Comparison of electrocoagulation and chemical coagulation processes in the treatment of an effluent of a textile factory

In this work, electrocoagulation and chemical coagulation were applied to the exit effluent of a textile factory located at Douala (Cameroon).The investigations were focused on the operational (pH, conductivity) and pollution parameters (COD, total phosphorus, turbidity). The electrolytic treatment was carried out with 0.4 A current intensity, and chemical coagulation was conducted in adding initially to the effluent the same quantities of aluminium than that electrogenerated.the elimination of pollution contents depended on the quantity of Al3+ ions produced by the electrodissolution of the aluminium anode and that of the aluminium salt dissolved in solution. In fact, 58.86, 94.44 and 97.81% of COD, total phosphorous and turbidity were respectively removed by electrocoagulation, while hemical coagulation, the turbidity was also reduced roughly at the same level as by electrolytic treatment. Also, 56.08 and 63.64% COD and total phosphorus were respectively removed by chemical route. During electrocoagulation, highest removals were reached after 2.49x10-3mmol of aluminum was released in solution (after 30 minutes of treatment). Thus, the final pH obtained by this process was around 9 and the conductivity varying slightly, compared to the initial value. By contrast, chemical coagulation rendered the effluent more acidic and more conducting (γ> 4 mS.cm-1). Electrocoagulation is the best process, by the fact that the textile effluent treated by this technique can be re-used or rejected without risk in the environment. Chemical coagulation: indeed, the corrosive nature of effluent treated by this method and the significant content of the residual phosphorus can seriously inhibit the perspective of recycling.Keywords: Electrocoagulation, Chemical coagulation, Textile effluents, Removal efficienc

Investigation and optimization of a new electrocoagulation reactor with horizontal bipolar electrodes Effect of electrode structure on the reactor performances

International audienceThe performances of a new electrocoagulation reactor with bipolar horizontal iron electrodes were investigated. These electrodes were piled up in the reactor in order to maintain a low gap between them and to increase the electroflotation process. Electrodes were perforated to allow the passage of gas and effluents, and adjacent ones were separated by grids of polyamide or polytetrafluoroethylene. The performances of the reactor were investigated thanks to the weight lost of the electrodes. These performances increased with the number of holes in the electrodes, the current intensity, and the flow rate of the effluent, and mainly in the absence of a gap between the electrode edges and the walls of the reactor. More important, when the electrodes were not sealed with a system of tightness a decrease of the current efficiency was observed, leading to higher voltage and contributing to increase considerably the energy consumption. The use of eight-hole electrodes and a high flow rate reduced significantly the voltage and increased the current efficiency. Moreover in the absence of a gap between electrode edges and reactor walls, the current efficiency reached 100%; the voltage was stable and did not vary anymore and the energy consumption was minimized. The results showed that the sealing between electrode edges and the walls of the reactor was the most determinant factor in the optimization of the investigated reactor. © 2018 Elsevier Ltd. All rights reserved