Reviewing Improved Anaerobic Digestion by Combined Pre-Treatment of Waste-Activated Sludge (WAS)

Miao Yang, Margot Vander Elst, Ilse Smets, Huili Zhang, Shuo Li, Jan Baeyens () and Yimin Deng ()
Additional contact information
Miao Yang: Beijing Advanced Innovation Centre for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
Margot Vander Elst: Chemical Engineering Department, KU Leuven, 3001 Leuven, Belgium
Ilse Smets: Chemical Engineering Department, KU Leuven, 3001 Leuven, Belgium
Huili Zhang: School of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
Shuo Li: School of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
Jan Baeyens: Beijing Advanced Innovation Centre for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
Yimin Deng: School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100811, China

Sustainability, 2024, vol. 16, issue 15, 1-18

Abstract: The anaerobic digestion of wastewater treatment sludge (WAS) produces a “green” biogas while reducing the amount of residual sludge. To increase the yield of biogas, several individual or combined pre-treatment methods of WAS can be used. These pre-treatment methods substantially reduce the amount of volatile suspended solids (VSSs) and their associated total chemical oxygen demand (TCOD). Pre-treating the sludge will increase the methane yield by 15 to 30%. Although the individual methods have been dealt with in research and large-scale operations, the combined (hybrid) methods have not previously been reviewed. Here, different hybrid treatment methods are reviewed, including (1) thermochemical hydrolysis pre-treatment, using an alkaline or acid addition to enhance solubilization of the sludge cells and increase biogas production; (2) alkaline and high-pressure homogenizer pre-treatment, combining a chemical and mechanical treatment; (3) alkaline and ultrasound pre-treatment, capable of solubilizing organic sludge compounds by different mechanisms, such as the fast and effective ultrasound disruption of cells and the increasing effect of the alkaline (NaOH) treatment; (4) combined alkaline and microwave pre-treatment, which enhances sludge solubilization by at least 20% in comparison with the performance of each separate process; (5) microwave (MW) and peroxidation pre-treatment of WAS suspended solids (SSs), which are quickly (<5 min) disintegrated by MW irradiation at 80 °C; (6) ultrasound and peroxidation pre-treatment, with ozone and peroxides as powerful oxidizing agents; and (7) pulsed electric field (PEF) pretreatment. All literature findings are assessed, discussing relevant operation conditions and the results achieved.

Keywords: review; anaerobic digestion; waste-activated sludge; pre-treatment methods; increased biogas production (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2024
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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