Passive Treatment of Acid Mine Drainage Integrated with Carbon Dioxide Removal by Enhanced Rock Weathering in Acid Mine Drainage

[Geoengineering News]

https://www.imwa.info/docs/imwa_2025/IMWA2025_Nakamura_696.pdf

Authors

Fugo Nakamura, Hkaung Htut San, Hajime Iwaki, Monthicha Rawangphai, Naomi

Kitagawa, Shinichiro Morimoto, Takao Nakagaki, Tsutomu Sato

Abstract

Interest is growing in Enhanced Rock Weathering (ERW) as a Carbon Dioxide

Removal (CDR) strategy already applied to terrestrial and marine environments.

Research shows that most silicate minerals dissolve several orders of magnitude

faster under strongly acidic conditions like those found in acid mine drainage

(AMD). An advantage of this approach is that silicate mineral dissolution from basalt

increases AMD pH, potentially enabling passive treatment systems. To investigate

both CDR potential and passive treatment possibilities of basalt-based ERW in

AMD, we conducted one-dimensional reactive-transport modeling (1D-RTM)

as a case study using the Amemasu River downstream from the abandoned

Shojin mine. Using 1D-RTM, we estimated annual basalt weathering rates, CDR

potential, and secondary schwertmannite formation. Life cycle assessment (LCA)

and techno-economic evaluation (TEA) were then performed to determine net

CDR and economic feasibility. We applied a surface complexation model (SCM) to

evaluate contaminant adsorption by schwertmannite precipitates. Results show that ERW in AMD provides sufficient net CDR to be economically viable. Moreover,

schwertmannite formation efficiently removes arsenic through adsorption while

simultaneously releasing protons that maintain the acidic conditions necessary

for enhanced mineral weathering. These dual benefits—carbon sequestration and

contaminant removal—offer substantial economic incentives for treating AMD

sites, particularly those contaminated with arsenic, iron, and sulfate. AMD treatment

with limestone can be a major challenge to carbon neutrality in terms of economic

burden and emissions. Our findings suggest the possibility of replacement of some

active AMD treatment with limestone. 

Source: IMWA