indicating that human pathogens were not reliably removed. Seasonal and annual variations in temperature significantly (p < 0.05) affected the disinfection efficiency. Improved disinfection and pathogen removal was observed for the two-cell system in Clyde River as compared to the one-cell system in Pond Inlet. A quantitative microbial risk assessment should be performed to determine if the release of low levels of human pathogens into the arctic environment poses a human health risk.

Antibiotic resistance genes in municipal wastewater treatment systems and receiving waters in Arctic Canada

“…The absence of PCR inhibitors was confirmed in spiking experiments as detailed by Huang et al (2017).…”

“…Samples were taken from the influent (septic trucks), and the effluent (decant samples, regulatory compliance point) in September of 2013 and 2014. Operation of the system was previously described by Ragush et al (2015) and Huang et al (2017).…”

“…Samples were taken from the influent (truck) and the effluent (secondary WSP, regulatory compliance point) in June 2013, July 2013, September 2013, June 2014 and September 2014. Additional information about the Clyde River WWTP can be obtained in reports by Ragush et al (2015) and Huang et al (2017).…”

“…Instead, individual homes have wastewater storage tanks, and waste is collected using septic haulage trucks and transported to WSPs located on the edge of the communities (Ragush et al, 2015). New regulations for municipal wastewater treatment (Wastewater Systems Effluent Regulations [WSER], Environment Canada, 2015) have been implemented but are not being applied to Canada's northern regions, since arctic communities would have difficulties complying with the regulations in terms of nutrient and contaminant removal (Holeton et al, 2011;Huang et al, 2017;Ragush et al, 2015). While these regulations are in place to mitigate environmental and health risks, these northern communities are faced with several obstacles (e.g., infrastructure, climate, funding, community capacity, lack of suitable design guidelines, etc.)…”

Screening-level microbial risk assessment of acute gastrointestinal illness attributable to wastewater treatment systems in Nunavut, Canada

“…An indirect exposure assessment method was used to estimate pathogen concentrations at human exposure points within the effluent receiving environment. A dataset of indicator E. coli concentrations in effluent-impacted wetlands and marine waters that had been collected as part of a previous research program was sourced and repurposed (Greenwood, 2016;Hayward et al, 2018;Huang et al, 2017;Neudorf et al, 2017;Ragush et al, 2015). The sampling method involved collecting water samples from treatment system outfalls and at several points within the receiving environments.…”