Sustainable Land Development Today - January 2008 - (Page 54) WASTEWATER Cutaway image of an FEG™ ultrafiltration tubular membrane. Each membrane is 10 feet long with a 1” inside diameter. Here, the permeate end is shown with a CPVC shell surrounding a PVDF-casted membrane on a fiberglass, reinforced backing support structure. Membrane System Cost-Effectively Meets New EPA Wastewater Regulations By Tim Jordan As the Environmental Protection Agency (EPA) places more stringent restrictions on the discharge of industrial wastewater, many manufacturers are choosing to outsource their wastewater treatment to companies that specialize in this complex and heavily regulated function. Central Wastewater Treatment of Wisconsin (CWT) is one such wastewater remediation provider. CWT serves more than 35 customers throughout the state of Wisconsin, specializing in removing metal and oil from industrial wastewater and making the water clean enough to be released into a municipal sewage system. CWT processes small batches of wastewater for many different customers who are typically involved in metalworking, such as die casting and machining operations, producing difficult-to-treat wastewater that is high in metal and oil content. The facility meets all the standards and regulations of the EPA, the Wisconsin Department of Natural Resources and the local Milwaukee Metropolitan Sewerage District. Its customers know that wastewater outsourced to CWT will be treated and disposed of properly, according to these regulations. CWT’s closest competitor uses a conventional treatment process that involves adding chemical coagulants along with acids and bases to adjust pH levels and to settle the disposable solids. This process is labor intensive, consumes large quantities of chemicals, and generates a great deal of sludge material. “Although my membrane system required a higher up-front capital investment, I will always have the overall cost advantage because of my lower chemical consumption, labor costs and sludge disposal costs,” Scherff said. He also notes that the significantly lower chemical consumption of membrane systems makes the process safer for employees and significantly reduces the need to manufacture, transport and dispose of chemicals, which also benefits the environment. New EPA Regulations Create Market Opportunity CWT was founded in late 2003 when new EPA regulations made it increasingly difficult for manufacturers to treat their own wastewater. The changes caused several local treatment facilities to go out of business as pre-existing, conventional-treatment facilities could not afford to change their processes to meet stricter EPA guidelines. The 2003 EPA guidelines primarily addressed classification and separation of wastewater streams for treatment. Previously, high concentrations of a contaminant in one type of wastewater could be mixed with other types of wastewater and diluted to an acceptable level. The new regulations do not allow mixing wastewater streams of different types, which forces plants to treat these streams separately. These new requirements created a market opportunity that CWT filled. Cost-Effective and Dependable Membrane Filtration In designing the new wastewater treatment facility, John Scherff, the owner of CWT, sought a treatment system that would reliably and cost-effectively purify the water, meet regulatory requirements and operate automatically with minimal manual intervention. “I knew that membrane filtration technology provides the best treatment method for my application because it provides a positive physical barrier that ensures solids and other contaminants are removed from the wastewater stream,” Scherff said. “The membranes give me and my customers confidence that wastewater is properly and reliably treated according to all environmental regulations.” Reliable filtration is also important because any violation of discharge limits will result in the local sewage district levying fines and imposing a stringent testing regimen to make the plant prove that the problem is corrected. Low Fouling and Easy to Clean CWT initially installed a tubular system, utilizing half-inch nominal diameter membranes. Unfortunately, it brought mixed results. Although the system produced clean discharge water, they were still faced with problems regarding fouling and the system required frequent and time-consuming cleanings. “One of the key reasons for utilizing a membrane system was to reduce labor costs, but we found ourselves spending as much time cleaning the system as we spent processing wastewater,” said Scherff. “We knew almost immediately that we needed to find a different membrane solution.” Rather than purchase a completely new system, CWT decided to retrofit its system to incorporate the one-inch tubu- 54 January 2008 Sustainable Land Development Today
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