Dissolved oxygen control system for upgrading conventional activated sludge process for seafood industrial wastewater in Southern Thailand

The objective of this study is to upgrade the operation of conventional activated sludge treatment plants for the purpose of saving aeration energy and at the same time providing better utilization of existing plant capacity for nutrient removal without major investment. In this study, pilot-scale experiments of the single stage activated sludge process (ASP), as operated in existing ASP in southern Thailand by using wastewater from seafood industry, was conducted under conditions of simultaneous nitrification-denitrification. However, achieving these conditions required appropriate dissolved oxygen P. Chevakidagarn, A. P. Annachhatre, U. Puetpaiboon and T. Koottatep Asian J. Energy Environ., Vol 8, Issue 1 and 2, (2007), pp. 1-14 2 (DO) concentrations. An aeration control system is needed. This study investigated the possibility of using the oxidation-reduction potential (ORP) value as the parameter for controlling aeration in the simultaneous nitrification-denitrification system. The aeration control system was operated to control the ORP values varied between -300 to 100 mV. The results in this study indicated that the simultaneous nitrification-denitrification process might be suitable for improving nitrogen removal in the seafood industry. Total nitrogen removal could reach up to 82 percent at controlled ORP of 50 mV. Results also showed that the volume of air supplied per mg of TN removed per minute was least when ORP was controlled at 0 mV (0.1 mL of air supplied per mg of removed TN per minute). Less aeration energy consumption was not observed for a lower ORP setting. However, this result could not be definitely concluded for every type of wastewater.