The Purification Of Rainwater With Nanofiltration Membrane

The harvest and reuse of rainwater as a way to help relieve the water shortage is getting increased attention globally, especially in the countries facing water shortage or in rural areas without access to centralized water supply systems. As rainwater generally contains substantial amounts of contaminants including particles, microorganisms, heavy metals, and organics, further treatment of the collected rainwater is necessary. The removal efficiency of contaminants under different conditions was studied in the nanofiltration (NF) process. The results indicated that the optimum conditions in rainwater purification were as follows: the transmembrane pressure 1.0 MPa, the flow rate 30 L/min. The removal rate of chemical oxygen demand was more than 76.5%, turbidity was beyond 95%, the hardness was over 72.4%, and the total nitrogen and phosphorus were in the ranges of 32.5%-33.3% and 17.4%-18.5%, respectively. NF technology effectively removed organic substances and inorganic ions could ensure water safety. After purification, the effluent can meet the drinking water standard.