Spiral-wound reverse osmosis systems were tested on acid mine drainage discharges whose water quality characteristics were quite varied. In addition, comparison studies were made of the hollow-fiber and tubular systems and of the spiral and hollow-fiber systems. At all sites, the limiting factor in high recovery operation was calcium sulfate insolubility. Product water was of near potable quality. Neutralization was required in all cases to elevate pH and, in some cases, to remove residual iron and manganese. A 'neutrolosis' process was developed in the course of these investigations and constituted a major technological advance in reverse osmosis treatment of acid mine drainage. The neutrolosis process, a combination of reverse osmosis and neutralization, achieved water recoveries near 99 percent while producing a high quality product. Pretreatment consisted of ten micron filtration. Ultraviolet disinfection, acid injection, or both, were sometimes necessary to inhibit iron oxidation and precipitation.

"Program Element 1BB040." "December 1973." Report prepared by U.S. Environmental Protection Agency, Crown Mine Drainage Control Field Site, Rivesville, West Virginia. Includes bibliographical references (pages 154-155).