In this study, the hydrogen sulfide removal performance of materials that can be used instead of NaOH was evaluated to reduce the amount of NaOH, a harmful substance used in chemical cleaning methods. Three alternative chemical agents were evaluated: commercially available chemical-based CB, enzyme-based EB, and natural substance-based NB. The hydrogen sulfide removal performance evaluation consisted of three lab tests: the EL608 method, a method using a bag, a method using a sensor and a chamber, and a field test conducted on a scrubber in operation in the actual field. As a result of evaluation by the EL608 Method, CB was 92.3% (±2.9%), EB 60.5% (±5.8%), and NB 88.3% (±3.6%), similar or somewhat similar to NaOH (5%) 99.8% (0.1%). In the evaluation of the hydrogen sulfide removal performance using Bag, the Michaelis-Menten coefficient was CB 4.30 and EB 5.30, lower than NaOH 6.60, and the affinity for hydrogen sulfide was evaluated to be stronger. Even in the method using the sensor and chamber, CB and EB showed similar hydrogen sulfide removal performance of NaOH, but NB showed low treatment performance. In the evaluation using the scrubber in the actual field, the treatment efficiency of CB and EB was higher than that of NaOH under all hydrogen sulfide inlet concentration conditions. If microorganisms grow on the packing material filled inside the scrubber, treatment efficiency may decrease. In order to prevent this phenomenon, the microbial growth inhibitory function of alternative materials was evaluated, and CB, EB, and NB were all superior to NaOH. As a result of this study, it was shown that CB and EB can replace NaOH because they have excellent performance in removing hydrogen sulfide and inhibiting microbial growth.

하⋅폐수처리 MBR 공정을 운영함에 있어서 특정 오염물에 따른 멤브레인 회복률 저하를 자주 경험하게 되며, 이에 따른 화학세정 시 막오염 물질 제거에 필요한 약품선택에 많은 어려움을 겪는다. 본 연구의 목적은 하폐수 성상의 MBR 처리 시 발생할 수 있는 Ca 막오염에 대해서 다양한 세정약품 적용을 통한 멤브레인의 회복률 증대 방안을 찾고자 하는 것에 있다. 본 연구는 K 폐수처리시설에서 1년간 운영한 (주)에코니티의 분리막을 샘플링하여 투과도 측정 및 막표면 분석 후 막오염 물질을 우선적으로 확인하였으며, 이에 따른 각종 화학약품의 적용실험을 통하여 최적약품 도출 및 적용성을 평가하고자 하였다.

In the present study, the impact of RO polyamide layer by long-term chemical exposure was evaluated. Basic cleaning chemicals such as NaOH increased the pure water flux and salt passage of RO membrane up to 1.6 times and 2 times, respectively. In contrast, membranes exposed to acidic chemicals such as HCl have experienced no discernible change of permeability, which indicated that basic chemicals caused the more serious damage to RO polymeric layers. However, XPS analysis showed that both membranes were experienced significant damages on cross-linking of polyamide structures. It can be concluded that basic cleaning chemicals induced the enlarged pore structure due to electrostatic repulsion between damaged polymers, while acidic chemicals caused less performance deterioration by shrinkage of the polyamide structure.

In water treatment process using microfiltration membranes, manganese is a substance that causes inorganic membrane fouling. As a result of analysis on the operation data taken from I WTP(Water Treatment Plant), it was confirmed that the increase of TMP was very severe during the period of manganese inflow. The membrane fouling fastened the increase of TMP and shortened the service time of filtration or the cleaning cycle. The TMP of the membrane increased to the maximum of 2.13 kgf/cm2, but it was recovered to the initial level (0.17 kgf/cm2) by the 1st acid cleaning step. It was obvious that the main membrane fouling contaminants are due to inorganic substances. As a result of the analysis on the chemical waste, the concentrations of aluminum(146-164 mg/L) and manganese(110-126 mg/L) were very high. It is considered that aluminum was due to the residual unreacted during coagulation step as a pretreatment process. And manganese is thought to be due to the adsorption on the membrane surface as an adsorbate in feed water component during filtration step. For the efficient maintenance of the membrane filtration facilities, optimization of chemical concentration and CIP conditions is very important when finding the abnormal level of influent including foulants such as manganese.