Forward osmosis treatment of effluents from dairy and automobile industry - results from short-term experiments to show general applicability.

Forward osmosis (FO) is a potential membrane technology to treat wastewater energy efficiently with low fouling. In laboratory-scale experiments, six effluents from a dairy and an automobile production plant were tested to find out if FO is an applicable treatment technology. Permeate flux and reverse salt flux were determined in nine test series with three subsequent 5 h experiments each. In between, the membrane was cleaned with deionized water. Membrane performance tests before each experiment were used to monitor membrane performance and fouling. Samples were analysed and the T/M-value was introduced to indicate which substances caused fouling. Dairy cheese brine was a suitable DS. Here, permeate fluxes were 21.0 and 15.1 L/(m²·h). Automobile cooling tower water and wastewater from cathodic dip painting were also used as DS. However, permeate fluxes were below 1.1 L/(m²·h). The tested FS, reverse osmosis concentrate from dairy wastewater treatment, rinsing water and wastewater from automobile cathodic dip painting, as well as wastewater from automobile paint shop pre-treatment, showed good performance regarding the permeate flux of between 7.9 and 19.4 L/(m²·h). Membrane performance test showed that some of the effluents lead to permeate flux reduction due to fouling. Different cleaning-in-place methods were examined. Eventually, permeate flux was restored.