Determination of flocculation characteristics of natural stone powder suspensions in the presence of different polymers

In this study, flocculation behaviors of natural stone powder suspensions were determined by applying classical jar tests. The flocculation tests were performed in the presence of different types of polymers at different polymer dosages and pHs. Then, the settling rates and residual turbidity values of suspensions were recorded. The flocculation performance of flocculants possessing unique molecular architecture (UMA) and conventional polyacrylamide based flocculants was investigated for the solid- liquid separation of natural stone processing wastewater. The effects of flocculant type, dosage and pH were examined. The results obtained from this study indicated that in terms of the settling rate and turbidity, the medium anionic SPP 508 flocculant of 28% charge density showed a better flocculation performance compared to other conventional and UMA flocculants at natural pH. The SPP 508 flocculant gave the lowest turbidity value of 3 NTU (Nepheleometric turbidity Unit) at dosage of 0.3 mg/dm 3 , while the highest settling rate (870 mm/min) for the suspensions tested was achieved at 1 mg/ dm 3 dosage for the same flocculant. However, the lowest settling rate was obtained by high cationic flocculant (Enfloc 440 C). All flocculants showed a good flocculation performance for the settling rate and turbidity at pH 8 and 10.