Laserfiche WebLink
Evaporation-A Wastewater Treatment Alternative Page 4 of 5 <br /> Most installations can produce a distillate TDS of less than 10 mg/I, and in some cases, <br /> less than 2 mg/I. <br /> Not only does the recovered water from an evaporator meet most discharge <br /> specifications, it can almost always be recycled for reuse in manufacturing or cooling <br /> applications. In one metal finishing installation, distillate was recycled as process rinse <br /> water at a volume ten times less than the quantity of city water required to do the job. <br /> Evaporators can minimize the production of regulated waste residues, and increase the <br /> potential for recovering valuable metals from those wastes. Unlike ion exchange, <br /> evaporation is not as sensitive to traces of oil, and does not produce regeneration wastes <br /> that require additional treatment. <br /> Metal finishing: The metal finishing industry today makes use of the "electroless" plating <br /> process, for instance in the manufacture of printed circuit boards. This produces a hard-to- <br /> treat waste stream that contains chelating agents such as organic acids (e.g., EDTA) or <br /> ammonia, which prevent the normal precipitation of heavy metal hydroxides. Additional <br /> chemicals must be added to break down the chelating agents prior to conventional <br /> treatment. However, evaporation has been used successfully on these wastes without the <br /> need for other reagents. <br /> Operating Cost Evaluation <br /> A cost comparison of two wastewater treatment alternatives considered for use at a metal <br /> finishing facility in the Northeast is shown in Table 2. The preliminary study evaluated <br /> several treatment approaches, but concluded that an evaporation system <br /> (evaporator/crystallizer) and a conventional chemical precipitation system <br /> (neutralization/precipitation/polishing) both would be capable of producing a satisfactory <br /> effluent. However, only the evaporation system could produce water of a high enough <br /> quality for reuse. While the precipitation system was rated at 395 I/min, the evaporation <br /> system was rated at 190 I/min, reflecting its ability to reuse evaporator distillate as process <br /> rinse water. <br /> About the Author: <br /> Tom M. Pankratz is the Middle East regional manager for Aqua-Chem, Inc., based in <br /> Dubai, United Arab Emirates. <br /> Deck: <br /> Wastewater Treatment <br /> By Line: <br /> Tom M."Pankratz <br /> Share: Facebook t,i Twitter[21 Linkedln [3] <br /> Activation Date: <br /> December 28, 2000 <br /> Files: <br /> 141 evaporation RS.pdf(41 <br /> F Legacy i <br /> http://www.estormwater.com/print/4458 11/28/2012 <br />