Salmonellae and pollution indicator bacteria in municipal and food processing effluents and the Cornwallis River

A study was conducted to determine the incidence of fecal coliforms, fecal streptococci, Aeromonas hydrophilia, and Salmonella spp. in the waste discharges of seven sewage treatment plants, four fruit and vegetable canneries, a meat packing plant, a poultry processing plant, and a potato processing plant located along the Cornwallis River in Nova Scotia, Canada. Surface water samples were also collected from 13 locations in the river to assess the impact of these waste discharges on the receiving water quality. The results showed that the final effluents from most of the sewage treatment and processing plants were of very poor bacteriological quality, with the number of indicator bacteria comparable with those found in raw sewage. Salmonellae were isolated from the effluents of the meat and poultry plants and five of the seven sewage treatment plants surveyed. No salmonellae were detected in the effluents of the fruit and vegetable canneries. The impact of the discharge of untreated municipal and food processing wastes on the Cornwallis River water quality was evidenced by the recovery from river water of five Salmonella serotypes, and the high fecal coliform counts which exceeded recommended limit for bathing and shellfish harvesting.