Optimization of guava juice wastewater electrochemical treatment

Wastewater from guava juice production was treated by two electrochemical processes: Electroflotation (EF) and Electrocoagulation (EC). Using Box-Behnken experimental design, these processes were optimized in order to find the values of treatment time, initial pH and current density that lead to the maximum chemical oxygen demand (COD) removal efficiencies. Aluminum electrodes were used in EC treatment and an iron cathode and a ruthenium dioxide / titanium dioxide anode were applied in EF treatment. EC treatment resulted in maximum COD removal of 60%, when treating the wastewater for 40 minutes, with initial pH 4.5 and current density of 35 A/m2. On the other hand, EF only removed 25% of the wastewater COD (treatment time 40 minutes, initial pH 7.0 and current density 45 A/m2). Aluminum sulfate addition improved the wastewater conductivity, lowering electricity consumption rates. Moreover, the treatment combining EF and this chemical coagulant lead to better results than the ones found when using EF alone.