Studies were undertaken on a small scale to determine the effect liquid waste artificial iron-rich acid brines had on municipal sewage treatment processes. The brines were devised to simulate concentrates from treatment of acid mine drainage. At very high concentrations, the brines neutralized with lime give virtually complete removal of phosphate from primary effluent, activated sludge effluent, or anaerobic sludge digester decantate. The cost of the iron-rich acid brine produced from acid mine drainage by the reverse osmosis membrane treatment is estimated. Costs of transportation by rail, truck, and pipeline are also shown.

Bench scale batch experiments were performed on sludges obtained from line neutralization of coal mine drainage in an attempt to alleviate present problems in sludge handling and disposal. Tests were of an exploratory nature and did not afford sufficient data for cost analyses. Ferro Magnetic sludge densification, filter aids, coagulant aids, heating, freeze drying, and coprecipitation of calcium carbonate through addition of CO₂ were tested. Of these, freeze drying, CO₂ addition, and ferro magnetic treatment were shown to be feasible alternatives to present disposal methods. Each of these methods resulted in settled sludge volume reduction of approximately 90% and increases in sludge solids contents of from 0.5 to about 5% after 30 min. settling periods. The ferro magnetic process has the advantages of possible recovery of a useful product, and elimination of costly settling lagoons, but is very sensitive to aluminum and requires a considerable amount of heat. Sludge freezing is the simplest conceptual approach and is apparently effective for any lime produced sludge. The CO₂ addition method offers the possibility of partial recovery and recycling of both CaO and CO₂ through sludge calcination.

A project has been underway which attempts to demonstrate practical means of abating pollution from coal mine mineral wastes. The site included a refuse pile occupying approximately 40 acres and a slurry lagoon complex of 50 acres. In the report, the characteristics and acid formation rate of the refuse pile are described. The average rate of acid formation for this refuse pile is 198 pounds of acidity, as CaCO₃, per acre per day. Acid contribution from the slurry lagoons was not determined but appears to be negligible. As an abatement measure, a number of experimental vegetative covers were tested. Grass was successfully established with and without the use of topsoil, weathering well for one year. The long-term effects of establishing a grass cover directly on the refuse without the use of topsoil are not known at this time.

Experiments up to 150 days in length were conducted to study the acid production rate of coal mine pyrites under various gas atmospheres. The gas atmospheres studied were air, nitrogen, methane, and carbon dioxide. The lower limits of the oxidation process were studied by introducing small amounts of oxygen along with the inert blanketing gas and by studying the effects of deaerated versus air saturated feedwater. Acid production was proportional to the available oxygen partial pressure. The acid parameters monitored continued to change and had not completely reached a steady state by the termination of the work. The acid production of nitrogen blanketed pyrite decreased to less than 1% of that of identical columns under air atmosphere. Nitrogen and methane gases were equally effective in reducing acid production. Both of these gases were slightly more effective than carbon dioxide. A large amount of detailed experimental data is presented.