| Summary: | 博士 === 逢甲大學 === 環境工程與科學學系 === 104 === Owing to the pattern of livestock farming in Taiwan is concentrate feeding. High amount of organic and nitrogen content are therefore concentrated in the discharge wastewater. After releasing, it will consume dissolved oxygen of the natural water and cause toxicity effect to the aquatic organisms directly. Eventually it will downgrade the environmental quality. Currently the traditional three-stage treatment process only transfer nitrogen pollutants into nitrite and nitrate, but can’t remove them completely from the livestock wastewater. Hence, the objective of this study is to enhance the treatment efficiency of nitrogen pollution by integrating nitrification and denitrification processes altogether. In our study, partial aeration process and an anaerobic soil adsorption system are applied to fulfill this purpose.
This study is divided into two phases. At the beginning domestic sewage was used to domesticate sludge. In the next phase, livestock wastewater of pig farm was used to validate the efficiency of the treatment system. Five sections, influent water storage tank, two aeration tanks, adjustment tank and a soil adsorption unit are arranged sequentially in this experiment. During the process, anaerobic digesta are aerated by air sparging from bottom of two consequential tanks. It creates a suitable condition to oxide ammonia nitrogen into nitrite and nitrate ultimately. At adjustment tank, dissolved oxygen is consumed continuously. A saturated soil adsorption column then provides an anaerobic environment to take place denitrification process.
Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD), and nitrogen contents, ammonia nitrogen, nitrite, nitrate, Total Kjeldahl Nitrogen (TKN) and total nitrogen (TN), are measured and calculated to evaluate the efficiency of treatment. According to the experimental design, effluent samples from each section are taken in every seven days.
As a result both the organic contents and nitrogen contents are decreased. The concentration of BOD and COD is decreasing from 132 to 54 mg/L and 270 to 150 mg/L, respectively. The concentration of ammonia nitrogen, TKN and TN is decreasing from 553 to 140 mg/L, 639 to 156 mg/L and 640 to 179 mg/L, respectively. The removing efficiency of ammonia nitrogen, TKN and TN are 75%, 76% and 72%, respectively. Compare to the results of traditional three-stage treatment, the removal efficiency of nitrogen contents is 1.64 times greater in this study.
Furthermore, the effluent of this treatment system is fulfilled the criteria of regulatory effluent standards. The nitrification-denitrification systems in this study not only reduce the environmental loading of swine manure wastewater discharge but also provide an alternative for water resource reusing.
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