엔바이로젠 테크놀로지(Envirogen Technologies)는 환경 기술에 대한 해결책을 제공하는 기업으로, 캘리포니아주 살리너스(Salinas) 지역에 상하수도 서비스 및 식수 공급을 위해 6가크롬의 처리방식과 관련된 고효율 이온교환(ion exchange, IE) 시스템을 성공적으로 도입했다고 최근 발표했다.

 

이는 완전하게 정비된 시스템을 첫 도입하는 것으로, 캘리포니아의 식수 분배를 위한 이번 6가크롬 처리방식은 지난 2014년 7월부터 10 μg/L(마이크로그램/리터)였던 최대오염 수준을 새롭게 제시한다.

 

 

 

Envirogen Technologies Inc., an environmental technology and process solutions provider, recently announced the successful startup of a high-efficiency ion exchange (IE) system for the treatment of hexavalent chromium (hex chrome) in drinking water supplies for California Water Service (Cal Water) in Salinas, Calif.

 

This is the first permitted full-scale system to go online for treating hex chrome since California's Division of Drinking Water (DDW) released a new maximum contaminant level (MCL) of 10 μg/L (10 micrograms per liter) in July of 2014. The IE system will treat groundwater sourced from a well in the Cal Water system to be more than 20 percent lower than the MCL.

 

The selection of Envirogen's technology was based on a system design that offers a high level of reliability, low waste and disposal rates and the lowest lifecycle cost. The system was designed, manufactured, installed, and started up in less than 90 days from project go-ahead. A second IE system is planned to come online for Cal Water this summer. These systems represent the eighth and ninth systems provided by Envirogen and in operation for Cal Water to treat drinking water -- with the previous systems treating nitrate and perchlorate.

 

For Cal Water, the IE system features a multi-vessel bed design that operates in a staggered configuration, blending the water from each vessel and producing a consistent treated water quality. Depending on the flow range, between eight to 13 vessels are online at any time, with three vessels in regeneration or standby. These systems utilize Envirogen's patented, counter-current, cascading bed regeneration process to minimize waste, resulting in one bed volume of waste per regeneration cycle and allowing waste rates as low as 0.01 percent.

 

The largest component of the operating cost associated with most IE systems is waste handling. For hex chrome treatment, the IE waste brine may be a Federal hazardous waste (i.e. Cr > 5 mg/L) that is expensive to dispose of directly. Envirogen's solution for Cal Water is a Brine Processing Unit (BPU) that converts hex chrome to a less hazardous, trivalent chromium that is then precipated using an NSF-61-approved coagulant. The result is a non-hazardous liquid brine waste and a small volume of 2 percent solid waste. The process units -- IE and BPU -- were containerized for rapid deployment at the Cal Water wellhead, allowing a small facility footprint.

 

[출처 = Water World / 2015년 7월 13일]