Rehabilitation of Copper Mine Tailing Slopes Using Municipal Sewage Effluent

Abstract

The suitability of treated municipal sewage effluent for the irrigation of deep- rooting plant material for the rehabilitation of copper mine tailings was studied at the Cyprus Pima Mining Company. The effectiveness of treated sewage effluent was compared with well water on the growth and survival of trees, legumes and grasses. The species studied were eucalyptus (Eucalyptus rostrata), native mesquite (Prosopis juliflora), palo verde (Cercidium floridum), desert tobacco (Nicotiana lauca) barley (Hordeum vulgare), perennial rye grass (Lolium perenne), alfalfa (Medicago sativa), and blue lupine (Lupinus augustifolius). Sprinkler and tree -well irrigation methods were used to apply the treated sewage effluent and well water to steep tailing slopes. The treated municipal sewage effluent was found to be a practical irrigation substitute for well water and a good source of plant nutrients such as nitrogen and phosphorous. Effluent produced better survival and growth than did well water with or without augmentation.