ORIGINAL RESEARCH article
Front. Environ. Sci.
Sec. Toxicology, Pollution and the Environment
This article is part of the Research TopicSustainable Solutions for Soil Contamination and Sludge Management: Advances in Geoenvironmental EngineeringView all 5 articles
Spatio-temporal Distribution and Comprehensive Risk Assessment of Heavy Metals in Sewage Sludge from Wastewater Treatment Plants in the Dianchi Lake Basin
Provisionally accepted
- 1Kunming Urban Drainage and Sewerage Monitoring Station, Kunming, China
- 2Key Laboratory of Ethnomedicine Resource Chemistry of the Ministry of Education, College of Ethnic Medicine, Yunnan Minzu University, Kunming, China
- 3Kunming Customs Technology Center, Kunming, China
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Heavy metals (HMs) in sewage sludge from municipal wastewater treatment plants (WWTPs) represent a latent threat to lake ecosystems. Accurately characterizing their pollution profiles and associated risks is a universal imperative for ecological conservation in cities situated within globally sensitive lake basins. Focusing on 27 WWTPs across the Dianchi Lake Basin, this study collected 335 sludge samples over 12 consecutive quarters. Leveraging multi-dimensional comprehensive assessment approaches, we analyzed the pollution characteristics, risk levels, and sources of HMs— aiming to deliver scientific evidence and a scalable framework for safe sewage sludge management in plateau lake basins. Key findings are as follows: ① Arsenic (As) emerged as the dominant pollutant with a high detection rate, with 20 exceedance events documented across 8 WWTPs. Cadmium (Cd) concentrations ranged from 19 to 259 mg/kg; its pollution risk was elevated in the dry season relative to the wet season, exhibiting a distinct spatial distribution pattern of "higher in the northeast and lower in the southwest". ② Ecological risk assessment demonstrated that Cd and mercury (Hg) accounted for 55.4% and 34.6% of the total ecological risk, respectively, functioning as the core pollutants driving HMs-associated ecological risks in the basin's sewage sludge. ③ Source apportionment confirmed that metal processing and smelting industries constituted the primary source of HMs in sewage sludge, contributing 41.8% of the total load. ④ Comparative analysis of treatment processes revealed that the membrane bioreactor (MBR) and intermittent cyclic extended aeration system (ICEAS) resulted in the highest HMs accumulation in sewage sludge, with comprehensive pollution indices of 0.280 and 0.250, respectively.
Keywords: heavy metals, Multi-model risk assessment, sewage sludge, SOURCE APPORTIONMENT, Spatial-temporal distribution, Wastewater treatment plant
Received: 31 Oct 2025; Accepted: 20 Jan 2026.
Copyright: © 2026 Wei, Ma, Lü, He, Li, Zuo, Liu and Zhang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Jiao Ma
Xu Zhang
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