(2026) Journal of Water Process Engineering_Comparative evaluation of biochar, bone char, and conventional sorbents for arsenic removal from water: Performance and life-cycle carbon assessment

Biswas P.P.; Chen W.-H.; Chang J.-S.; Kwon E.E.; Lin K.-Y.A.; Pétrissans M.; Pétrissans A.

(Elsevier Ltd) Journal of Water Process Engineering ISSN: 22147144 Vol.89 Issue. Article No.110338 DOI: 10.1016/j.jwpe.2026.110338

Arsenic contamination of water poses a significant environmental and public health challenge, necessitating sustainable, low-carbon treatment technologies. This study aims to evaluate the carbon credit potential and arsenic removal performance of microwave-assisted (MW) biochar and MW bone char relative to conventional sorbents. Carbon emissions are quantified using life cycle assessment, and carbon sequestration is determined by elemental carbon analysis. Carbon credits are calculated for treating 1000 L of wastewater (0.3 to 0.01 mg·L⁻¹). MW biochar achieves the only positive carbon credit (+0.0002 t CO₂-eq·m⁻³) despite low arsenic sorption (0.78 mg·g⁻¹), while MW bone char shows superior arsenic removal (2.78 mg·g⁻¹) but incurs a net carbon debt (−0.00006 t CO₂-eq·m⁻³). This trade-off reveals that higher sorption capacity does not guarantee lower carbon impact. MW biochar sequesters 1.7967 kg CO₂-eq per kg versus 1.0882 kg CO₂-eq emitted, making it the only carbon-negative option. These findings demonstrate that integrating carbon sequestration with remediation performance can guide the selection of low-carbon sorbents for sustainable water treatment. © 2026 Elsevier Ltd.

The authors gratefully acknowledge financial support from the National Science and Technology Council, Taiwan, R.O.C., under the contracts NSTC 114-2221-E-029-006-, NSTC 114-2218-E-006-013-, and NSTC 115-2923-E-006-006-MY3 for this study. This research is also partly supported by the Higher Education Sprout Project, Ministry of Education, to the Headquarters of University Advancement at National Cheng Kung University (NCKU). The authors gratefully acknowledge the use of EM000700 and XRD005100 of NSTC 114-2740-M-006-001, belonging to the Core Facility Center of National Cheng Kung University.