بررسی میزان فلزات سنگین در لجن آبگیری شده تصفیه خانه فاضلاب ساری

Background and purpose: Dewatered sludge of sewage treatment plants can be used in agriculture if required standards are followed. Heavy metals are among the chemical pollutants that are hazardous to health. Therefore, the aim of this study was to investigate the amount of heavy metals in dewatered sludge of municipal wastewater treatment plant and compare that with the standards and sludge of other wastewater treatment plants in Iran. Materials and methods: In this experimental study, the sludge samples were taken from the sewage sludge in Sari wastewater treatment plant. Sampling and analysis were done during four seasons with three replicates in 2017. The samples were digested and prepared for extraction of heavy metals using standard method. Heavy metal content including Cd, Pb, Cr, Zn, Cu, and Ni was measured by atomic absorption. Data were analyzed using SPSS V24 applying t-test. Results: The average concentrations of Cd, Pb, Cr, Zn, Cu, and Ni were 0.3 ± 0.18, 35.81 ± 9.54, 62.55 ± 14.72, 950 ± 149.93, 354 ± 107.45, and 62.4 ± 18.47 mg/kg dry weight, respectively. Conclusion: In current study the concentrations of heavy metals in dewatered sludge were below the maximum permissible standard of 10716 Iran for compost and other standards. So, dewatered sludge of Sari wastewater treatment plant can be used in agriculture while following all parameters and composting operations.