Reduction of water consumption and wastewater quantities in the food industry by water recycling using membrane processes

Due to the rising costs for fresh and wastewater, the treatment and reuse o f low-contaminated process water streams from food processing companies is increasingly gaining in importance. In this study it was shown that water f or reuse could be produced from this water by a specific treatment using me mbrane processes while achieving reduction of water consumption and wastewa ter quantities. Three examples of low-contaminated wastewater will be discu ssed: firstly a vapour condensate from milk processing, secondly chiller sh ower water from the meat processing industry and thirdly wash water from bo ttle washing machines. Due to the promising laboratory and pilot-scale expe rimental results, a demonstration plant with a capacity of 1-2m(3)/h, consi sting of the following stages, was set up: pretreatment; main treatment - 1 st nanofiltration stage; post-treatment - 2nd nanofiltration or low-pressur e reverse osmosis stage and UV water disinfection. Economical water treatme nt was possible in all three examples. The treated low-contaminated process water from chiller showers or bottle washing machines was of drinking qual ity and therefore suitable for reuse. After treatment, the vapour condensat e could be reused as boiler make-up water which is subject to higher standa rds than drinking water. The experimental technology underwent an authoriza tion procedure at the Saarland Ministry for Health, Germany, and was grante d approval.