Application of reverse osmosis techniques to treat and reuse biologically treated wastewater

摘要

Biological treatment together with sorption and clarification techniques are often applied to treat municipal and industrial (petrochemical, food and pharmaceutical) wastewater. Often treated wastewater does not meet technological standards to be reused for industrial purposes such as: cooling, heating, boiler feed or steam generation. Production of quality water for technical needs is implemented through application of reverse osmosis techniques to post-treat water after biological treatment. Reverse Osmosis (RO) provides perfect rejection of all impurities, but also produces concentrate (retentate) streams that often cannot be discharged into surface water. A novel technique is developed and field tested to "hide" concentrate in dewatered sludge (digested sludge after biological treatment and dewatering) that is withdrawn from the system as a sludge moisture. The main goal of presented research was to demonstrate treatment of oil refinery wastewater with reverse osmosis membranes and its separation into product quality water and sludge withdrawn from the system. Industrial application experience to treat storm wastewater, municipal wastewater and petrochemical industrial wastewater is described. Flow diagrams of developed double-stage membrane facilities that ensure high RO recovery are presented, and previously developed tools to withdraw calcium carbonate and magnesium hydroxide from concentrate using "seeding" techniques are disclosed.