Sludge characterization of an industrial water treatment plant, Iran

Abstract

Slurry and cake sludges from an industrial water treatment plant (WTP) were analyzed regarding their physicochemical characteristics and their disposal options. Experiments were carried out in the wet and dry seasons. t-test, Mann–Whitney U-test, and one sample t-test were applied to analyze the obtained data. The results showed that Al, Ca, Cr, Fe, Na, Pb, Se, turbidity, COD and total organic carbon in slurry sludge were significantly higher in wet season than cake sludge. On the other hand, Al, Cr, total solids (TS), FSS, and total suspended solids (TSS) were significantly higher in wet season than dry season. It was also found that in both wet and dry seasons As, Cd, Cr, Na, and Pb were higher in slurry sludge than cake sludge. Moreover, TS, TSS, VSS, and FSS in both seasons were significantly higher in cake sludge than slurry sludge. Canadian soil quality guidelines (CSQG), Florida department of environmental protection soil cleanup target levels (FDEPSCTLs) and land disposal restriction (LDR) of RCRA were used to discuss the disposal fate of the generated sludge. It was found that generated sludge compared with CSQG is not suitable for residential/parkland, agricultural, commercial, and industrial applications. But compared with FDEPSCTLs, it was found that it was just As with higher concentration. Using LDR of RCRA for deciding on the nature of studied sludge indicated that Se concentration is significantly higher than this restriction, indicating that it should be disposes in RCRA Subtitle C class landfill.

Keywords:

• Water treatment plant sludge
• Sludge disposal
• Sludge reuse
• Landfill
• Sludge characterization
• Sludge quality

Acknowledgement

The authors are grateful to Fajr petrochemical company for financial support of this project.