Anaerobic digestion of organic wastewater from chemical fiber manufacturing plant: Lab and pilot-scale experiments

Chemical fiber manufacturing wastewater (CFMW) usually contains high levels of organic materials. Anaerobic digestion of CFMW was evaluated by the lab and pilot scale experiments in the study. The CFMW used in the experiment characterized an inappropriate C/N ratio and acid pH for anaerobic digestion. The COD removal efficiency, pH and the methane yield were significantly decreased with 5.00 g COD/L day of OLR in the lab scale experiment. These results were thought to be due to the inappropriate C/N ratio and acid pH of CFMW. Thus, the addition of nutrients and neutralization for CFMW were conducted in the pilot scale experiment. Accordingly, the significant decreases in COD removal efficiency and pH were not observed although the OLR increased to 5.00 g COD/L day. The methane yield also increased above 25% compared to that of the lab scale experiment. In the case of 1,4-dioxane, the removal efficiency was not improved significantly at the higher HRT. It was considered that constant proportion of acetic acid was used in the degradation of 1,4-dioxane as a cosubstrate regardless of HRT.