Abstract
Acid mine drainage (AMD) generated by mining and metallurgical industries creates serious environmental problems. Treatment of AMD using sulfate-reducing bioreactors with rice bran is promising; however, this approach is limited by the biofilm formation at the top of the bioreactor, which can cause a significant reduction in water permeability. To assess biofilm microbiomes, both 16S and 18S rRNA gene amplicon sequencing of 10 biofilm samples were performed. Although the top five dominant microbial operational taxonomic units (OTUs) in the respective biofilms were diverse, common bacterial OTUs were found within the biofilms from the same bioreactor. In prokaryotes, OTUs related to Acinetobacter junii and Pseudomonas palleroniana made up the dominant species. As for eukaryotes, OTUs associated with Mortierella sp. and Chytriomyces sp. were detected, especially from acidic biofilm samples. The addition of anti-biofilm and anti-microbial reagents to the bioreactors may restrict biofilm formation. However, considering implementation costs and environmental influences, the operational management of bioreactors should also be considered; e.g., change of substrate from rice bran to low molecular weight organic compounds under acidic conditions.
