Wastewater Treatment of Stone Cutting Industries by Coagulation Process

Background & Aims of the Study: The wastewater created as a result of stone cutting industries enters some pools for re-consumption so that its suspended solids settle by gravity. By taking to account the high volume of water and sludge, treatment of wastewater and removal of sludge cause many problems for stone cutting units. The objective of this study was to determine the quality of wastewater and to investigate the effects of coagulants on suspended solids removal efficiency from wastewater of some stone cutting industries (Qom, Iran). Materials & Methods: In this experimental study, the effects of different doses of coagulants including Alum, poly aluminum chloride, Polymer, Ferric chloride (Fecl3) and Lime on Turbidity, “total suspended solids” (TSS) and “total solids” (TS) removal were investigated by Jar Test. Removal efficiency of different coagulates was estimated. Results: The results indicated that lime in dose 100 PPM is the best coagulant for turbidity removal and the highest efficiency for TS removal is related to using Alum in dose 100 PPM. Conclusions: Considering the findings of this study, it can be concluded that using coagulants causes reduction in settling time and speeds up the return of water to the consumption cycle of stone cutting factories, and also increases turbidity removal efficiency.