Disposal Situation of Sewage Sludge from Municipal Wastewater Treatment Plants (WWTPs) and Assessment of the Ecological Risk of Heavy Metals for Its Land Use in Shanxi, China

Baoling Duan, Wuping Zhang, Haixia Zheng, Chunyan Wu, Qiang Zhang and Yushan Bu
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Baoling Duan: College of Resources and Environment, Shanxi Agricultural University, Taigu 030801, Shanxi, China
Wuping Zhang: College of Resources and Environment, Shanxi Agricultural University, Taigu 030801, Shanxi, China
Haixia Zheng: College of Resources and Environment, Shanxi Agricultural University, Taigu 030801, Shanxi, China
Chunyan Wu: College of Resources and Environment, Shanxi Agricultural University, Taigu 030801, Shanxi, China
Qiang Zhang: College of Resources and Environment, Shanxi Agricultural University, Taigu 030801, Shanxi, China
Yushan Bu: College of Resources and Environment, Shanxi Agricultural University, Taigu 030801, Shanxi, China

IJERPH, 2017, vol. 14, issue 7, 1-12

Abstract: Land use of sewage sludge is the primary disposal method in Shanxi, accounting for 42.66% of all. To determine the ecological risk of heavy metals in sewage sludge, contents of seven heavy metals in sewage sludge from 9 municipal waste water treatment plants (WWTPs) that had the highest application for land use were determined. The order of the measured concentrations was: Zn > Cr > Cu > Ni > Pb > As > Cd, and all heavy metals contents were within the threshold limit values of the Chinese Control Standards for Pollutants in Sludge from Agriculture Use (GB4284-84). Four indices were used to assess the pollution and the ecological risk of heavy metals. By the mean values of the geoaccumulation index (I geo ), heavy metals were ranked in the following order: Cd > Zn > Cu > As > Cr > Ni > Pb. The values showed that the pollution of Zn in station 3 and Cd in station 1, 2, 3, 4, 8 and 9 were heavily; Cu in station 8 and 9, Zn in station 1, 2, 4, 8 and 9 and Cd in station 5 and 7 were moderately to heavily, and the accumulation of other heavy metals were not significant. The single-factor pollution index (PI) suggested that none of the stations had heavy metals contamination, except for Cu in station 9, Zn in station 3 and 8, and Cd in station 1 and 9, which were at a moderate level. According to the results of the Nemerow’s synthetic pollution index (PN), sewage sludge from all stations was safe for land use with respect to heavy metals contamination, except for stations 3, 8 and 9, which were at the warning line. The monomial potential ecological risk coefficient (Eri) revealed that heavy metals ecological risks in most stations were low. However, station 9 had a moderate risk for Cu; station 6 had a moderate risk, stations 5 and 7 had high risk, other stations had very high risk for Cd. According to the results of the potential ecological risk index (RI), station 1, 8 and 9 had high risk; station 2, 3, 4, 5 and 7 had a moderate risk, and station 6 had a low risk. The preliminary results indicated that the potential risk of land exposure to heavy metals in sewage sludge was relatively low, with Zn and Cd as the main contributor to the ecological risk for the applying of sewage sludge on land. Additionally, stations 3, 8 and 9 require more attention regarding the land applications related to heavy metals pollution.

Keywords: heavy metals; sewage sludge; ecological risk; geoaccumulation index; single-factor pollution index; Nemerow’s synthetic pollution index; monomial potential ecological risk coefficient; potential ecological risk index (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2017
References: View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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