哈尔滨工业大学工程硕士学位论文

BOD5, SS, TP, NH4+-N and TN of the wastewater treatment plant were 184, 53, 57,

2.65, 20.6 and 27.4 mg/L. The pretreatment unit exhibited fairly low efficiencies for the COD, BOD5 and NH4+-N, which were mainly eliminated in the pre-denitrification biological aerated filter. The pre-denitrification biological aerated filter achieved removal efficiencies of 63%, 69.4% and 57.6% for COD, BOD5 and NH4+-N, respectively. The average removal efficiencies for SS and TP also reached to 60% and 56.9%. And 45% removal of TN on average was achieved by the whole process chain. The effluent qualities could meet the maximum allowable discharging concentration as desired. In addition, the influent and effluent water qualities of the wastewater treatment plant were shown to be fairly stable; the pH of the final effluent fluctuated in the small range of 7.4 to 7.7. To a large extent, biological water purification function was influenced by the water temperature. Well at low temperature, the biological activity of microorganisms will be lowered correspondingly, and the major functional microbial community may even be changed. In Daqing, there are usually 3~5 months in a year when the water temperature of raw wastewater is as low as about 10 ℃. During January, the average influent COD, BOD5, SS, TP, NH4+-N and TN concentrations of the wastewater treatment plant were 254.6, 106.7, 65.1, 3.4, 27.4 and 32.1mg/L, respectively. Pre-denitrification biological aerated filter achieved average COD removal efficiency of 63%, average BOD5 removal efficiency of 77.4%, average SS removal efficiency of 65%, average NH4+-N removal efficiency of 52%, and average TP removal efficiency of 82.7%. The average TN removal rate by the whole process reached to 60.2%. Effluent pH fluctuated in the range of 7.2 to 7.5.

After the implementation of the project, the qualities of urban wastewater with treatment met the first level B standard of GB18918-2002. The water environment quality of the receiving water has been improved significantly.

Keywords: wastewater treatment plant, biological aerated filter, pre-denitrification