Читать книгу Sustainable Solutions for Environmental Pollution, Volume 2 - Группа авторов - Страница 43

Pollutant bench tests, often referred as microcosm studies, focus on the optimization of operational electrochemical parameters. Bench tests reach high removal for contaminants such as: nitrogen salts by cathode ammonification and anode denitrification processes (Zhang et al., 2020b); crude oil and PAH contaminations (Mohan and Chandrasekhar, 2011; Morris and Jin, 2012; Li et al., 2014; Lu et al., 2014a; Viggi et al., 2015; Venkidusamy et al., 2016; Daghio et al., 2017; Kronenberg et al., 2017; Li et al., 2017b; Yan et al., 2017; Yu et al., 2017; Palma et al., 2018; Li et al., 2020; Zhang et al., 2020b); solvents (Strycharz et al., 2008; Zhang et al., 2010; Daghio et al., 2016); OM (Morris and Jin, 2012; Venkidusamy et al., 2016; Gonzalez-Gamboa et al., 2017; Zhao et al., 2017), or pesticides (Rodrigo et al., 2014; Cao et al., 2015; Domínguez-Garay et al., 2018; Quejigo et al., 2018). Electro-bacteria can promote reductive remediation of organochlorine compounds (Aulenta et al., 2011; Yu et al., 2016). On its side, cathode electrode can remove heavy metal ions by metal reducing and depositing such as for Cu²⁺, Ag²⁺, and Hg²⁺. But, for metal ions with negative reduction potential, such as Pb²⁺, Cd²⁺, Zn²⁺, and Ni²⁺, energy input is required for reduction. However, this technique currently works only at bench scale and on synthetic solutions, thus avoiding the problem of metals bound to OM. Only an application on actual wastewater will be able to prove the relevance of electro-bioremediation in treatment of heavy metal pollutions (Bagchi and Behera, 2020).

Since electro-bioremediation involves a microbial consortium, it takes time to become operational: prior enrichment of the electrodes (bio-augmentation) accelerates the biodegradation capacities (Venkidusamy et al., 2016). The potential difference measurement between the anode and the cathode provides a way to monitor the set up progress of the microbial consortium, and its stabilization time varies with the device size. In bench tests it stabilizes after about 10 days: it takes 2 to 3 days in marine sediment (Najafgholi and Rahimnejad, 2016); 10 days in swamp sediment (Gonzalez-Gamboa et al., 2017) and Diesel-fed sludge (Venkidusamy et al., 2016); 13 days in tidal mud (An et al., 2010); and around 20 days in waterlogged soil (Yu et al., 2017; Zhang et al., 2020b). In pilot tests, it stabilizes about some tens of days: 35 days in TF-CWs (Arends et al., 2014; Schievano et al., 2017) crude oil contaminated marine sediment (Hamdan and Salam, 2020), and waste-contaminated river sediment (Yang et al., 2015); over 40 days in FSF-CWs (Oon et al., 2016). In field-experiments, because of the size, the voltage stabilization time is supposed to be longer.