| Summary: | 碩士 === 國立中興大學 === 環境工程學系所 === 105 === In consideration of more and more strict requirements of environmental laws and regulations, improving ammonia nitrogen removal rate is one key point for the current water pollution prevention. Moreover, ammonia nitrogen also causes critical damage to aquatic living beings and it is the main pollutant that leads to eutrophication of water body. Given that the environmental awareness of the populace is increasing, environmental issues attracts the attention of the public, and the impact of global climate change, the recycling and reuse of the water is highly valued under the status of water resources supply and instability.
Therefore, the study collected and analyzed data from a sewage treatment plant of oxidation ditch in central area, and observed and adjusted the operational status at site, and then explored the effectiveness of oxidation ditch on ammonia nitrogen removal through various water quality testing. The oxidation ditch was failed to be effectively adjusted to the ideal operational status due to the issue of high grease and bubbles on the inflow wastewater during the research process; especially the critical factor, dissolved oxygen (DO), it was not improved even after adding a lot of aeration. We encountered heavy rain when finally achieved the stable and effective status and lost part of activated sludge so that the study outcomes were not ideal with 4.43 mg/L ammonia nitrogen removal of oxidation ditch, ammonia nitrogen removal rate of 17.53%, and 7mg/L alkalinity reduction as CaCO3. Furthermore, the relevant information summarized from the same sewage treatment plant in 2015 found the ammonia nitrogen removal rate could achieve up to 79.63% and it proves oxidation ditch is actually with great effectiveness of ammonia nitrogen removal.
Putting all the information collected and tested in the study together, we find the operational conditions that should be controlled in terms of oxidation ditch are the C/N ratio of inflow wastewater, the dissolved oxygen in the oxidation ditch, the detention time of activated sludge, the emission of hazardous substance, and the adjustment and control of aeration methods. With the good adjustment and control of the above factors, the effectiveness of ammonia nitrogen removal in oxidation ditch should be able to achieve the best status.
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