The potential of alkaline tolerant microbial consortia for textile wastewater treatment under integrated anaerobic/aerobic conditions: Performance evaluation and microbial community analysis

Abstract

Sequential anaerobic/aerobic (A/O) treatment conditions for textile wastewater (WW) are more effective than conventional biological treatment. Anaerobic treatment is essential because anaerobic microbes can first break down complex and recalcitrant compounds, which are difficult to degrade under aerobic conditions. The simpler, more degradable compounds are then further broken down by aerobic microbes. This study aimed to evaluate the performance of a sequential A/O treatment process using a pilot-scale reactor to treat real textile WW and to characterize reactor and inoculum microbial community structures. The reactors were inoculated with microbial consortia originating from a diverse alkaliphilic soda lake in the Ethiopian Rift Valley. The WW test parameters were used to evaluate the performance of the treatment process. At steady state, the removal efficiencies were 97 % for dye, 86 % for Chemical Oxygen Demand (COD), and 93 % for Total Kjeldahl Nitrogen (TKN). Amplicon sequencing revealed that Firmicutes , Proteobacteria, and Actinobacteria were the dominant phyla in all the samples. Uncategorized microorganisms, followed by Alkalibacterium, Bifidobacterium, and Clostridium were the most abundant taxon in all the samples. The microbial community detected during the treatment process was not abundant in the inoculum originating from Lake Chitu, suggesting that the communities likely originated from textile WW. The textile WW treated with the integrated A/O process effectively degraded dyes, and the inoculated microbes demonstrated resistance to the toxic chemical composition of the WW. The integrated treatment process, along with the alkaliphilic microbial consortia, has proven to be practical for treating textile WW, offering valuable insights for field-scale applications. • The microbial consortia removed dyes (97%), COD (86%), and TKN (93%). • The sequential aerobic reactor was found to enhance COD and TKN removal. • Firmicutes and Actinobacteria were the dominant phyla detected throughout the treatment. • Alkalibacterium, Halomonas, Bifidobacterium , and Clostridium were abundantly detected as dye-degrading bacteria. • These environments were found to be suitable sources of microbes for treating textile dye wastewater.