Feasibility assessment of the production of bioethanol from lignocellulosic biomass pretreated with acid mine drainage (AMD)

A techno-economic evaluation of a lignocellulosic bioethanol facility that uses acid mine drainage for the pre-treatment of weeping love grass (Eragrostis curvula) was performed. Both separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) reactor configurations were evaluated. Results were compared to an evaluation of the same process with biomass pre-treated with dilute H2SO4. Capital and operating costs were estimated and a simple economic evaluation was conducted. It was found that all scenarios made a loss except for biomass pre-treated with H2SO4 in the SHF reactor configuration, although the high capital cost resulted in a payback period of 80.7 years, which is unfeasible. SHF was found to produce more ethanol at a lower capital cost than SSF, indicating that it is more economically feasible. Incorporating the remediation of AMD into a simultaneous process could help improve process economics. It is thus recommended that a techno-economic evaluation be conducted on a process that produces bioethanol through SHF and simultaneously remediates AMD.