Degradation of reactive black 5 dye by aerobic granular sludge

Abstract

In order to explore the removal effect and degradation mechanism of the reactive black 5 dye in the aerobic granular sludge system. a constant working volume sequential batch reactor (SBR) was set up to cultivate aerobic granular sludge under alternative anaerobic and aerobic operating condition to treat synthetic azo dye wastewater. The removal efficiency of COD, NH4+-N and PO43--P and the removal load of reactive black 5 were measured in the SBR system, and the mechanism of azo dyes was further explored by high through-put sequencing of 16S rRNA gene. The results showed that the SBR system had a good effect in removing pollutants, the removal rates of COD, NH4+-N and PO43--P reached 90%, 95% and above 95% at the end of culture period, and the removal of azo dye maintained around 0.005 kg·(kg·d)-1. The azo double bond of the reactive black 5 dye mainly broke at the anaerobic stage, and the intermediates containing benzene and naphthalene rings were degraded at the aerobic stage. High-throughput sequencing analysis of the 16S rRNA gene showed that azo dye increased the nitrogen load of the SBR system, thus increasing the abundance of nitrifying bacteria and the bacteria which had the function of denitrifying or degrading aromatic substances genera such as Paracoccus, Azoarcus and Thauera.

Keywords

• aerobic granular sludge
• reactive black 5 dye
• anaerobic condition
• degradation mechanism
• bacteria community structure