METHOD AND APPARATUS FOR PURIFYING AQUEOUS STREAMS CONTAMINATED WITH ORGANIC MATERIALS

摘要

METHOD AND APPARATUS FOR PURIFYING AQUEOUS STREAMS CONTAMINATED WITH ORGANIC MATERIALS. The Aqueous streams contaminated with minor amounts of organic materials are separated into an aqueous fraction which is concentrated with respect to the organic contaminants and a water fraction relatively free of the organic contaminants by a method which includes a unique combination of reverse osmosis (RO) and ultrafiltration (UF). The organic contaminants include substances having molecular weights of less than 10,000 which are soluble in the aqueous stream initially but have limited solubility ranges and are precipitated therefrom upon concentration. The contaminated aqueous stream is circulated from the high pressure compartment of a RO unit to the high pressure compartment of an UF unit, then to the low pressure compartment of the UF unit, and then back to the high pressure compartment of the RO unit. The contaminants are concentrated in the high pressure compartment of the RO unit, and a portion thereof is precipated or otherwise rendered amenable to removal along with the UF concentrate upon passing the RO concentrate from the high pressure compartment of the RO unit to the high pressure compartment of the UF unit. Soluble organic contaminants remaining in the aqueous stream are removed in the UF permeate and are recycled back to the high pressure compartment of the RO unit for further concentration and precipitation, followed by recycling to the high pressure compartment of the UF unit for removal. The above steps are preferably practiced on a continuous basis, thereby producing a substantially pure water RO permeate and an aqueous UF concentrate of the organic contaminants on a continuous basis. The RO permeate may be recycled in industrial processes or otherwise used as fresh water. The UF concentrate may be further processed to recover the organic contaminants for use in industrial processes or for sale as a marketable product, or it may be used as boiler fuel without further processing. The invention also provides improved apparatus which is especially useful in practicing the method of the invention. The method and apparatus of the invention are very effective in treating waste industrial streams which contain small amounts of organic materials such as polyols and organic polymers in general.