Purification of copper wire drawing emulsion by application of UF and RO

Due to the rising costs for fresh and wastewater, the treatment and reuse of low-contaminated process water streams from food processing companies is increasingly gaining in importance. In this study it was shown that water for reuse could be produced from this water by a specific treatment using membrane processes while achieving reduction of water consumption and wastewater quantities. Three examples of low-contaminated wastewater will be discussed: firstly a vapour condensate from milk processing, secondly chiller shower water from the meat processing industry and thirdly wash water from bottle washing machines. Due to the promising laboratory and pilot-scale experimental results, a demonstration plant with a capacity of 1¯ 2m3/h, consisting of the following stages, was set up: pretreatment; main treatment ¯¯ 1st nanofiltration stage; post-treatment ¯¯ 2nd nanofiltration or low-pressure reverse osmosis stage and UV water disinfection. Economical water treatment was possible in all three examples. The treated low-contaminated process water from chiller showers or bottle washing machines was of drinking quality and therefore suitable for reuse. After treatment, the vapour condensate could be reused as boiler make-up water which is subject to higher standards than drinking water. The experimental technology underwent an authorization procedure at the Saarland Ministry for Health, Germany, and was granted approval.