Box-Behnken Design 기반 반류수 응집처리 시 최적인자 도출에 관한 연구

With the improvement in the water quality standards of sewage treatment plants to treat effluent resulting in recycled water, the introduction of total phosphorus treatment and anaerobic digestion (at pretreatment facilities) have been recently introduced to maintain the quality and reduce the costs of the recycled water. Indeed, recycled water treatment has become a rising issue in the environmental field. However, a high concentration of recycled water may adversely affect a downstream industrial bioreactor. In this study, the amount of recycled water generated at the sewage treatment plant in D city was estimated and analyzed to determine its concentrations in downstream recycled water during different months and seasons. Also, coagulation pretreatment was analyzed, and was found to be achieved via a 17% PAC; the recycled water and its associated optimal flocculant amount were analyzed before it entered the bioreactor. In order to derive the optimum conditions for the coagulation reaction, the Box-Behnken Experimental Design Method was used. Regression, residual, and contour diagram analyses were used to evaluate the removal of CODcr, SS, T-N, and T-P. Consequently, results showed the optimum conditions to undergo the process were determined to be a pH 9 with a rapid stirring at 150 rpm followed by a slow stirring at 50 rpm.