Local wastewater treatment by effective coagulants based on wastes

Abstract

The purpose of the research was to synthesize new effective and cheap coagulants from industrial wastes (red mud) and study their coagulation properties on model water of textile industries, as well as develop a closed scheme of local wastewater treatment using the synthesized coagulants. Liquid coagulants, synthesized with the simple method, have better performance than commercial FeCl3, since not only iron but also aluminum and titanium compounds are present in the synthesized liquid coagulants, which makes them more effective. For the synthesized coagulants with a dose of 10 mg/l, the removal efficiency of the dyes mixture from the water was 99.7%, while for the commercial FeCl3, with a 2.5 times higher dose - only 95.4%. In the case of creating closed scheme of treatment and usage of the treated water with the coagulation method, an additional sorption purification step from the trace concentrations of pollutants was proposed. The usage of the new coagulants, synthesized from the wastes of alumina production in the proposed scheme will not only help reduce the environmental burden by minimizing the wastewater discharges into sewerage, but also recycle the accumulated environmentally hazardous "red mud" waste into commercial products.