Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
Shenzhen Water (Group) Co., Ltd, Shenzhen, Guangdong, China.
Chemosphere. 2021 Nov;283:131158. doi: 10.1016/j.chemosphere.2021.131158. Epub 2021 Jun 10.
Azo dye is the most versatile class of dyes used in the textile industry. Although the sulfidogenic process shows superiority in the removal of azo dye, the role of biogenic sulfide produced by sulfate-reducing bacteria (SRB) in the decolorization of azo dye is unclear. This study explored the mechanism of biogenic sulfide for removal of a model azo dye (Direct Red 81 (DR 81)) through biotic and abiotic batch tests with analysis of intermediates of the azo dye degradation. The results showed that biogenic sulfide produced from sulfate reduction directly cleaved two groups of azo bond (-NN-), thereby achieving decolorization. Moreover, the decolorization rate was enhanced by nearly 3-fold (up to 42 ± 1 mg/L-hr; removal efficiency > 99%) by adding an external carbon source or elevating the initial azo dye concentration. This study showed that biogenic sulfide plays an essential role in azo dye decolorization and provides a new avenue for the potential application of biogenic sulfide from the sulfidogenic system for the treatment of azo dye-laden wastewater.
偶氮染料是纺织工业中应用最广泛的一类染料。尽管硫酸盐还原菌（SRB）产生的生物硫化物在偶氮染料的去除方面表现出优越性，但生物硫化物在偶氮染料脱色中的作用尚不清楚。本研究通过生物和非生物批量试验，分析偶氮染料降解的中间产物，探讨了生物硫化物去除模型偶氮染料（直接红 81（DR 81））的机制。结果表明，硫酸盐还原产生的生物硫化物直接切断了偶氮键（-NN-）的两组，从而实现了脱色。此外，通过添加外部碳源或提高初始偶氮染料浓度，脱色率提高了近 3 倍（最高可达 42±1mg/L-hr；去除效率>99%）。本研究表明，生物硫化物在偶氮染料脱色中起着重要作用，为利用硫化物生成系统中的生物硫化物处理偶氮染料废水提供了新途径。
