The Wisconsin DNR regulates pollution discharge to Wisconsin waters through the Wisconsin Pollutant Discharge Elimination System (WPDES) program. Typically, noncontact cooling water (NCCW) defined by the WDNR as “water used for cooling which does not come into contact with any raw material, intermediate or finished product, or waste and has been used in heat exchangers, air or refrigeration compressors, or other cooling means where contamination with process waste is not normally expected,” qualifies for a general discharge permit. However, those using municipal water supplies containing chlorination may not qualify for a general permit without going through a dechlorination process.
Dechlorination Case Study for a Wisconsin Manufacturing Facility
The WDNR required a Watertech customer to dechlorinate discharge from the once through cooling of their NCCW to meet their permit requirements for compliance. This customer was using a municipal water source that was chlorinated. It is important to note that chlorine levels in municipal water are inconsistent and the city periodically changes their disinfectants. These fluctuating levels add another variable to the dechlorination process.
Watertech met this challenge by combining traditional chemistry to dechlorinate the water with technology to treat, monitor, acquire data and provide alarms. Our approach was to assure compliance while treating the water and keeping the system simple.
Watertech worked with the customer and the WDNR to make sure that chemistry used in the treatment was approved for discharge to the storm sewer. Watertech then designed a system with a controller to gather real-time data such as ORP, flowrate and Total Chlorine, then added the chemistry to reduce the ORP and Total Chlorine results. The chemical delivery system increases/decreases the treatment chemical automatically based on the real-time data results. The real-time testing/data acquisition for Total Chlorine (permit requirement) assures compliance at different loadings and provides a history of discharge, if needed. Alarming options in the program are used to indicate if test results are reaching discharge limits and other data points. The data provides Watertech and the customer the assurance that the system is in compliance 24/7 and helps troubleshoot any possible upsets that might occur.
A compliant system that automatically responds to changes in water quality. When the city adjusted the drinking water disinfectants, the system responded with 100% compliance without an involvement from the customer – allowing them to focus on running their plant!
Reach out to Watertech to meet your NPDES noncontact cooling water permit needs.
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Tom Koeppen, PE
Territory Manager, Watertech of America, Inc.