| Title | Bioelectrochemical approach for reductive and oxidative dechlorination of chlorinated aliphatic hydrocarbons (CAHs) |
| Abstract | A sequential reductive-oxidative treatment was developed in this study in a continuous-flow bioelectrochemical reactor to address bioremediation of groundwater contaminated by trichloroethene (TCE) and less-chlorinated but still harmful intermediates, such as vinyl chloride. In order to optimize the anodic compartment, whereby the oxygen-driven microbial oxidation of TCE-daughter products occurs, abiotic batch experiments were performed with various anode materials poised at +1.20 V vs. SHE (i.e., graphite rods and titanium mesh anode coated with mixed metal oxides (MMO)) and setups (i.e., electrodes embedded within a bed of silica beads or graphite granule). The MMO anode displayed higher efficiency (>90%) for oxygen generation compared to the graphite electrodes. Additionally, the graphite bed presence adversely affects oxygen generation, likely due to the oxygen scavenging. This effect was completely eliminated by replacing the graphite granules with silica beads. The anodic setups were thereafter verified in a mentioned reactor at an applied TCE loading rate of approximately 20 ?M d-1 and a hydraulic retention time of 1.4 d in each compartment. The cathode consisted of a bed of graphite granules and was potentiostatically controlled at -0.65 V vs. SHE. The best reactor performance in terms of removal efficiency (i.e., >97%), removal rate (i.e., 121.8 ± 2.7 ?eq L-1 d-1), and the residual concentration (i.e., 5.03 ± 0.63 ?eq L-1) of chlorinated contaminants was achieved with the MMO anode placed in a silica bed. Ecotoxicity tests performed with algae confirmed these results by showing progressive toxicity reduction from inlet to cathodic and anodic effluent using this reactor configuration. |
| Source | Chemosphere 169, pp. 351–360 |
| Keywords | BioremediationChlorinated solventsMMO anodesOxidative dechlorination |
| Journal | Chemosphere |
| Editor | Elsevier, Oxford, Regno Unito |
| Year | 2017 |
| Type | Articolo in rivista |
| DOI | 10.1016/j.chemosphere.2016.11.072 |
| Authors | Lai, Agnese; Aulenta, Federico; Mingazzini, Marina; Palumbo, Maria Teresa; Papini, Marco Petrangeli; Verdini, Roberta; Majone, Mauro |
| Text | 372306 2017 10.1016/j.chemosphere.2016.11.072 Scopus 2 s2.0 84997194261 Bioremediation Chlorinated solvents MMO anodes Oxidative dechlorination Bioelectrochemical approach for reductive and oxidative dechlorination of chlorinated aliphatic hydrocarbons CAHs Lai, Agnese; Aulenta, Federico; Mingazzini, Marina; Palumbo, Maria Teresa; Papini, Marco Petrangeli; Verdini, Roberta; Majone, Mauro Universita degli Studi di Roma La Sapienza; Consiglio Nazionale delle Ricerche; Istituto di Ricerca sulle Acque, Italy A sequential reductive oxidative treatment was developed in this study in a continuous flow bioelectrochemical reactor to address bioremediation of groundwater contaminated by trichloroethene TCE and less chlorinated but still harmful intermediates, such as vinyl chloride. In order to optimize the anodic compartment, whereby the oxygen driven microbial oxidation of TCE daughter products occurs, abiotic batch experiments were performed with various anode materials poised at 1.20 V vs. SHE i.e., graphite rods and titanium mesh anode coated with mixed metal oxides MMO and setups i.e., electrodes embedded within a bed of silica beads or graphite granule . The MMO anode displayed higher efficiency >90% for oxygen generation compared to the graphite electrodes. Additionally, the graphite bed presence adversely affects oxygen generation, likely due to the oxygen scavenging. This effect was completely eliminated by replacing the graphite granules with silica beads. The anodic setups were thereafter verified in a mentioned reactor at an applied TCE loading rate of approximately 20 M d 1 and a hydraulic retention time of 1.4 d in each compartment. The cathode consisted of a bed of graphite granules and was potentiostatically controlled at 0.65 V vs. SHE. The best reactor performance in terms of removal efficiency i.e., >97% , removal rate i.e., 121.8 ± 2.7 eq L 1 d 1 , and the residual concentration i.e., 5.03 ± 0.63 eq L 1 of chlorinated contaminants was achieved with the MMO anode placed in a silica bed. Ecotoxicity tests performed with algae confirmed these results by showing progressive toxicity reduction from inlet to cathodic and anodic effluent using this reactor configuration. 169 Published version http //www.scopus.com/record/display.url eid=2 s2.0 84997194261 origin=inward Articolo in rivista Elsevier 0045 6535 Chemosphere Chemosphere Chemosphere Chemosphere. Chemosphere. Environmental chemistry, Chemosphere. Persistent organic pollutants and dioxins, Chemosphere. Environmental toxicology and risk assessment, Chemosphere. Science for Environmental toxicology, mariateresa.palumbo PALUMBO MARIA TERESA marina.mingazzini MINGAZZINI MARINA federico.aulenta AULENTA FEDERICO |
