Evaluation of the Bioelectrochemical Approach and Different Electron Donors for Biological Trichloroethylene Reductive Dechlorination

Abstract

Trichloroethylene (TCE) and more in general chlorinated aliphatic hydrocarbons (CAHs) can be removed from a contaminated matrix thanks to microorganisms able to perform the reductive dechlorination reaction (RD). Due to the lack of electron donors in the contaminated matrix, CAHs’ reductive dechlorination can be stimulated by fermentable organic substrates, which slowly release molecular hydrogen through their fermentation. In this paper, three different electron donors constituted by lactate, hydrogen, and a biocathode of a bioelectrochemical cell have been studied in TCE dechlorination batch experiments. The batch reactors evaluated in terms of reductive dechlorination rate and utilization efficiency of the electron donor reported that the bio-electrochemical system (BES) showed a lower RD rate with respect of lactate reactor (51 ± 9 µeq/d compared to 98 ± 4 µeq/d), while the direct utilization of molecular hydrogen gave a significantly lower RD rate (19 ± 8 µeq/d), due to hydrogen low solubility in liquid media. The study also gives a comparative evaluation of the different electron donors showing the capability of the bioelectrochemical system to reach comparable efficiencies with a fermentable substrate without the use of other chemicals, 10.7 ± 3.3% for BES with respect of 3.5 ± 0.2% for the lactate-fed batch reactor. This study shows the BES capability of being an alternative at classic remediation approaches.

Sequential Anaerobic/Aerobic Microbial Transformation of Chlorinated Ethenes: Use of Sustainable Approaches for Aquifer Decontamination

“…According to Dell'Armi and colleagues [138], the dechlorination efficiency reached by BES and by the addition of fermentable substrates such as lactate was comparable.…”

A Polyhydroxybutyrate (PHB)-Biochar Reactor for the Adsorption and Biodegradation of Trichloroethylene: Design and Startup Phase

“…Environmental issues associated with chlorinated aliphatic hydrocarbons (CAHs), e.g., chlorinated solvents, contamination can be attributed to the high frequency of detection of these compounds in groundwater and their high persistence and toxicity [1]. The remediation of groundwater contaminated by chlorinated solvents, harmful compounds classified as carcinogenic by the Italian legislature [2], has been usually carried out using energy-intensive technologies (e.g., pump-and-treat or chemical treatment) [3]. "In-Situ" biological technologies have been introduced in recent years as an alternative to traditional methods [4][5][6].…”

“…"In-Situ" biological technologies have been introduced in recent years as an alternative to traditional methods [4][5][6]. Particularly, highly chlorinated compounds can be used as electron acceptors; thus, reduced in anaerobic conditions and contemporarily, an organic substrate is oxidized (e.g., lactate, butyrate, or other fermentable substrates), providing the real electron donor (H 2 ) [2]. Indeed, the metabolism of specific microorganisms (e.g., Dehalococcoides mccartyi (Dhc)) converts the parental compounds to more acceptable molecules, i.e., ethylene, through the biological reductive dechlorination (RD) reaction.…”

Advanced Nano-biotechnology for Chlorinated Volatile Compound Pollutants Control

“…1 dechlorination by the use of innovative technologies. Next, four recent approaches to greener and more sustainable technologies are proposed(Dell'Armi et al, 2022).…”