Journal of Environmental Biology

Cometabolic biodegradation of chlorinated ethenes with methanotrophs in anaerobic/aerobic simulated aquifer

S.K. Chen¹, Y.L. Chin¹, H.Y. Yang¹, C.J. Lu¹ and M.H. Liu²* 

¹Department of Environmental Engineering, National Chung Hsing University, 145 Xingda Rd., Taichung-402204, Taiwan

²Department of Environmental Engineering and Management, Chaoyang University of Technology, 168, Jifeng E. Rd., Taichung-413310, Taiwan

*Corresponding Author Email : jliu@cyut.edu.tw

Received: 09.01.2021                                                               Revised: 06.04.2021                                                   Accepted: 03.05.2021

Abstract

Aim: This study explores anaerobic/aerobic biodegradation efficiencies of aerobic cometabolism with methanotrophs when contaminants trichloroethylene (TCE) and cis-1,2-dichloroethylene (cDCE) are present individually or in tandem.

Methodology: Batch tests and an anaerobic/aerobic column system were used to simulate saturated, contaminated aquifers. A brown glass bottle with an effective volume of 44 m l^-1 was prepared for the batch test. An integrated one-dimensional sequential anaerobic/aerobic column system was used to simulate the accumulative intermediates such as TCE, cDCE and VC caused by incomplete degradation of PCE during the upgradient anaerobic stage in the saturated aquifer. In the downgradient aquifer, aerobic cometabolism was employed to degrade the intermediates. Methanotrophs in the aerobic aquifer were inoculated to degrade the by-products of incomplete degradation of PCE by aerobic cometabolism.

Results: In the batch test, biodegradation of TCE was significantly inhibited by cDCE. However, biodegradation of cDCE was not significantly inhibited by TCE. In the simulated aquifer test, aerobic cometabolism completely degraded intermediates (TCE, cDCE, and VC) produced by incomplete anaerobic degradation of tetrachloroethylene (PCE). The results showed that methane, a by-product of anaerobic reductive dechorination of PCE, was used as a primary substrate for aerobic degradation, at a utilization rate of almost 100%.      

Interpretation: Biodegradation of TCE was significantly inhibited by cDCE. Bioremediation should have sufficient oxygen and methane at aerobic stage to ensure that chlorinated ethenes fully mineralize.

Key words: Aerobic cometabolism, Anaerobic/aerobic biodegradation, cis-1,2-dichloroethylene, Methanotrophs,Trichloroethylene

Copyright © 2021 Triveni Enterprises. All rights reserved. No part of the Journal can be reproduced in any form without prior permission. Responsibility regarding the authenticity of the data, and the acceptability of the conclusions enforced or derived, rest completely with the author(s).