Patent ID: 6974544

Claim:
A method for maintaining the hydraulic performance of a micro or ultra filtration membrane during filtration of effluent water containing suspended matter by reducing membrane clogging and improving filtration capacity of the membrane, the method comprising the steps: providing an effluent having as a principal pollutant colloidal organic suspended matters such effluent selectively being, municipal waste water, after a biological treatment and a separation allowing less than 20 mg/l of suspended matter (SM) to be obtained, water not requiring the prior removal of organic matter and having a total organic carbon (TOC) content of less than 2 mg/L, or raw surface water, having a low TOC, a high colloidal concentration and containing less than 200 mg/l of SM; determining the dose (X) of a preselected coagulation reactant that would render the Zeta Potential of the effluent equal to 0; adding a dose of a preselected coagulation reactant to the effluent directly before the effluent passes over the membrane, the added dose being X/30–X/80 and by far insufficient to neither cause complete clarification nor neutralization of Zeta Potential; and directly passing the effluent over the membrane after the dose has been added.