Reuse of greywater and rainwater using fiber filter media and metal membrane

As water resources become more limited and waste discharge becomes increasingly problematic, the concept of water reuse is becoming important. Recently, use of greywater and rainwater as alternative water resources has drawn attention. However, lack of useful information on the combined use of greywater and rainwater hinders wide application of these systems. In this study, novel treatment options including lignocellulose filter media and metal membranes were examined to reuse greywater and rainwater in office buildings. Laboratory scale experiments were performed to evaluate the potential of these technologies. The fiber filter media was useful to control first flush rainwater but was not enough to produce water for non-potable use in buildings. Thus, the metal membrane filtration was attempted to reject particulate pollutants. The removal efficiency of various pollutants and the membrane permeability were examined using metal membranes with different pore sizes.

In this study, the feasibility of treatment techniques using the fiber filter media and metal membranes were examined for reuse of greywater and rainwater. The following conclusions were drawn: (1) The fiber filter media removed not only particles but also nutrients such as nitrogen and phosphate. The integration of the fiber filter media into first flush treatment unit allowed efficient treatment of rainwater under various conditions. (2) The metal membranes efficiently rejected particles in greywater and rainwater. The metal membrane having larger pore size resulted in slower fouling but lower rejection. It is evident that the treatment of rainwater costs much less than that of greywater.