Abstract
Sewage sludge as waste of the wastewater treatment process contains toxic substances, and its conversion into sludge biochar-based catalysts is a promising strategy that merges the merits of waste reutilization and environmental cleanup. This study aims to systematically recapitulate the published articles on the development of sludge biochar-based catalysts in different advanced oxidation processes of wastewater, including sulfate-based system, Fenton-like systems, photocatalysis, and ozonation systems. Due to abundant functional groups, metal phases and unique structures, sludge biochar-based catalysts exhibit excellent catalytic behavior for decontamination in advanced oxidation systems. In particular, the combination of sludge and pollutant dopants manifests a synergistic effect. The catalytic mechanisms of as-prepared catalysts in these systems are also investigated. Furthermore, initial solution pH, catalyst dosage, reaction temperature, and coexisting anions have a vital role in advanced oxidation processes, and these parameters are systematically summarized. In summary, this study could provide relatively comprehensive and up-to-date messages for the application of sludge biochar-based catalysts in the advanced oxidation processes of wastewater treatment.
Highlights
With the rapid development of industrialization, urbanization and population, water pollution has become an increasingly concerning issue worldwide [1]
Chen et al [22] employed catalytic ozonation involving petroleum waste sludge biochar catalyst (SBC) for the treatment of refinery wastewater and found that the total number of polar contaminants was reduced by 39.6% (1379 vs. 2285) through OH-mediated oxidation, resulting in enhancing TOC removal efficiency compared to ozonation
This review shows that the conversion of sludge into sludge biocharbased catalysts is a promising strategy that merges the merits of waste reutilization and environmental cleanup
Summary
With the rapid development of industrialization, urbanization and population, water pollution has become an increasingly concerning issue worldwide [1]. Biological treatments were applied in the wastewater treatments worldwide and a significant amount of waste sludge was produced [2]. The annual output of sludge reached 60–90 million tons in 2020 in. Since sludge contains many toxic substances (such as organic compounds and heavy metals), many conventional sludge disposal methods cause environmental risks; counting landfill, ocean dumping, agriculture usage and incineration are all limited by potential risks [4,5]. The cost of standardized disposal for the sludge is high, accounting for 30–60% of the total operation costs of wastewater treatment plants [6]. The safe treatment and disposal of sewage sludge pose a great challenge to environmental development
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