Extracellular polymeric substances excreted by anammox sludge act as a barrier for As(III) invasion: Binding property and interaction mechanism

The arsenic in livestock wastewater would induce adverse impact on the biological treatment technology such as anaerobic ammonium oxidation (anammox) process. Extracellular polymeric substances (EPS) play an important role in resisting such toxicity. Unfortunately, the role of EPS in protecting anammox from As(III) and the mechanisms underlying the protection still remains unclear. This work comprehensively evaluated the acute toxicity of arsenic on anammox sludge and investigated the binding property and interaction mechanism. The results revealed that the half maximal inhibitory concentration (IC50) of As(III) on anammox sludge was estimated to be 408 mg L-1, which decreased to 41.97 mg L-1 when EPS was exfoliated. Complexation and hydrophobic interactions were the leading forces in preventing arsenic invasion. Protein was the main component that complexes with As(III), and O-H, -NH, -C=O were binding sites. The response sequence of organic component in EPS to As(III) was ordered as hydrocarbons-proteins-polysaccharides-aliphatic amines. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Arsenic has a negative impact on anammox treatment technology, while extracellular polymeric substances (EPS) play an important role in resisting this toxicity. In this study, it was found that proteins are the main component in EPS that forms complexes with arsenic, and complexation and hydrophobic interactions are the main forces preventing arsenic invasion.