Research progress in improving sludge dewaterability: sludge characteristics, chemical conditioning and influencing factors

Jiachen Hou; Chen Hong; Wei Ling; Jiashuo Hu; Weibo Feng; Yi Xing; Yijie Wang; Chengwang Zhao; Lihui Feng

doi:10.1016/j.jenvman.2023.119863

Research progress in improving sludge dewaterability: sludge characteristics, chemical conditioning and influencing factors

J Environ Manage. 2024 Feb:351:119863. doi: 10.1016/j.jenvman.2023.119863. Epub 2023 Dec 22.

Authors

Jiachen Hou¹, Chen Hong², Wei Ling¹, Jiashuo Hu¹, Weibo Feng¹, Yi Xing³, Yijie Wang¹, Chengwang Zhao¹, Lihui Feng¹

Affiliations

¹ School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China.
² School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, Beijing, 100083, China. Electronic address: hongchen@ustb.edu.com.
³ School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, Beijing, 100083, China.

PMID: 38141343
DOI: 10.1016/j.jenvman.2023.119863

Abstract

Sludge from wastewater treatment processes with high water content and large volume has become an inevitable issue in environmental management. Due to the challenging dewatering properties of sludge, current mechanical dewatering methods are no longer sufficient to meet the escalating water content standards of sludge. This paper summarizes the characteristics of various sludge and raises reasons for the their dewaterability differences. Affected by extracellular polymeric substances, biological sludge is hydrophilic and negatively charged, which limits the dewatering degree. The rheological properties, flocs, ionic composition, and solid phase concentration of the sludge also influence the dewatering to some extent. For these factors, the chemical conditioning measures with simple operation and excellent effect improve its dewaterability, which mainly include flocculation/coagulation, acid/alkali treatment, advanced oxidation, surfactant treatment and combined treatment. There is a growing necessity to explore the development of new chemical conditioning agents, even though traditional agents continue to remain widely used. However, the development of these new agents should prioritize finding a balance between various factors such as efficiency, effectiveness, ease of operation, environmental safety, and cost-effectiveness. Electrochemical dewatering enhances solid-liquid separation, and its coupling with chemical conditioning is also an excellent means to further reduce water content. In addition, the improvement of press filter is an effective way, which is influenced by pressure, processing time, sludge cake thickness and pore structure, filter media etc. In general, it is essential to develop new conditioning agents and enhance mechanical filtration press technology based on a thorough understanding of various sludge properties. Concurrently, an in-depth study of the principles of mechanical pressure filtration will contribute to establishing a theoretical foundation for effective deep sludge dewatering and propel further advancements in this field.

Keywords: Chemical conditioning; Dewatering mechanism; Mechanical dewatering; Sewage sludge.

Publication types

Review

MeSH terms

Filtration
Flocculation
Pressure
Sewage* / chemistry
Waste Disposal, Fluid / methods
Water* / chemistry

Substances

Sewage
Water