Operating parameter Training RMSE Checking RMSE Electrolysis time ×Current density 9.43 10.43 Electrolysis time ×pH 9.53 9.26 Current density ×pH 5.04 5.47

Note: Input variable with the least training RMSE is the most relevance with respect to COD removal efficiency.

Table 4: Results from adaptive neuro-fuzzy inference system for selecting the combination of two operating parameter that mostly influences the COD removal efficiency.