Biological Effluent Treatment

Recycling of process water in the food industry by combined bioconversion and membrane techniques

An exemplary demonstration of the production of process water from moderately polluted water using a hybrid process showed that it is technically possible. Those that use this application can realize substantial cost savings because they will pay fewer fees for using fresh water and discharge of wastewater. 



Large quantities of process water at the level of drinking water or pure water quality are used in the food and beverage industries. One possibility for saving water is to separate and collect wastewater with a low contamination level (COD values between 2.500 – 6.500 mg/l), purify it using the diaphragm process and then reuse it as process water. However, the high energy consumption required to prevent the build-up of a surface layer on the submersed micro-filtration diaphragm systems has impeded widespread use of this application in practice. 

The main aim of this project was to develop and test the technology for a control principle for automatic switching between filtration and flushing the diaphragm with air (cyclical compressed air flushing). This technology should enable an energy-efficient operation. The system was tested over several months in a fruit juice factory; however, the results can be carried over into other operations in the food and beverage industry. 



  • The hybrid process we developed consists of an aeration unit with submersed MF diaphragms and a downstream nanofiltration unit with integrated UV disinfection capability. 
  • The processed water is partially desalinated and its quality is at the drinking water level. It can be reused within the factory as cooling water or as boiler feed water, for cleaning in the waste or storage areas and for preparing coolant emulsions. 
  • The exact costs for the entire process are between 2.0 to 3.0 Euro/m³ of processed water.

Project Participants

Implementing Institution

Gesellschaft für umweltkompatible Prozeßtechnik mbH (upt)

Cooperation partner

Merzinger Fruchtgetränke GmbH & Co. KG


INTERPLAN Gesellschaft für Rohstoff-, Energie- und Ingenieurtechnik mbH

Paul Rauschert GmbH & Co. KG

Universität des Saarlandes

More Project Information

Project title: Recycling of process water in the food industry by combined bioconversion and membrane techniques

Project number: 0330080

Project period: 1998 - 2002

Project region: Germany (Saarland)

Project contact:

Herr Prof. Chmiel

This email address is being protected from spambots. You need JavaScript enabled to view it.

View Publication

Source: German National Library of Science and Technology Hannover (TIB)