TOC and COD removal from instant coffee and coffee products production wastewater by chemical coagulation assisted electrooxidation

This paper describes and discusses an investigation into the treatment performance of Boron-Doped Diamond (BDD), N coated Ti (N) and various Mixed Metal Oxide (MMO) anodes after pre-treatment chemical coagulation for total organic carbon (TOC) and chemical oxygen demand (COD) removal from instant coffee and coffee products production wastewater. Firstly, the performance of coagulants, AlCl3,Al-2(SO4)(3), FeCl3 and FeSO4 were investigated. Secondly, the treatment performance of BDD, N and various MMO anodes, the influence of the applied current density and the effect of flow rate for the best-performed electrode were investigated. Also, specific energy consumptions and anode performances were calculated and evaluated for electrooxidation process. At the pre-treatment, among the four coagulants, AlCl3 showed the best performance removing 29% TOC and COD 55%. At the electrooxidation process, BDD electrode achieved the best performance. At the end of the 6 h run period, BDD electrode achieved 95% TOC and 97% COD removal. On the other hand, N and MMO electrodes just removed 13-22% TOC and 25-50% COD respectively. In this study, the BDD electrode performed much better than N and MMO electrodes.