| Summary: | 碩士 === 國立高雄第一科技大學 === 環境與安全衛生工程研究所 === 103 === In some industrial wastewater, there were high concentrations of ammonia and COD, and contained some biodegradable persistent substance such as phenolic, CN- and SCN-, PAHs. In the wastewater treatment plants, usually, the high concentration wastewater was mixed with low concentration wastewater, such as sewage, to reduce the concentration of toxic or biodegradable persistent substance. After dilution, it could be treated by activated sludge process and was useful for COD removal. Unfortunately, it still could not remove the ammonia from wastewater.
In general, the biological denitrification/nitrification process was used to remove ammonia from wastewater, but the HRT of this process was 5 – 7 days and it means to need more land for wastewater treatment plant. It is very difficult for some industrial factors to get land. Therefore, it is necessary to develop the high efficiency of the biological denitrification/ nitrification process. In this study, a modified biological denitrification/ nitrification process was used to treatment coking wastewater and the HRT of this process could be shortened to 40 hrs. The objects of this study were the consideration of the startup strategy for the modified biological denitrification/ nitrification process and the efficiency of this process for coking wastewater treatment.
The modified biological denitrification / nitrification process was consisted of 4 units, denitrification unit COD removal unit, nitrification unit and MBR unit. To compare the startup strategy, two similar processes were operated in the same time. The startup strategy of A process was the startup of the nitrification unit in low COD concentration at first. After the conversion rate of the nitrification unit was higher than 50%, the denitrification unit would be started at the second step. On the other hand, the startup strategy of B process was the startup of the nitrification unit and the denitrification unit at the same time with the addition of nitrate sodium in wastewater.
The results show that the ammonia conversion rate and COD removal rate could achieve above 50% and 85% in these two processes around one week, respectively, but the NOx- removal rate could not achieve above 50% until 4 weeks.
In comparison of the startup strategy of A and B process, the ammonia conversion rate and COD removal rate could be increased in B process, stably. The problem in the A process was how to removal COD in the first step in the real industrial factor. Therefore, the startup strategy of B process was more useful than A process.
The results of the batch experiments show that the denitrification bacteria could decompose SCN- and phenolics in low concentration, but the bacteria would be inhibited in high concentration.
In summary, the modified biological denitrification / nitrification process could be used for coking wastewater treatment and COD concentration and ammonia concentration were below than 115 mg/L and 12 mg N/L in treated water with 40 hrs, respectively.
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