Amelioration of sodic textile wastewater with gypsum before land application

Textile plants produce wastewaters that are frequently high in Na and relatively low in Ca and Mg; such waters are termed sodic. When such wastewaters are applied to land, the Na/(Ca+Mg) imbalance, which is measured by the sodium adsorption ratio or SAR, is detrimental to the soil. One management practice used to counter this effect is the addition of gypsum (CaSO4 . 2H2O) to the wastewater. In this research, the long-term effects of land application of textile wastewaters with different SAR values on the physical and chemical properties were studied. Soil columns using a Cecil series soil were prepared and leached with wastewaters having SAR values of 2, 5, 10 and 20. Soil cation exchange capacity increased at all SAR levels. Soils treated with SAR 10 and 20 wastewaters showed the largest decline in hydraulic conductivity.