Wastewater Treatment of Stone Cutting Industries by Coagulation Process

Background & Aims of the Study: The wastewater created as a result of stone cuttingindustries enters some pools for re-consumption so that its suspended solids settle bygravity. By taking to account the high volume of water and sludge, treatment of wastewaterand removal of sludge cause many problems for stone cutting units. The objective of thisstudy was to determine the quality of wastewater and to investigate the effects ofcoagulants on suspended solids removal efficiency from wastewater of some stone cuttingindustries (Qom, Iran).Materials & Methods: In this experimental study, the effects of different doses ofcoagulants including Alum, poly aluminum chloride, Polymer, Ferric chloride (Fecl3) andLime on Turbidity, total suspended solids (TSS) and total solids (TS) removal wereinvestigated 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 turbidityremoval and the highest efficiency for TS removal is related to using Alum in dose100 PPM.Conclusions: Considering the findings of this study, it can be concluded that usingcoagulants causes reduction in settling time and speeds up the return of water to theconsumption cycle of stone cutting factories, and also increases turbidity removalefficiency.