Degradation of N-methylpyrrolidone in High Salinity Wastewater by a Halotolerant Microorganism

Liqun Wang,Ran Xia,Guorui Zhang,Jing Wang

doi:10.5296/jbls.v11i1.16310

Abstract

N-methylpyrrolidone (NMP), a nitrogen-containing heterocyclic compound, is widely used in lithium batteries and the refining of lubricants. However, it is also very harmful to human health and the environment. Although NMP is biodegradable, industrial high salinity wastewater can stop microorganisms from growing. To effectively degrade NMP in high salinity wastewater, a halotolerant strain CCZU-X was isolated from sea shrimps. The strain was identified as Staphylococcus lentus through morphology observation and 16S rDNA sequencing. The effects of processing conditions such as salt concentration, pH, and temperature on degradation of high salinity NMP-containing wastewater were investigated using single-factor experiments. Quantitative analysis of degradation efficiency of NMP was conducted by high-performance liquid chromatography. The optimal conditions for CCZU-X to degrade NMP in high salinity wastewater were determined to be at pH 7.0 and 35 °C, and the maximum salt tolerance was 25%. Under optimal conditions (pH 7.0, 35 °C, 1% salt, 2000 mg/L NMP), the NMP degradation efficiency of CCZU-X reached 93%. This strain can effectively degrade NMP in high salinity NMP-containing wastewater, thus can be potentially used in industrial applications.

Highlights

N-methylpyrrolidone (NMP) is a colorless and transparent aprotic liquid with a slight ammonia odor
To effectively degrade NMP in high salinity wastewater, a halotolerant strain CCZU-X was isolated from sea shrimps
Quantitative analysis of degradation efficiency of NMP was conducted by high-performance liquid chromatography

Summary

Introduction

N-methylpyrrolidone (NMP) is a colorless and transparent aprotic liquid with a slight ammonia odor. The Globally Harmonized Classification and Labeling System of Chemicals issued by the United Nations lists the acute toxicity of NMPs as Category 4(Fine & Mullin, 2017). Akesson’s research showed that NMP is very stable not degradable by chemical methods(Akesson & Paulsson, 1997), but according to Casi, it is prone to biodegradation under aerobic conditions(Shu et al, 2014). Biodegradation methods can be really effective at degrading NMP in wastewater. Existing NMP wastewater treatment often use physical and chemical methods(Loh et al, 2018). These methods are complicated and costly, and requires a series of specific equipment(Chen & Xu, 2010). Little research covered NMP treatment in high salinity wastewater. Test were done in high salinity wastewater to simulate the conditions in practical applications

Main Equipments

Screening of the Halotolerant Strain

Determination of Salt Tolerance of the Strain

Effect of Initial NMP Concentration on the Growth of the Strain

Degradation Characteristics of the Strain

Results

Discussion