Title: Microbially induced calcite precipitation for stabilisation and solidification of copper loaded biochar

Authors: Misbah Bashir; Kala Venkata Uday; Ajit P. Annachhatre

Addresses: Indian Institute of Technology, Mandi, Himachal Pradesh, 175005, India ' Indian Institute of Technology, Mandi, Himachal Pradesh, 175005, India ' Indian Institute of Technology, Mandi, Himachal Pradesh, 175005, India

Abstract: This research highlights stabilisation and solidification (s/s) of copper loaded biochar with grade F fly ash and bentonite through microbially induced calcite precipitation (MICP) induced by S. pasteurii as urease producing bacteria. MICP matrix of 90% fly ash and 10% bentonite yielded the highest unconfined compressive strength (UCS) of 253 kPa at curing time of 28 days. Subsequent s/s experiments were carried out with this optimal mixture with the addition of copper loaded biochar ranging from 0% to 2.5% and UCS was always higher than 150 kPa for curing time of 28 days. Strong alkaline nature of fly ash and bentonite induced calcification due to the activity of S. pasteurii and eventually facilitated immobilisation of copper into s/s matrix. Results from toxicity characteristics leaching procedure (TCLP) revealed that up to 2.5% copper loaded biochar in optimised s/s matrix had 100% stabilisation of copper.

Keywords: microbially induced calcite precipitation; MICP; fly ash; bentonite; S. pasteurii; s/s; immobilisation; calcification; unconfined compressive strength; UCS; toxicity characteristics leaching procedure; TCLP; copper loaded biochar.

DOI: 10.1504/IJEWM.2026.151368

International Journal of Environment and Waste Management, 2026 Vol.39 No.1, pp.84 - 102

Accepted: 09 Nov 2024
Published online: 26 Jan 2026 *

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