[미국] 상수도 수질개선 위해 클로라민 제거해야

미국 식수문제가 납 관련 뉴스로 인해 지속적으로 확대되고 있다. 식수에 대한 미국인들의 경각심이 나날이 높아지고 있는 가운데, 최근 텍사스주를 포함한 미국 남서부의 많은 주민들에게 클로라민은 최고의 관심사가 되었다.

전통적으로 상수도의 오염 물질을 제거하기 위해 염소가 사용되었다. 그러나 효율성의 문제로 1930년대부터 염소와 암모니아의 화합물인 클로라민이 이를 대체하게 됐다. 미국 환경보호청(EPA)에 따르면, 현재 미국인 5명 중 1명 이상이 클로라민으로 처리된 물을 사용한다.

하지만 클로라민은 물 속 병원균을 죽이지 못하기 때문에 노인과 어린이와 같이 면역력이 약한 사람들에게 특히 위험하다. 클로라민에 장시간 노출되면 건조, 발진, 가려움증, 색소 침착 등과 같은 피부 질환이 발생할 수 있다. 사람뿐만 아니라 물고기, 양서류, 파충류 등에게도 유해하다.

또, 마이크로칩 제조업체, 의학 관련 업체, 제약 회사, 양조장, 식당 등 대량으로 물을 사용하는 기업은 제조 과정에서 제품이 오염되거나 직원 또는 고객의 건강 문제를 야기할 수 있으므로 클로라민 제거를 위해 적절한 처리 시스템을 설치하는 것이 좋다.

현재 클로라민의 위험성을 매우 심각한 수준으로 보고있지는 않지만, 클로라민을 제거하면 물의 맛이 개선될 뿐만 아니라 특유의 수돗물 냄새를 없애는데도 도움이 된다.

클로라민을 제거하는 가장 보편적인 방법은 코코넛이나 나무로 만든 카본 필터를 이용하는 것이다. 이 필터는 일반적으로 활성탄 가루 또는 바인더로 만든 단단한 블록과 입상활성탄(granular activated carbon , GAC)으로 채워진 셸의 두 가지 형태이다. 이들의 주요 차이점은 카본 블록이 기계적 분리를 추가하는 반면 GAC는 그렇지 않다는 것이다.

클로라민은 염소와 거의 같은 방식으로 물에서 제거되지만 활성탄의 다공성 표면과 더 많은 접촉 시간을 필요로 한다. 탄소 필터의 수명이 다하면 필터는 더 이상 염소나 클로라민을 제거할 수 없으므로 정기적으로 탄소 필터를 교체해야 한다.

클로라민을 제거하는 또 다른 방법은 POU(point-of-use) 역삼투(RO) 시스템이다. 이때, RO 멤브레인에 대한 전치필터(prefilter)로 염소·클로라민 필터가 포함된 다단계 RO 시스템을 사용하는 것이 중요하다. 클로라민이 암모니아와 염소로 분리되면서 RO 시스템의 기능을 저하시킬 수 있는데, 전치필터를 사용하면 RO 멤브레인의 수명을 높일 수 있다. 카본 필터와 달리 RO 시스템은 납, 박테리아와 같은 다른 다양한 오염 물질을 제거한다.

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Kick Chloramines to the Curb

Drinking water concerns continue to escalate in the U.S., with news of lead, chloramines and other contaminants in water supplies putting Americans on high alert about their drinking water. For many residents in Texas and other parts of the Southwest, chloramines have become a top concern.

Thankfully, chloramines can be reduced effectively by various filtration technologies, such as activated carbon.

What Are Chloramines?

Drinking water is treated long before it reaches a household?oftentimes with chemicals to ensure parasites, bacteria and viruses are eliminated. Public drinking water systems traditionally have used chlorine to remove contaminants, but it dissipates quickly. Water treatment plants needed to find a more effective, less expensive way to clean the water, so in the 1930s, water utilities turned to chloramines?the combination of chlorine and ammonia. Chloramines often are referred to in the plural because they can take on a number of forms depending on the pH and mineral content of the water. According to the U.S. Environmental Protection Agency (EPA), more than one in five Americans uses water treated with chloramines.

Consumer Safety Concerns

Shortly after treatment plants switched from chlorine to chloramines, consumer safety questions arose. Numerous studies are being conducted to determine if the use of chloramines is as beneficial as once believed. Researchers are testing two key factors: the effectiveness of ammonia, since it is a food source for bacteria that may cause more bacteria to grow than it eliminates; and the corrosiveness of chloramines when they travel through lead and copper pipe. This article will examine the health risks of chloramines, detection methods and residential treatment methods.

Negative Effects of Chloramines

Health risks of chloramine consumption are well documented. Most notably, chloramines cannot kill pathogens in water, which causes increased health risks for people with weakened or underdeveloped immune systems, like the elderly and children. Prolonged exposure to chloramines can result in skin problems such as dryness, rashes, itching, pigmentation issues and cracking. Chloramines are not currently listed as a serious health concern for humans, but their removal is essential to improving the taste and odor of drinking water.

In addition to the potential risks for humans, chloramines pose a threat to animals. Chloramines are toxic to fish, amphibians and water-based reptiles. Households with fish tanks should use proper methods to remove chloramines to ensure the health of their fish.

Businesses that use large amounts of water to make their products, such as microchip manufacturers, medical supply manufacturers, pharmaceutical companies, breweries, restaurants and photo labs, need to have a proper treatment system installed to remove chloramines, as they could damage products during manufacturing or cause health issues for employees or customers.

Chloramine Detection & Removal

The first question most people ask is, “How do I know if chloramines are in my water?” The easiest way for consumers to research their water supply is to a request a consumer confidence report. These reports outline the levels of contaminants that have been detected in the municipality’s water supply over a certain time period and show how those levels compare with EPA drinking water standards. Water treatment professionals also should offer residential water testing, which can help close the sale of a point-of-use (POU) treatment system.

Once it is confirmed that chloramines are in the water supply, the next step is determining proper removal. The most common treatment method is a carbon filter designed for chloramine removal, usually made from charred and activated coconut or wood. These filters generally come in two basic forms: a rigid block made from powder activated carbon and a food-grade adhesive or binder; or a shell filled with granular activated carbon (GAC). The main difference between the two is that a carbon block offers added mechanical separation, whereas GAC does not.

Chloramines are removed from water in much the same way as chlorine; however, chloramines require more contact time with the activated carbon’s porous surface. Unlike mechanical filtration, the carbon surface actually adsorbs the chlorine or chloramines rather than mechanically separating it. Once a carbon filter’s useful life has been exhausted, the filter will no longer remove the chlorine or chloramines, so it is important for consumers to regularly replace their carbon filters.

Another common method to remove chloramines from water is a POU reverse osmosis (RO) system. It is important to use a multi-stage RO system that includes a chlorine/chloramine filter as a prefilter to the RO membrane. Chlorine and chloramines can degrade the membrane in an RO system, rendering it ineffective. The damage is caused by the dissociation of chloramines into ammonia and chlorine. The use of a prefilter designed for chloramine reduction will significantly increase the life of the RO membrane and the quality of the water. Unlike a carbon filter, RO systems remove a high degree of total dissolved solids from the water, as well as many other contaminants such as lead and bacteria.

In addition to drinking water, consumers often are concerned about the presence of chloramines in the bath or shower. Many showerhead filters are not effective for chloramine removal due to the large volume of water going through the showerhead and the increased flow rate. Should a customer want to remove chloramines in the bath or shower area, a water treatment professional should recommend a whole-house filtration system that uses filters like those outlined above.

Conclusion

Always use reputable manufacturers that design their products for specific contaminant reduction. Certification bodies like NSF Intl., the Water Quality Assn. and UL offer certifications for products to NSF standards for water filtration. Consumers should seek products certified to NSF standards for the removal of chemicals such as chlorine and chloramine. It is imperative that water treatment professionals seek out manufacturers that perform in-house testing or have third-party testing data that prove the filter’s chloramine reduction capabilities.

[출처 = NSF International / 2017년 2월 28일]