애리조나주의 피마(Pima) 카운티 폐수 정화부서가 Tres Rios 폐수정화시설에서 발생하는 소독부산물의 일일 수치를 모니터링하기 위해 아쿠아 계측 시스템(AMS)의 온라인 트리할로메탄(THM)분석기를 구입·설치했다. AMS는 물 속의 부산물을 탐지하는 분석 기기장치 공급업체이다.

지난 2013년 12월 Tres Rios 시설은 온라인 업그레이드로 시설을 확장시킨 바 있다. 이를 통해 궁극적으로 10㎎/l 이하의 유출 수준을 유지하기 위해 다섯 단계의 Bardenpho 프로세스가 암모니아, 질산염 및 아질산염 감소에 사용됐다. 그러나 암모니아 배출량 및 염소 살균 사용의 감소는 총 THM의 형성 잠재력을 증가시켰다.

 

 

 

The Pima County Regional Wastewater Reclamation Department of Arizona has purchased and installed an online trihalomethane (THM) analyzer from Aqua Metrology Systems (AMS), a provider of online and offline analytical instrumentation for the detection of water contaminants, to monitor daily levels of the disinfection byproduct at its Tres Rios Wastewater Reclamation Facility.

 

In December 2013, the expanded and upgraded Tres Rios facility went online. A five-stage Bardenpho process was used for ammonia, nitrate and nitrite reduction, ultimately maintaining effluent levels below 10 mg/l. However, reduced levels of effluent ammonia and the use of chlorine disinfectant increased Total THM formation potential in the discharged effluent.

 

As a result, operations experimented with adding centrate as an ammonia source prior to chlorination to make chloramines since the disinfectant produces lower levels of THMs than chlorine. An online THM instrument, the THM-100™ from AMS, was piloted to characterize and monitor THM formation as a result of this process change.

 

"During the demonstration, we undertook rigorous testing to validate the accuracy, reliability and repeatability of the online THM analyzer by measuring it against results from independent laboratory analysis. The detailed analysis showed that the THM-100 online analyzer provided us with immediate and accurate daily reports on THM levels in our effluent," said Michael Kostrzewski, Department senior project manager. "By monitoring the real-time formation of THMs, following the addition of ammonia, we were better equipped to control its production and implement process optimization techniques accordingly."

 

[출처 = Water World / 2015년 3월 31일]