본 연구는 하수를 공업용수로 재이용하기 위한 분리막 시스템 적용에 관한 연구이다. 정밀여과와 역삼투시스템으로 구성된 bench scale 실험장치를 이용하여 하수처리장 현장에서 실험을 수행한 결과, 정밀여과 시스템은 이온성분은 제거할 수 없었으나 SS를 70% 이상 처리할 수 있어 처리수는 직접냉각수로 재이용이 가능하였다. 그리고 역삼투 시스템은 SS는 물론 이온성분도 95% 이상 제거할 수 있어 처리수는 간접냉각수 및 제품세척수로 사용이 가능하였다. 100 m3/일 용량의 pilot Plant를 제작하기 위해서는 정밀여과 모듈은 20개, 역삼투 모듈은 12개가 필요하였다.

Sequencing Batch Reactor(SBR) experiments for organics and nutrients removal have been conducted to find an optimum anaerobic/anoxic/aerobic cycling time and evaluate the applicability of oxidation-reduction potential(ORP) as a process control parameter. In this study, a 6 ℓ bench-scale plant was used and fed with night-soil wastewater in K city which contained TCODcr : 10,680 ㎎/ℓ, TKN : 6,893 ㎎/ℓ, NH_4^+ -N : 1,609 ㎎/ℓ, PO_4^3- -P : 602 ㎎/ℓ on average. The cycling time in SBRs was adjusted at 12 hours and 24 hours, and then certainly included anaerobic, aerobic and anoxic conditions. Also, for each cycling time, we performed 3 series of experiment simultaneously which was set up 10 days, 20 days and 30 days as SRT. From the experimental results, the optimum cycling time for biological nutrient removal with night-soil wastewater was respctively 3hrs, 5hrs, 3hrs(anaerobic-aerobic-anoxic). Nitrogen removal efficiency was 77.9%, 77.9%, 81.7% for each SRT, respectively. When external carbon source was fed in the anoxic phase, ORP-bending point indicating nitrate break point appeared clearly and nitrogen removal efficiency increased as 96.5%, 97.1%, 98.9%. Phosphate removal efficiency was 59.8%, 64.5%, 68.6% for each SRT. Also, we finded the applicability of ORP as a process control parameter in SBRs.

In the study, we investigated the behavior and removal efficiency of organics, nitrogen, phosphorus with operating conditions in SBRs. Substrate used was synthetic wastewater in which the ratio of COD_cr : N : P was 100 : 12 : 2. The cycling time in SBRs was adjusted at 6 hours and 8 hours, and then certainly included anaerobic and aerobic conditions. Also, for each cycling time, we performed 2 series of experiment simultaneously which was set up 10 days and 20 days as SRT. The removal efficiency of COD_cr, was over 97% in all operating conditions. In the 6 hours cycling time, the removal efficiency of PO_4^3- -P reached almost 100% in steady state. And then we could observe a typical phenomena of phosphorus release and uptake, and the removal efficiency of N was 67%. Residual N source was almost TKN and most of the rest remained as NO_2^- -N. Also the difference in both SRTs was not observed practically. In the 8 hours cycling time, dissolution of sludge appeared. and, PO_4^3- -P was not nearly removed but nitrogen was removed up to 75%. And the residual nitrogen was accumulated as NO_2^- -N.