# Metal Recovery from Wastes: A Review of Recent Advances in the Use of Bioelectrochemical Systems
## 2 Bioelectrochemical Systems for Metal Recovery
\begin{table}
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**Objective** & **Reactor Setup** & **Operational Conditions** & **Milestones** & **Ref.** \\ \hline  & System: Dual-chamber MRC & Anolyte: Phosphate buffer + glucose & -Ag: 100\% recovery (7 h) & \\ Silver recovery from & Anode: Carbon felt (5 \(\times\) 5 cm) & Catholyte: Synthetic extract solution & -Cu: 60\% recovery (7 h) & [75] \\ photovoltaic panels & Cathode: Graphite paper (3 \(\times\) 3 cm) & (AgNO\({}_{3}\), CuCl\({}_{3}\), AlCl\({}_{3}\)) & -Al: 15\% recovery (7 h) & \\  & Membrane: Nafion\({}^{\circ}\) 115 & Rest: 100 \(\Omega\)/Temperature: 30 \({}^{\circ}\)C & -Maximum Ag removal: 99.8\% at & \\ \hline  & System: Dual-chamber H-type MRC & Anolyte: Synthetic wastewater & 100 mg/L Ag & \\ Investigating the effect of Ag & Anode: Carbon cloth (25 cm\({}^{2}\)) & (acetate 1 g/L, trace elements, neutral & -Ag recovery: 75\% in 2 h at & \\ concentrations on current & Cathode: Carbon cloth (55 cm\({}^{2}\)) with Pt & pH) & -Ag recovery: 75\% in 6 h at 50 mg/L & [76] \\ production and recovery & Membrane: Cation exchange membrane & Catholyte: Ag solution (6-95 mg/L) & -Batch operation up to 8 h & \\  & (Nafion\({}^{\circ}\) 117) & Temperature: 25 \({}^{\circ}\)C & investigated for varying Ag & \\  & & & & concentrations \\ \hline Feasibility of MRC technology & System: Dual-chamber MRC & Anolyte: Synthetic wastewater with & -Ag recovery: 93\% with NaClO\({}_{4}\) as & \\ for silver recovery from & Anode: Graphite paper (2.5 \(\times\) 3.8 cm) & 50 mg/L Ag & the supporting electrolyte & \\ synthetic PV hydrometallurgical & Cathode: Plain graphite paper & Catholyte: Phosphate buffer (pH\({}^{\circ}\)7, & -100\% Ag recovery at pH 2.00 in 3 h & \\ wastewater & Membrane: Proton exchange membrane & 0.16 g/L KCl) & -All & -All \\  & (Nafion\({}^{\circ}\) 117, 3.77 cm\({}^{2}\)) & Rest: 100 \(\Omega\)/Temperature: 32 \({}^{\circ}\)C & -Lower efficiency when KCl was & \\ \hline  & & Factors: cell concentration (OD 0.5 or & -Highest An removal (88.2\%)) & \\  & Serum bottle reactors (120 mL), 50 mL & 1), temperature (28 \({}^{\circ}\)C or 37 \({}^{\circ}\)C). & achieved with _S._enalysis_MR-1 at & \\  & solution, sealed with butyl rubber storage & anoxic/oxide, pH (1 or 5), Au\({}^{\circ}\) & 0.2 mM Au\({}^{\circ}\), pH 5, anoxic \\ Gold Recovery and & _Shownal anomalies across: MR-1 and Curylineus_ & concentration (0.2 mM or 2 mM), & conditions, and (electrogenerated) H\({}_{2}\) \\ Nanoparticle Synthesis in & _metallilatums CH34_ as bacterial strains & electron donor (electromechanical H\({}_{2}\) & as the electron donor. & \\ Microbial Systems Using & Electrochemical tests: Two-compartment BES & or lactate), bacterial species; batch & -Targeted An nanoparticle size & \\ Fractional Factorial Design & Electrodes: Carbon electrodes & incubation for 72 h. & (0.0 mm) obtained under optimal conditions & \\  & Electron donor: In situ hydrogen from & Electrochemical tests for H\({}_{2}\) & conditions & \\  & cathodic water reduction & generation: Carbon cathode poised at & -Significant role of pH and Au\({}^{3*}\) & \\  & & & -0.3 V vs. Ag/AgCl & concentration in removal efficiency \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._  
\begin{table}
\begin{tabular}{l l l l l} \hline
**Objective** & **Reactor Setup** & **Operational Conditions** & **Milestones** & **Ref. ** \\ \hline Alternative approach for Au & System: Dual-chamber MFC & \begin{tabular}{l} Analyte: Aqueous phase above \\ freshwater sediment \\ \end{tabular}  & \begin{tabular}{l} - In MES-mode (short-circulated), \\ \(>\)50\% Au recovered in 2 h, 100\% \\ recovered using microbial \\ electrochemical snorkel (MES) \\ \end{tabular}  & \begin{tabular}{l} [78] \\ \end{tabular}  \\  & \begin{tabular}{l} [8 cm\({}^{2}\)] \\ Membrane: Proton exchange (Nafion\({}^{\circ}\) 117) \\ \end{tabular}  & \begin{tabular}{l} [8 cm\({}^{2}\)] \\ Kernel 501 D \\ Temperature: 25 \({}^{\circ}\)C \\ \end{tabular}  & \begin{tabular}{l} [50] \\ \end{tabular}  \\ \hline Assessing _Castellanilla_ &