Design of Cost-effective Coal Washery Effluent Treatment Plant for Clean Environment

Abstract

Coal washery effluents contain large amounts of suspended solids and high COD values and they create serious water pollution problem in which they are discharged. The solids in suspension are colloidal in nature and possess high coking value. Thus in addition to water pollution and siltation on the river bed, good quality of coking coal is being lost. It shows the ineffectiveness of the present effluent treatment system. One large coal washery has been surveyed and the characteristics of the effluent have been evaluated. Treatability study for the removal of suspended solids has been conducted. The effectiveness of the use of different conventional and synthetic polymeric flocculates for the removal o f suspended solids have been evaluated. Studies also involved the identification of a suitable flocculent and to develop a methodology for the effective removal of suspended solids from the effluent. A treatment scheme has been suggested which will make it feasible to design a cost-effective treatment plant for coal washery and the supernatant liquid can be recycled or safely discharged without causing surface water pollution. It would maintain the acceptable balance between environmental management and sustainable development of coal washeries in the region.