Enhancing microbial salt tolerance through low-voltage stimulation for improved p-chloronitrobenzene (p-CNB) removal in high-salinity wastewater

Long Chen; Li-Ting Zhou; Yang-Cheng Ding; Di Wu; Hua-Jun Feng

doi:10.1016/j.scitotenv.2023.167164

Enhancing microbial salt tolerance through low-voltage stimulation for improved p-chloronitrobenzene (p-CNB) removal in high-salinity wastewater

Sci Total Environ. 2023 Dec 20:905:167164. doi: 10.1016/j.scitotenv.2023.167164. Epub 2023 Sep 18.

Authors

Long Chen¹, Li-Ting Zhou¹, Yang-Cheng Ding², Di Wu³, Hua-Jun Feng⁴

Affiliations

¹ School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, Zhejiang, China; International Science and Technology Cooperation Platform for Low-Carbon Recycling of Waste and Green Development, Zhejiang Gongshang University, Hangzhou 310018, Zhejiang, China.
² School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, Zhejiang, China; International Science and Technology Cooperation Platform for Low-Carbon Recycling of Waste and Green Development, Zhejiang Gongshang University, Hangzhou 310018, Zhejiang, China; College of Environment and Resources, Zhejiang A&F University, Hangzhou 310018, Zhejiang, China.
³ Faculty of Bioengineering, Ghent University, Ghent 9000, Belgium.
⁴ School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, Zhejiang, China; International Science and Technology Cooperation Platform for Low-Carbon Recycling of Waste and Green Development, Zhejiang Gongshang University, Hangzhou 310018, Zhejiang, China; College of Environment and Resources, Zhejiang A&F University, Hangzhou 310018, Zhejiang, China. Electronic address: fenghuajun@zjgsu.edu.cn.

PMID: 37730069
DOI: 10.1016/j.scitotenv.2023.167164

Abstract

As an important raw material for the synthesis of chemical and pharmaceutical, hazardous carcinogen p-chloronitrobenzene (p-CNB) has been widely found in high-salinity wastewater which need to be treated carefully. Due to the high-salinity shock on microorganisms, conventional microbial treatment technologies usually show poor effluent quality. This study initially investigated the p-CNB removal performance of microorganisms stimulated by 1.2 V low-voltage in high-salinity wastewater under facultative anaerobic conditions and further revealed the enhanced mechanisms. The results showed that the p-CNB removal kinetic parameter k_p-CNB in the electrostimulating microorganism reactor (EMR) increased by 104.37 % to 155.30 % compared to the microorganism reactor (MR) as the control group under the varying salinities (0-45 g/L NaCl). The secretion of extracellular polymeric substances (EPS) in halotolerant microorganisms mainly enhanced by 1.2 V voltage stimulation ranging from 0 g/L NaCl to 30 g/L NaCl. Protein concentration ratio of EMR to MR in loosely bound EPS achieved maximum value of 1.77 at the salinity of 15 g/L NaCl, and the same ratio in tightly bound EPS also peaked at 1.39 under the salinity of 30 g/L NaCl. At the salinity of 45 g/L NaCl, 1.2 V voltage stimulation mainly enhanced salt-in strategy of halotolerant microorganisms, and the intracellular Na⁺ and K⁺ concentration ratio of EMR to MR reached maximum and minimum values of 0.65 and 1.92, respectively. Furthermore, the results of microbial metagenomic and metatranscriptomic analysis showed the halotolerant microorganisms Pseudomonas_A and Nitratireductor with p-CNB removal ability were enriched significantly under 1.2 V voltage stimulation. And the gene expression of p-CNB removal, salt-in strategy and betaine transporter were enhanced under voltage stimulation at varying salinities. Our investigation provided a new solution which combined with 1.2 V voltage stimulation and halotolerant microorganisms for the treatment of high-salinity wastewater.

Keywords: Halotolerant microorganism; High-salinity wastewater; Low-voltage stimulation.

MeSH terms

Bioreactors
Salinity*
Salt Tolerance
Sewage / chemistry
Sodium Chloride
Wastewater*

Substances

Wastewater
4-chloronitrobenzene
Sodium Chloride
2-chloronitrobenzene
Sewage