Nearly one quarter of the Canadian population (or eight million) are living in rural and interior regions not connected to centralized wastewater treatment plants, and are served by three million onsite wastewater treatment systems (OWTS). These systems do not have sufficient nutrient removal capacity and pose a threat of eutrophication to receiving water bodies. Possible groundwater contamination by septic tanks is also a major concern. Besides the environmental concerns, there are issues related to the operational efficiency of OWTS. Advanced onsite wastewater treatment system (AOWTS) are required that can address these issues, while producing effluent that is comparable to that produced by centralized conventional wastewater treatment plants. An AOWTS based on Jokaso technology was operated for a period of 21 months, and its performance compared to that of OWTS. The AOWTS consisted of three compartments: a septic chamber (anoxic zone), an aeration chamber (aerobic zone), and a settling chamber. The septic chamber and the aeration chamber contained contact media that promoted biological activity and maintained a high level of performance. At the end of the study period, the ratio of biomass attached to the contact media to biomass in mixed liquor was 2.3 for both the septic chamber and the aeration chamber. The average rates of removal of TSS, CBOD, TKN and TN were 93.4%, 91.7%, 92.8% and 50.5%, respectively. The average concentrations of TSS, CBOD, TKN and TN in effluent were 9.7 mg/L, 8.7 mg/L, 1.5 mg/L and 10.9 mg/L. The effluent from AOWTS was of much higher quality than that from a normal OWTS (or septic chamber).
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