Evaluation of the Effect of an Upflow Biofilter on the Enhancement of Influent Quality for a Water Treatment Plant

The hydraulic characteristics of Nakdong River, which is used as a source of drinking water, are similar to a series of lakes due to the construction of several weirs. This has resulted in the deterioration of the water quality of the river due to the inflow of various pollutants (e.g., organics, nitrogen, phosphorus, and nonbiodegradable matter). The objectives of this research were to evaluate the performance of an upflow biofilter (UBF) packed with zeocarbon in improving the river water quality. As the filtration velocity increased from 100 to 200m/d for the UBF bed, the removal efficiency decreased from 74.5±7.5 to 23.4±2.45% for the chemical oxygen demand, increased from 3.5±6.2 to 55.2±9.0% for suspended solids, increased from 64.8±1.8 to 89.9±1.7% for NH₄-N, and decreased from 91.2±2.9 to 60.0±10.2% for E.coli. The removal efficiencies thus decreased with a higher filtration velocity. Despite the fluctuation in the river water quality, a filtration velocity lower than 150 m/d led to a stable treatment performance and produced Grade I river water quality as a source of drinking water. Evaluating the biodegradation rate of the UBF bed using zeocarbon, the results show that the dissolved organic carbon was 0.198 gDOC/kgZCday. In particular, the biodegradation of the UBF after backwashing increased with a lower filtration velocity. These results indicate that the use of UBFs is effective for enhancing river water quality.