Background: Considering a water shortage crisis, wastewater treatment is essential. One of the most widely used methods of sewage treatment is the activated sludge method. Using this method in wastewater treatment plants produced a lot of sludge. Due to the fertility properties of sludge and its use in agriculture, land reclamation, silviculture and the existence of some heavy metals in sludge and their adverse effects on the soil, groundwater, plants and human beings, evaluation of the heavy metals concentrations is needed.

Materials and Methods: In this study, the concentrations of heavy metals in sludge of wastewater treatment unit in Kaveh industrial city were investigated. Concentrations of Zinc, Chromium, Cadmium, Nickel, Iron, Copper, Lead, Manganese, and Arsenic in the sludge of both the secondary settling tank and thickening tank were determined.

Results: Concentrations of heavy metals were compared with the standard regulations, 40CFR Part 503 environmental protection agency regulations, to determine the levels of these elements and the results showed that the concentration of Lead was higher than the standard limit.

Conclusion: The high lead levels in sludge restrict its use as a fertilizer for agriculture.