| dc.description.abstract | With the rapid development of residential, industrial, and agricultural sectors, a considerable amount of nitrogen pollution is being released into receiving water bodies, causing eutrophication of freshwater ecosystems and posing a serious threat to aquatic organisms as well as human health and safety. Furthermore, domestic regulations regarding the water quality requirements for discharged water have become stricter. Therefore, it is vital to investigate the treatment processes and performance of wastewater treatment plants to meet the discharge standards set by regulations.
The purpose of this research is to investigate the performance of the Oxic-Anoxic-Oxic (OAO) biological nitrogen removal process with a pilot plant at Taoyuan North District Water Resource Center. The designed flow rate of the pilot plant is 3-4 CMD. The study investigates the OAO process′s pollution removal efficiency and proposes suitable operation parameter ranges. It also looks into the utilization characteristics of sludge surface-adsorbed organic matter.
Under a hydraulic retention time (HRT) of 10-12 hours, the removal rates of COD, BOD, ammonia nitrogen, and total nitrogen are all above 80%, 90%, 90%, and 60% respectively, meeting the discharge criteria. However, the results of various HRTs indicate that a minimum HRT of 6 hours of the first oxic tank should be designed to ensure sufficient reaction time for nitrification. The distribution of oxic:anoxic:oxic tanks at a ratio of 5:4:1 demonstrates better and more stable nitrogen removal capability, providing sufficient volume for the anoxic tank to enhance the tolerance of residual dissolved oxygen, thereby effectively improving denitrification capacity. Based on the research results, it is recommended to adjust the design parameters as follows: HRT of 10-16 hours, F/M value of 0.05-0.15 kg BOD/kg MLSS∙d, and an aerobic sludge retention time (ASRT) of 15-30 days, as design guidelines.
The adsorption test results reveal that after the consumption of organic matter in the system, activated sludge can hydrolyze the adsorbed organic matter on its surface to obtain energy and support microbial growth. Furthermore, comparing the specific denitrification nitrate removal (SDNR) value to the system-based denitrification rate derived from mass balance, it is evident that hydrolysis of SBCOD(slowly biodegradeble COD) enables the post-denitrification configuration to possess a denitrification potential similar to the pre-denitrification configuration. This indicates the viability of using adsorbed SBCOD and organic matter storaged in activated sludge cells as carbon sources for denitrification in the OAO process.
In this study, good pollutant removal rates were obtained under various F/M conditions, making it difficult to determine the effect of F/M on the OAO process. However, the adsorption test indicates that higher F/M values result in higher utilization efficiency of organic matter in hydrolysis process. As a result, future research should conduct to investige the effect of F/M on the efficiency of the OAO process. | en_US |