Nature-based solution to eliminate cyanotoxins in water using biologically enhanced biochar.

Moore, Jane; Jayakumar, Anjali; Soldatou, Sylvia; Mašek, Ondřej; Lawton, Linda A.; Edwards, Christine

Abstract

Climate change and high eutrophication levels of freshwater sources are increasing the occurrence and intensity of toxic cyanobacterial blooms in drinking water supplies. Conventional water treatment struggles to eliminate cyanobacteria/cyanotoxins and expensive tertiary treatments are needed. To address this, we have designed a sustainable, nature-based solution using biochar derived from waste coconut shells. This biochar provides a low-cost porous support for immobilising microbial communities forming biologically enhanced biochar (BEB). Highly toxic microcystin-LR (MC-LR) was used to influence microbial colonization of the biochar by natural lake water microbiome. Over 11 months, BEBs were exposed to microcystins, cyanobacterial extracts and live cyanobacterial cells, always resulting in rapid elimination of toxins and even a 1.6-1.9 log reduction in cyanobacterial cell numbers. After 48 hours incubation with our BEBs, the MC-LR concentrations dropped below the detection limit of 0.1 ng/ml. The accelerated degradation of cyanotoxins was attributed to enhanced species diversity and microcystin-degrading microbes colonising the biochar. To ensure scalability, we evaluated BEBs produced through batch-scale and continuous-scale pyrolysis, while also guaranteeing safety by maintaining toxic impurities in biochar within acceptable limits and monitoring degradation by-products. This study serves as a proof-of-concept for a sustainable, scalable and safe nature-based solution for combating toxic algal blooms.

Citation

MOORE, J., JAYAKUMAR, A., SOLDATOU, S., MAŠEK, O., LAWTON, L.A. and EDWARDS, C. 2023. Nature-based solution to eliminate cyanotoxins in water using biologically enhanced biochar. Environmental science and technology [online], 57(43), pages 16372-16385. Available from: https://doi.org/10.1021/acs.est.3c05298

• Journal Article Type: Article
• Acceptance Date: Oct 5, 2023
• Online Publication Date: Oct 19, 2023
• Publication Date: Oct 31, 2023
• Deposit Date: Oct 18, 2023
• Publicly Available Date: Oct 18, 2023
• Journal: Environmental science and technology
• Print ISSN: 0013-936X
• Electronic ISSN: 1520-5851
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 57
• Issue: 43
• Pages: 16372-16385
• DOI: https://doi.org/10.1021/acs.est.3c05298
• Keywords: Cyanotoxins; Water treatment; Biological water treatment; Eutrophication; Waste valorisation; Microcystins
• Public URL: https://rgu-repository.worktribe.com/output/2098666