A Study on the Potential Evaluation of Power Independence by Improvement of Organic Matter Recovery Rate at Sewage Treatment Plant

Abstract

　Toward achieving power independence at sewage treatment plants, a performance evaluation system (PES) was used at four sites with a treatment capacity of 100,000 to 150,000 m³ day^-1, to estimate the power self-sufficiency. For enhanced organic matter recovery, pre-coagulation method and contact stabilization process were selected for ease of introduction. When the pre-coagulation method was introduced, the BOD capture rate increased to 70- 81% due to the increase in the primary sludge recovery rate and the amount of electricity used decreased by 2 - 7%, the power self-sufficiency rate improved to 29.7 to 58.0%, and it was 1.13- 1.24 times the current status. When the contact stabilization process was introduced, the BOD capture rate increased to 68- 79% due to the increase in the excess sludge recovery rate and the amount of electricity used decreased by 1 - 9%, the power self-sufficiency rate improved to 25.5to 57.3%, and it was 1.02- 1.13 times the current status. Looking toward the power independence, it was considered important to evaluate the performance as a whole sewage treatment plant, including the introduction of energy-saving nitrogen treatment technology such as nitrite shunt and anammox, in addition to the BOD capture.