하수처리장 방류수의 재이용을 위한 2단 PCF/RO 적용에 관한 연구

Abstract

In order to reuse effluent water from Jeju sewage treatment plant, it is necessary to eliminate a highly concentrated Cl- which causes the considerable problems in some areas. Using RO system is considered the best method to get rid of it. As for the pretreatment process, this study is to examine the validity and optimal operating conditions with the fiber filter used in coagulation-sedimentation process. In terms of producing the alternative water resources, this study presented the water quality problems stemming from reuse to understand the reuse potential of the sewage treatment plant(STP) effluent water for agricultural purpose, and also presented the conditions for the stable operation of two-stage PCF/RO that is introduced to solve such problems. In addition, the possibility that the treated water in the two-stage PCF/RO can be used as agricultural water was examined and compared with other standards for overseas and domestic agricultural water. And the following conclusions have been achieved; 1. Based on the results on the optimal condition assessment according to coagulants dosing of two-stage PCF, and waster quality analysis using low SDI15 and COD for fouling prevention, it is determined that 9 ㎖/min dosage is the most stable and effective from the economical aspects depending on filter-run-time 2. Results of the 528 hr operation of two-stage PCF are shown to be adequate for RO pretreatment process because the system did not cause the "breakthrough"effect. Results also indicated the SDI15 below 3.0 and stable treated water, which is appropriate for the application of RO. 3. It is concluded that if the concentration of Cl- and T-N in effluent water is less variable and the target water quality is met, just using two-stage PCF can satisfy the water quality condition for reused water with multi-purpose. 4. Investigation result on adequate treatment when two-stage PCF-treated water was flowed into RO system showed that not only the system was stably operated without any pressure change, but also the excessive Cl- problem that Jeju sewage treatment plant used to have was solved. In addition SS, organic matters, T-N, and T-P, were directly eliminated. Comparison of two-stage PCF/RO treated water quality with standard for domestic and foreign agricultural water resulted in meeting the water quality standards for all analyzed items .