Application of Taguchi Experimental Design Method for Optimization the COD Removal Process in Upflow Anaerobic Filter

In this study, two stages of upflow anaerobic filters (UAF) were used to investigate their performance based on the chemical oxygen demand (COD) removal from the rural domestic wastewater. Several factors were considered during the design and operation of an anaerobic process for successful treatment of the wastewater. Furthermore, Taguchi method was applied to investigate and evaluate the effect of selected factors on the performance efficiency of the UAF reactor. The experimental factors were optimized by L9 (34) orthogonal array design, which includes four factors with three levels using statistical analysis. The four factors involve the water acidity (pH), temperature (T), hydraulic retention time (HRT) and organic loading rate (OLR). The results revealed that all factors had a significant influence on the COD removal efficiency. The results demonstrated that the optimum conditions for achieving maximum COD removal efficiency were: initial pH of 7, temperature of 25°C, HRT of 1.5 day and OLR of 0.166 Kg. COD/m3.day. Moreover, the results showed that the HRT had highest percentage contribution in the COD removal process with 39.92%, followed by temperature of 33.78%, OLR of 13.75% and the pH of 9.18%. Confirmatory experiments conducted at the optimized conditions and compared with the predicted result show a good agreement.