TREATMENT OF WATERS WITH MULTIPLE CONTAMINANTS

摘要

A process for a purification of water with multiple contaminants including dissolved solids. The process may involve one or more steps of separating oil and water, metals precipitation, dissolved air flotation (DAF), filtration, forward or reverse osmosis and crystallization. An improved DAF unit is described which increases air dissolution to oxidize impurities and improve flotation. Various embodiments of staged osmotic membrane systems are provided to generate an essentially pure water stream and a highly concentrated solute stream. In some embodiments, reverse osmosis and nanofiltration units are employed in a staged manner. In other embodiments, all stages are reverse osmosis units and the osmotic pressure of each stage is adjusted by the provision of a solution on the low pressure side of the reverse osmosis membrane using nanofiltration membranes. Various recycle options are employed to improve the efficiency of the systems. Also, customized reverse osmosis membrane cartridges and flat reverse osmosis membranes are disclosed.