Estimating seasonal and diurnal variations in influent wastewater characteristics for optimization of activated sludge system in a northern community

Abstract

Influent characterization experiments were carried out at the wastewater treatment facility in Fairbanks, Alaska. These experiments were carried out to trace the diurnal and seasonal variations in the influent flow and organic loading rates. A considerable difference in the wastewater flow and organic loading rates was -seen on a seasonal as well as a diurnal basis. The project hypothesized that better understanding of broad influent diurnal and seasonal variations in a wastewater-treatment facility can help optimize control strategies. Based on the observed variations, oxygen production and supply was analyzed as an avenue for optimization in the high purity oxygen activated system. The results indicate that up to 35% excess oxygen was being supplied on the sampling days despite the current control strategy. This excess maybe eliminated by including an upstream measurement device in the treatment scheme to enhance control over the process. Respirometry may improve the plant's ability to make suitable predictions for the oxygen requirements. Benefits of respirometry were discussed and several site-specific recommendations were rnade for the application of respirometric techniques at the Fairbanks wastewater treatment facility.