by R. Penn, M. Schütze and E. Friedler
On-site greywater reuse (GWR), in the urban sector, reduces urban demand of fresh water resources. In the last years research on GWR has generally overlooked the effects that GWR may have on municipal sewer systems. This paper discusses and quantifies these effects. The effects of GWR, positive and negative, were studied by modeling a representative urban sewer system. Five GWR scenarios were modeled and analysed using the SIMBA simulation system. The results show that as expected as GWR increases, the flow, velocity and proportional depth decrease. Nevertheless, the reduction is not evenly distributed but mainly occurs during the morning and evening peaks. Further, it is indicated that as a result of the GWR, blockages rate of sewers is not expected to increase. The results support the possibility to construct new sewer systems with smaller pipe diameters. The analysis shows that as the penetration of GWR system increases, concentrations of pollutants increase too, but at a rate lower than proportional reduction of sewage flow.