Formulation of synthetic greywater as an evaluation tool for wastewater recycling technologies

On-site greywater recycling is one of the main ways of preserving water resources in urban or arid areas. This study aims to formulate model synthetic greywater (SGW) in order to evaluate and compare the performances of several recycling processes on a reproducible effluent. The formulated SGW is composed of septic effluent to provide indicators of faecal contamination, and technical quality chemical products to simulate organic pollution of greywater. To ensure that the SGW developed is representative of household greywater, its analysis was compared to real greywater collected and analysed (RGWs) and to real greywater mentioned in previous publications (RGW(L)). The performance of a direct nanofiltration process with a concentration factor of 87.5% at 35 bar was then tested on both real greywater and SGW. The laboratory experimental results are promising: fluxes and retention rates were high, and similar for both effluents. The permeation flux was higher than 50 L h(-1) m(-2). Retentions greater than 97% for biochemical oxygen demand for 5 days (BOD5) and 92% for anionic surfactants were observed. No Enterococcus were detected in the two permeates. These results confirm that the model SGW developed in this study shows the same behaviour as real greywater when recycled. Thus, the use of this SGW developed in this study was validated for the evaluation of membrane efficiency to treat greywater. This new tool will be a real asset for future studies.