New design of an electrocoagulation reactor to remove pollutants from groundwater: Analysis and optimization using response surface methodology

Abstract

Batch electrocoagulation experiments were done using a new design of monopolar-parallel electrodes. The process was conducted to make groundwater suitable for municipal use by removing TDS, TSS, Ca+2, Mg+2, SO4–2, and NO3–1 ions. These electrodes were ‎designed as a finned anode made of aluminum and placed concentrically through in ‎a ‎tubular cathode. The new design of the anode has provided a significantly higher ‎active area compared to its wet volume. Response surface methodology (RSM) type central composite design (CCD) was used for design experiments, analysis, and optimization. The treatment process was studied at room temperature by examining reaction time (4–30 min), applied current (0.2–2.4 Amp.), and mixing speed (50–250 rpm). As observed, all pollutants' removal was directly proportional to the operating parameters attaining considerable eliminating efficacious for initial concentrations of TDS, TSS, Ca+2, Mg+2, SO4–2, and NO3–1 ions of 1514, 57.73, 1744.44, 1308, 180, and 32.6 mg/l, respectively. The optimal values of reaction time of 13 min, 2.3 Amp of applied current, and 50 rpm of mixing speed provided 81.16% of TDS removal and 85.26% of TSS removal with low consumption of electrical energy and electrodes (2.4 kWh/m3 and 0.25 g). Moreover, the parameter of the ohmic potential drop (OPD) was investigated. The obtained results revealed that the present design was less affected by this essential parameter. As well, the behavior of solution temperature throughout the EC reactor was studied. The thermodynamic study proves that the present electrocoagulation process was endothermic, spontaneous in nature, and randomness of the solution interface. In summary, the core results proved that the new configuration of electrodes employed in the electrocoagulation reactor was cost-effective, reliable and environmentally applicable for the treatment of real groundwater compared to the conventional design of EC electrodes.