Application of biochar on soil bioelectrochemical remediation: behind roles, progress, and potential

Abstract

Bioelectrochemical systems (BESs) that combine electrochemistry with biological methods have gained attention in the remediation of polluted environments, including wastewater, sludge, sediments, and soils. The most attractive advantage of BESs is that the solid electrode is used as an inexhaustible electron acceptor or donor, and biocurrent directly converted from organics can afford the reaction energy of contaminant breakdown, crossing the internal energy barrier of endothermic degradation, which achieves a continuous biodegradation process without the simultaneous use of exogenetic chemicals and bioelectricity recovery. However, soil BESs are hindered by expensive electrode materials, difficult pollutant and electron transfer, low microbial competitive activity, and biocompatibility in contamination remediation. Fortunately, introducing biochar into soil BESs could reveal a high potential in addressing these BES inadequacies. The characteristics of biochar, e.g., conductivity, transferability, high specific surface area, high porosity, large functional groups, and biocompatibility, can improve the performance of soil BESs. In fact, biochar not only carries electrons but also transfers nutrients, pollutants, and even bacteria by facilitating transmission in the bioelectric field of BESs. Consequently, the abilities of biochar make for better functionality of BESs. This review collates information on the roles, application, and progress of biochar in soil BESs, and future prospects are given. It is beneficial for environmental researchers and engineers to extend BES application in environmental remediation and to assist the progress of carbon sequestration and emission reduction based on the inertia of biochar and the blocking of electron flow to form methane.

Graphical Abstract

Highlights

• A feature comparison between BES and conventional techniques was made.

• Biochar characteristics match the deficiencies of bioelectrochemical remediation.

• Behind roles of biochar in the contamination remediation were summarized.

• Application potential and direction of biochar in BES were emphasized.

Keywords:

• Biochar
• characteristics
• bioelectrochemical system
• soil remediation
• mass transfer

Acknowledgments

The authors thank the financial support from the National Natural Science Foundation of China [Nos. 41977133, 41601536, and 41807143], the Natural Science Foundation of Tianjin [Nos. 20JCYBJC01590 and 16JCQNJC08800] and the Basic Frontier Project and Key Projects at the Institute of Innovation Engineering of Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs.

Disclosure statement

No potential conflict of interest was reported by the author(s).