Toward Green and Efficient Pretreatment for Waste Activated Sludge Resourcization and Valorization: A Review

Kai Chen; Bizhen Zeng; Zhuo Li; Long Chen; Lan Yang; Hongtao Zhu

doi:10.1016/j.envres.2025.122227

Toward Green and Efficient Pretreatment for Waste Activated Sludge Resourcization and Valorization: A Review

Environ Res. 2025 Jun 25:122227. doi: 10.1016/j.envres.2025.122227. Online ahead of print.

Authors

Kai Chen¹, Bizhen Zeng¹, Zhuo Li², Long Chen¹, Lan Yang¹, Hongtao Zhu³

Affiliations

¹ Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China.
² Offshore environmental technology & services limited, Beijing 100020, China.
³ Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China. Electronic address: zhuhongtao@bjfu.edu.cn.

PMID: 40578742
DOI: 10.1016/j.envres.2025.122227

Abstract

The resourcization and valorization of waste activated sludge through anaerobic digestion are vital for promoting sustainability. However, the majority of organic matter in sludge is hindered from release by extracellular polymeric substances and plasma membranes, requiring pretreatment to disrupt these structures and enhance effective bioconversion. More than 3,000 literature studies on pretreatment technologies have been conducted over the past five years, but there remains a clear gap in the comprehensive understanding of state-of-the-art sludge pretreatment methods. This review presents recent advancements in sludge pretreatment, with a focus on the emerging application of radio frequency technology. We examine the principles and effectiveness of various pretreatment methods, while critically assessing their performance and energy efficiency. This review will enhance the understanding of pretreatment mechanisms, fill the gaps in Frontier technologies, and inspire future developments toward more sustainable sludge management protocols.

Keywords: Extracellular polymeric substances; Microbial cell; Sludge pretreatment; Sustainability; Waste activated sludge.

Publication types

Review