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

Abstract

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.