Irrigation and Water Engineering

Irrigation and Water Engineering

Ecological Risk Evaluation of Sewage Sludge to Some Heavy Metals from Municipal Wastewater Treatment Plant in Southern Tehran

Document Type : Original Article

Authors
yousef reza bagheri 1
Ahmad Golchin 2
, Hamed Rezaei 3
Leila Esmaeelnejad 3
1 Ph.D candidate, Department of Soil Science, Faculty of Agriculture, Zanjan University
2 , Department of Soil Science, Faculty of Agriculture, Zanjan University, Zanjan, Iran
3 Soil and Water Research Institute (SWRI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
10.22125/iwe.2024.428680.1775
Abstract
This study investigates the pollution status and environmental risk posed by heavy metals in Sewage Sludge (SS) from the south Tehran wastewater treatment plant. Nine samples were collected and analyzed for Cu, Cr, Pb, As, Ni, Co, and Cd content. Concentrations of Cu (274 mg/kg), Cr (183 mg/kg), and Pb (100 mg/kg) exceeded authorized limits for C1 and C2 sludge grades. Environmental indicators assessed the risk associated with these metals. Single-factor indices (Geoaccumulation and potential ecological risk) identified Cu and Pb as the primary contributors to sludge pollution based on Igeo, while Cd and Cu were most responsible according to Eir. All stations received "low level of contamination" grades for Cr, Cu, and Pb based on the PI value index. Combined indices revealed slight pollution at all stations, as indicated by the Nemerow synthetic pollution index (PN). Potential ecological risk index (RI) indicated low risk for stations 5 and 6, and moderate risk for others. Comparison of combined indices showed differing risk classifications across stations, and trends between indices were not always consistent. High variability in SS composition across stations suggests that applying SS from the south Tehran plant as agricultural fertilizer or soil amendment is not generally recommended
Keywords
Environmental Risk
Geoaccumulation Index
heavy metals
Nemerow synthetic pollution index
potential ecological risk index
Subjects