Treatment of contaminated impound water

Abstract

Systems and methods for treating contaminated impound water are disclosed which include a pretreatment stage wherein contaminated water is oxidized, pH adjusted, treated with a coagulant, and treated with a polymer to form a flocculent comprising bulk solids and fine particles. The oxidizing step may include two or more stages, one of which is a treatment with ferrous iron generated from iron filings or steel wool. Bulk solids are removed, and the liquid portion containing fine particles is applied to a low pressure microfiltration unit to remove the fine particles resulting in a microfilter effluent. The microfilter effluent may be directly fed to a reverse osmosis (R/O) unit. The R/O reject may be recycled to another R/O unit (second pass). The R/O permeate may be blended as needed with the microfiltration effluent to provide the final discharge effluent with reduced contaminant levels and maximized throughput. The R/O second pass reject water is further oxidized and recycled back to the front of the system to be retreated.