기후변화로 인해 전 세계적으로 수온이 상승하는 추세이며, 그에 따른 수계 내 유기물의 농도 증가에 따라 정수 처리 과정에서의 소독부산물 생성량 역시 상승하고 있다. 이 중 총트리할로메탄(Trihalomethanes, THMs)은 발암물질로 분류되며, 먹는 물 수질 기준이 0.1 mg/L로 설정되어 있다. 소독부산물 생성량 증가와 취수원에서의 수질 문제가 지속적으로 제기됨에 따라 안정적 수돗물 공급을 위한 대책이 필요한 상황에서 본 연구는 여름철 경기도와 경상북도 지역의 수도꼭지에서 THMs 농도를 모니터링 하였다. 또한, 과거 THMs 측정 자료와 더불어 다양한 자료를 비교ㆍ분석하여 THMs 농도 변화의 원인을 파악했다. 그 결과, 조사 지역들의 THMs 생성에는 원수의 종류, 그로 인한 용존유기탄소 (Dissolved organic carbon, DOC), 클로로필-a 인자와 더불어 계절적 요인들 중 기온과 강우량이 종합적으로 기여하는 것으로 나타났다. 특히, 선형 회귀분석을 통해 용존유기탄소와 THMs간의 상관관계가 높으며 수돗물의 용존유기탄소 농도가 2.7 mg/L 이상일 경우 THMs 농도가 법정 먹는 물 수질 기준을 초과할 가능성이 높다는 결과를 도출하였다. 이를 통해 여름철 강우가 집중되는 시기와 갈수기 THMs 관리를 위해 원수의 유기물 농도를 관리하는 노력이 필수적임을 확인하였다. 해당 결과는 정수장에서의 유기물 농도 관리를 통해 THMs 생성을 억제하는 것이 매우 중요함을 시사하며, 앞으로 먹는 물 수질 기준과 정수장 운영 관리에 용존유기탄소 수질 항목을 추가하는 방안의 검토가 필요하다 판단된다.

This study is focused on effects of factors that affect the formation of THMs during chlorination in drinking water treatment. During the chlorination, chlorine consumption is increased by increasing the initial chlorine dose, the pH and the total dissolved solid (TDS) concentration. Also THMs formation is increased up to 58.82 μg/L and 55.54 μg/L by increasing initial chlorine concentration and increasing pH. However, concentration of chloroform is decreased by increasing TDS concentration. This is caused the cation(Na+) of the total dissolved solids preferentially reacts with the functional groups of the organic material which influence the trihalomethane formation. But total trihalomethane formation is increased up to 127.46 μg/L by Br- contained in the total dissolved solids. DOC reduction was not influenced by any of the factors.

This study accessed the adsorption characteristics of the 9 trihalomethanes (THMs) on coal-based granular activated carbon (GAC). The breakthrough appeared first for CHCl3 and sequentially for CHBr2Cl, CHBr3, CHCl2I, CHBrClI, CHBr2I, CHClI2, CHBrI2, and CHI3. The maximum adsorption capacity (X/M) for the 9 THMs with apparent breakthrough points ranged from 1,175 μg/g (for CHCl3) to 11,087 μg/g (for CHI3). Carbon usage rate (CUR) for CHCl3 was 0.149 g/day, 5.5 times higher than for CHI3 (0.027 g/day).

This research studied the effect of factors that are able to form disinfection by-products (DBPs) of chlorination, including natural organic matter (NOM) with sewage, bromide ions, pH and contact time. Trihalomethane (THMs) yield of 0.95 μmol/㎎ was higher than other DBPs yield for the chlorinated humic acid samples. THMs yield of sewage sample was 0.14 μmol/㎎ and haloacetonitriles (HANs) yield in the sewage samples were 0.13 μmol/㎎ but only 0.02 μmol/㎎ for the humic acid samples. As the concentration of bromide ions increased, brominated DBPs increased while chlorinated DBPs decreased, because bromide ions produce brominated DBPs. THMs were highest (55.55 ㎍/L) at a pH of 7.9 and haloacetic acids (HAAs) were highest (34.98 ㎍/L) at a pH of 5. Also THMs increased with increasing pH while HAAs decreased with increasing pH. After chlorination, the rate of THMs and HAA formation are faster at initial contact time and then reaches a nearly constant value after 24 hours. This study considers ways to reduce DBP formation by chlorination.

Evaluated were household THMs exposure associated with the use of municipal tap water treated with chlorine and with ozone-chlorine. The current study measured the THMs concentrations in the tap water and indoor and outdoor air in the two types of household, along with an estimation of THMs exposure from water ingestion, showering, and the inhalation of indoor air. Chloroform was the most abundant THMs in all three media, yet no bromoform was detected in any sample. Contrary to previous findings, the fall water THMs concentrations exhibited no significant difference between the chlorine and ozone-chlorine treated water. However, the spring median chloroform concentration in the tap water treated with chlorine (17.6 ppb) was 1.3 times higher than that in the tap water treated with ozone-chlorine (13.4 ppb). It is suggested that the effects of the water parameters should be considered when evaluating the advantage of ozone-chlorine disinfection for THMs formation over chlorine disinfection. The indoor air THMs concentration trend was also consistent with the water concentration trend, yet the outdoor air THMs concentrations did not differ significantly between the two types of household. The indoor to outdoor air concentration ratios were comparable with previous studies. The THMs exposure estimates from water ingestion, showering, and the inhalation of indoor air suggested that, for the residents living in the surveyed households, their exposure to THMs in the home was mostly associated with their household water use, rather than the indoor air. The THMs exposure estimates from tap water ingestion were similar to those from showering.

We have been proposed model equation which is able to predict the trihalomethane producing concentration formation, that is one of byproduct, in the water treatment processes. In proposed model, the effects of trihalomethane factors like chlorine contact time, pH, temperature, TOC and UV-254 are considered. The concentration of the trihalomethane produced is proportion to the contact with chlorine, pH of water, temperature of water TOC and UV-254, respectively. This proposed model could be predicted the formed concentration of trihalomethanes by trihalomethane factors.