Continuous-mode acclimation and operation of lignocellulosic sulfate-reducing bioreactors for enhanced metal immobilization from acidic mining-influenced water

Evelyn M. Miranda, Carli Severson, Jeffrey K. Reep, Daniel Hood, Shane Hansen, Leonard Santisteban, Nasser Hamdan, Anca G. Delgado

Research output: Contribution to journalArticlepeer-review

Abstract

Lignocellulosic sulfate-reducing bioreactors are an inexpensive passive approach for treatment of mining-influenced water (MIW). Typically, microbial community acclimation to MIW involves bioreactor batch-mode operation to initiate lignocellulose hydrolysis and fermentation and provide electron donors for sulfate-reducing bacteria. However, batch-mode operation could significantly prolong bioreactor start-up times (up to several months) and select for slow-growing microorganisms. In this study we assessed the feasibility of bioreactor continuous-mode acclimation to MIW (pH 2.5, 6.5 mM SO42−, 18 metal(loid)s) as an alternate start-up method. Results showed that bioreactors with spent brewing grains and sugarcane bagasse achieved acclimation in continuous mode at hydraulic retention times (HRTs) of 7–12-d within 16–22 days. During continuous-mode acclimation, extensive SO42− reduction (80 ± 20% –91 ± 3%) and > 98% metal(loid) removal was observed. Operation at a 3-d HRT further yielded a metal(loid) removal of 97.5 ± 1.3 –98.8 ± 0.9% until the end of operation. Sulfate-reducing microorganisms were detected closer to the influent in the spent brewing grains bioreactors, and closer to the effluent in the sugarcane bagasse bioreactors, giving insight as to where SO42− reduction was occurring. Results strongly support that a careful selection of lignocellulose and bioreactor operating parameters can bypass typical batch-mode acclimation, shortening bioreactor start-up times and promoting effective MIW metal(loid) immobilization and treatment.

Original languageEnglish (US)
Article number128054
JournalJournal of Hazardous Materials
Volume425
DOIs
StatePublished - Mar 5 2022
Externally publishedYes

Keywords

  • Acid mine drainage
  • Bioremediation
  • Lignocellulose
  • Spent brewing grains
  • Sugarcane bagasse
  • Sulfate-reducing bacteria

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis

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