Abstract: Advanced submerged membrane systems are provided. Said submerged membrane systems have multiple membrane modules comprising of strips of flat sheet membrane, bundles of self-support hollow fiber membranes braided together for reinforcement, tubular membranes, and braid supported hollow fiber membranes. Said submerged membrane systems have alternating relay, or two-way floating switch or computer to control filtration and back flush/pulse cleaning. Said submerged membrane systems have an oscillating motor, and aerator which can generate liquid vortex (whirlpool) flow around membrane to keep membrane from fouling. The present invention provides advanced submerge membrane systems at very low cost for drinking water production, wastewater treatment and membrane bioreactors for biotech, pharmaceutical and other industries.

Abstract: A defect free semipermeable composite membrane having excellent integrity and high water permeability is provided. Said composite membrane comprises an inside support layer to provide sufficient mechanical strength; an outside barrier layer to provide selective separation; and a middle layer to provide both physical adhesion and chemical binding between said support and said barrier layer to bond them together. Three different methods for making said defect free composite membrane are discovered. These methods have been successfully utilized to produce high quality coatings and defect free composite membranes, which are independent of chemical composition and physical structure of said support. In the present invention, ultrasonic sonication is discovered to be effective to speed up the phase inversion process of a membrane casting solution, thus allows produce a composite membrane at a speed much higher than those disclosed in the prior art.