Phosphorus Removal: Field Analysis

The Great Lakes Water Quality Agreement of 1978 established by the International Joint Commission of Canada and the United States called for the achievement of 0.5 mg/l total phosphorus as the maximum effluent level in all Lake Erie and Lake Ontario municipal wastewater treatment plants discharging greater than 3785 m³/day. A study was undertaken to provide information necessary to review and evaluate the above objective. Four municipal treatment plants practicing phosphorus removal were evaluated by field monitoring. In addition, the costs associated in the phosphorus removal at each of the four plants were studied. The field studies indicated that a conservatively operated plant using a conventional approach could achieve an effluent level of ≤ 0.75 mg/l, and in some cases lower, without filtration. The design of the final sedimentation tanks, in terms of loadings, appears to be a critical factor.