Electrocoagulation treatment of peat bog drainage water containing humic substances

• Electrocoagulation (EC) of a synthetic humic acid solution was optimized.
• Large-scale EC treatment of real peat bog drainage water (PBDW) was successful.
• Evaluation of the economic values of the EC process was performed.
• EC is a feasible treatment method for PBDW containing humic substances.
• A novel application (PBDW treatment) for EC is discussed.

Electrocoagulation (EC) treatment of 100 mg/L synthetic wastewater (SWW) containing humic acids was optimized (achieving 90% CODMn and 80% DOC removal efficiencies), after which real peat bog drainage waters (PBDWs) from three northern Finnish peat bogs were also treated. High pollutant removal efficiencies were achieved: Ptot, TS, and color could be removed completely, while Ntot, CODMn, and DOC/TOC removal efficiencies were in the range of 33–41%, 75–90%, and 62–75%, respectively. Al and Fe performed similarly as the anode material.Large scale experiments (1 m3) using cold (T = 10–11 °C) PBDWs were also conducted successfully, with optimal treatment times of 60–120 min (applying current densities of 60–75 A/m2). Residual values of Al and Fe (complete removal) were lower than their initial values in the EC-treated PBDWs.Electricity consumption and operational costs in optimum conditions were found to be low and similar for all the waters studied: 0.94 kWh/m3 and 0.15 €/m3 for SWW and 0.35–0.70 kWh/m3 and 0.06–0.12 €/m3 for the PBDWs (large-scale). Thus, e.g. solar cells could be considered as a power source for this EC application. In conclusion, EC treatment of PBDW containing humic substances was shown to be feasible.

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