Survey on the quality of outlet biosolids and sludge heavy metals in the wastewater treatment plants of Mazandaran province

Background: Sewage sludge is rich in fecal coliforms, Salmonella, parasite eggs, and heavy metals that can cause disease humans. The aim of this study was to evaluate the quality outlet biosolids wastewater treatment plants (WWTP) Mazandaran province compare them with Environmental Protection Agency (EPA) standards. Methods: This carried out on Sari, Joybar, Babol, Babolsar, Nowshahr, Nowshahr-Chalus compost plants. In study, physical, chemical, biological properties samples including retention time, pH, total solids (TS), color, (copper, zinc, nickel, cadmium, chromium) as well density coliform, Salmonella eggs were determined reported. Results: Biosolids WWTP terms class A. Sari summer after drying off naturally located Class A, spring, B based US EPA criteria. average concentration lower than standard. Conclusion: results showed mostly treated sewage WWTPs guideline. these regulation use agriculture not limited for metals.