Anaerobic structured‐bed reactor for azo dye decolorization in the presence of sulfate ions

Abstract

Abstract BACKGROUND Textile wastewater is known for its polluting potential and toxicity. Biological, affordable treatments are especially desirable in developing countries to fulfill legal and ecological demands during its treatment. RESULTS The performance of an anaerobic structured‐bed reactor (AnSTBR) treating synthetic textile wastewater containing Direct Black 22 azo dye (DB22; 0.06 mmol L –1 ) and sulfate ions (200 mg L −1 ) was evaluated. The reactor hydraulic retention time (HRT) was 24 h and ethanol was used as the electron donor (1000 mgCOD L −1 ). The AnSTBR achieved an average decolorization efficiency of 68 ± 5%, chemical oxygen demand (COD) efficiency of 77.7 ± 9.2% and sulfate removal of 77.3 ± 5.2%. Toxicity tests showed lower toxicity of the treated effluent to Ceriodaphnia dubia . Despite that, the AnSTBR effluent was still highly toxic to mammalian cells. The metabarcoding technique of the 16S rRNA gene sequencing revealed a consistent community of sulfate‐reducing and azo‐degrading bacteria. CONCLUSION Metagenomic data revealed a promising development of the inoculum in the AnSTB structure. The AnSTB reactor configuration may be a promising alternative for DB22 dye removal from textile wastewater containing sulfate. © 2021 Society of Chemical Industry