以改良式生物除臭系統處理硫化氫和氨氣廢氣之研究

Abstract

本論文根據不同污染源而設計三套除臭模式，因此分為三部份來詳加探討。第一部份：將養豬場廢水篩選到除臭效果佳之自營性硫氧化菌和自營性氨氧化菌以農產廢棄物製成之顆粒活性濾料 (GAM) 為擔體進行固定化。由於高濃度的氨氣和硫化氫會抑制自營性氨氧化菌代謝氨氣之能力，而氨氣之存在對自營性硫氧化菌代謝硫化氫之能力並無影響，故將濾料中微生物分別固定化於模場規模之串聯反應器中，前段充填自營性硫氧化菌，後段填充自營性氨氧化菌，以進行硫化氫和氨氣之去除實驗，探討去除特性、代謝產物、去除效率，並進行反應動力學之分析研究，且將此系統之排放濃度設定於「空氣污染防治法」所規定之周界環境標準以下，以滿足及應付趨嚴之空氣品質標準，符合空氣污染物排放標準。在硫化氫去除實驗方面，整個操作期長達210天，臨界負荷 (Critical loading) 為35 g-S/m3/h。當硫化氫進氣負荷達到52 g-S/m3/h時，去除能力將達到最大量(45 g-S/m3/h)。此外在無質傳影響及氧氣限制下利用Pseudo Michaelis-Menten動力式進行分析，活性濾料生物反應系統中代謝硫化氫之飽和常數 (ks) 為29 ppm，最大除硫效率 (Vm) 為1.5 (g-S/kg dry GAM/day)，整個210天操作期平均去除效率可以達98.7%以上，且停工效應(10天)對於除硫效率方面並無影響。本系統前半段之主要代謝物為硫元素，後半段主要代謝物為硫酸根和硫元素。在氨氣去除實驗方面，整個操作期長達210天，平均去除效率可達98.4%以上。長期去除中低濃度 (50 ppm) 之氨氣研究部分，去除效率皆能達100%去除效果。停工效應 (10天)方面，在復工兩天後，整個系統又恢復至原來的去除效率 (96%→100%)。本系統前半段主要代謝物為亞硝酸根和有機氮，後半段主要代謝物為亞硝酸根。 第二部分：將養豬場廢水篩選到除臭效果佳之異營性硫氧化菌和異營性氨氧化菌以農產廢棄物製成之顆粒活性濾料 (GAM) 為擔體進行固定化。由於高濃度的氨氣和硫化氫會抑制異營性硫氧化菌代謝硫化氫之能力，且高濃度的硫化氫會抑制異營性氨氧化菌代謝氨氣之能力，故將濾料中微生物分別固定化於模場規模之串聯反應器中，前段填充異營性氨氧化菌後段填充異營性硫氧化菌，以進行低濃度硫化氫/高濃度氨氣之去除實驗。在硫化氫去除實驗方面，整個操作期長達123天，濾床對於低濃度硫化氫 (30 ppm) 之去除效率方面皆可達100%之去除效果。停工效應 (10天)方面，對於整個系統在除硫效率方面並影響，除硫效率皆能達100%之去除效果。本系統前半段之主要代謝物為硫離子，後半段主要代謝物為硫元素和硫酸根。在氨氣去除實驗方面，整個操作期長達123天，臨界負荷(Critical loading) 為1.37 g-N/m3/h。當氨氣進氣負荷達到10.96 g-N/m3/h時，去除能力將達到最大量 (6.5 g-N/m3/h)，此為系統能承受的最大負荷量。此外在無質傳影響及氧氣限制下利用Pseudo Michaelis-Menten動力式進行分析，計算出活性濾料生物反應系統中代謝氨氣之飽和常數 (ks) 為34 ppm，最大去氨效率 (Vm) 為0.3 g-N/kg dry GAM/day，整個123天操作期平均去除效率可以達92.7%以上。停工效應 (10天) 方面，復工四天後，整個系統又恢復至原來的去除效率 (98.3%→99.2%)。本系統前半段之主要代謝物為亞硝酸根，後半段主要代謝物為氨離子。 第三部份：為縮短硫化氫惡臭氣體之處理時間及提高處理效能，本研究研發國外正發展之生化反應系統，利用化學法之高氧化特性去除硫化氫廢氣並將廢污水中篩選到之氧化亞鐵硫桿菌，將化學法之產物進行生物再生，以完成化學-生物複合反應之先導性研究。化學除硫實驗方面，固定硫化氫濃度100 ppm，氣體停留時間18秒，操作時間僅需0.5小時，去除效率即可達60%。且無論硫化氫濃度提高至200、300 ppm或降低至50 ppm，此系統皆可維持高去除率。當固定硫化氫濃度為200 ppm時，氣體停留時間超過18秒，去除率即可短時間達到85%，且無論進氣流速快慢，系統之pH變化不大。生物再生實驗方面，於40oC下，只添加亞鐵離子而無外加碳源 (Glucose) 時，亞鐵起始濃度與氧化速率呈良好之線性關係(Y=0.051X-0.01)。當系統外加0.1%碳源 (Glucose) 時，不但可增加微生物之數目，亦可提升氧化亞鐵硫桿菌代謝亞鐵之能力，反之添加過量碳源 (1% Glucose) 將出現抑制現象，此為本研究之新發現。於35oC下，微生物之代謝亞鐵速率依序為：0.1% Glucose (0.77 mM/hr) > 0% Glucose (0.45 mM/hr) > 1% Glucose (0.38 mM/hr)。當溫度降至30 oC時，仍可得到相似之代謝關係，但以35 oC時氧化亞鐵硫桿菌代謝亞鐵之速率較佳。由結果可知，化學除硫可短時間去除高濃度硫化氫廢氣，極具應用與發展潛力。考慮化學氧化反應及生物再生反應之結果，其串聯設計之規範建議如下：化學氧化反應之Fe3+濃度應可增加至15 g/l，而流速可減為50 l/hr，以增加去除率與生物系統之再生效果。生物再生反應之pH值應控制在2.0，並添加0.1%葡萄糖，以防止沉澱發生並增加硫鐵菌之再生能力，若兩者能成功結合，即可達到除臭/再生/減廢之目的。 由以上結果得知，此三套除臭模式可高效率去除不同來源硫化氫或氨氣之廢氣，生物滴濾床在長期操作過程中系統pH值穩定，濾床無酸化現象發生，溼度控制容易，壓損小且不會因操作時間長而劇增，系統操作終了，無須更換濾料。至於化學-生物複合反應系統，兩者結合之效能則需進一步進行評估。

This thesis is based on different pollutants to be designed three modes of deodorization. For this reason, the study was sorted three sections to be particularly conferred. In the first section: Autotrophic sulfur oxidizer and ammonia oxidizer, were isolated from swine wastewater and immobilized with granular activated material (GAM) to remove H2S and NH3. Due to high concentrations of H2S and NH3 could inhibit the metabolic NH3 ability of autotrophic ammonia oxidizer, but existences of H2S have no obviously influences for the metabolic H2S ability of autotrophic sulfur oxidizer. For the reason, in this study, we immobilized microorganism with GAC to form biofilm on the bead, and then packed into the pilot-scale reactor of a series connected system. The medium zone of reactor was packed autotrophic sulfur oxidize, and the end zone of reactor was packed autotrophic ammonia oxidizer to control NH3 and H2S emission. The removal character, metabolic product, removal efficiency and kinetic analysis were evaluated. The criteria for the modified biotrickling filter operation to meet the current H2S and NH3 emission standards were established. The emission of upper limits was set to reach Taiwan’s current ambient air standard of H2S and NH3. In H2S removal experiments, during the continuous operation of 210 days, the critical loading was 35 g-S/m3/h. When the maximum inlet loading of H2S was 52 g-S/m3/h, the maximum removal capacity was reached 45 g-S/m3/h. Also, kinetic analysis was derived from the Pseudo Michaelis-Menten equation, which the saturation constant and the maximum removal rate were calculated to be Ks = 29 ppm and Vm = 1.5 g-S/kg dry GAM/day. During the continuous operation of 210 days, the mean of removal efficiency can be reached 98.7%. The layoff of 10 days was no influence for H2S removal efficiency. The main metabolic product of the medium zone was element sulfur, then the main metabolic products of the end zone were sulfate and element sulfur. In NH3 removal experiments, during the continuous operation of 210 days, the mean of removal efficiency can be reached 98.4%. In removal experiments of low concentration of NH3 for long operation period, the removal efficiency can be reached 100%. The layoff of 10 days, the system of the removal efficiency was recovered from 96% to 100% after returning to work for 2 days. The main metabolic products of the medium zone were nitrite and organic nitrogen, and then the main metabolic product of the end zone was nitrite. In the second section: Heterotrophic sulfur oxidizer and ammonia oxidizer, were isolated from swine wastewater and immobilized with granular activated material (GAM) to remove H2S and NH3. Due to high concentrations of H2S and NH3 could inhibit the metabolic H2S ability of heterotrophic sulfur oxidizer, and high H2S concentration could also inhibit the metabolic NH3 ability of heterotrophic ammonia oxidizer. For the reason, in this study, we immobilized microorganism with GAM to form biofilm on the bead, and then packed into the pilot-scale reactor of a series connected system. The medium zone of reactor was packed heterotrophic ammonia oxidizer, and the end zone of reactor was packed heterotrophic sulfur oxidizer to control NH3 and H2S emission. In H2S removal experiments, during the continuous operation of 123 days, the removal efficiency of low concentration of H2S can be reached 100%. The layoff of 10 days was no influence for H2S removal efficiency. The removal efficiency can be reached 100% after returning to work. The main metabolic product of the medium zone was element sulfur, and then the main metabolic products of the end zone were element sulfur and sulfate. In NH3 removal experiments, during the continuous operation of 123 days, the critical loading was 1.37 g-N/m3/h. When the maximum inlet loading of NH3 was 10.96 g-N/m3/h, the maximum removal capacity was reached 6.5 g-N/m3/h. Also, kinetic analysis was derived from the Pseudo Michaelis-Menten equation, which the saturation constant and the maximum removal rate were calculated to be Ks = 34 ppm and Vm = 0.3 g-S/kg dry GAM/day. During the continuous operation of 123 days, the mean of removal efficiency can be reached 92.7%. The layoff of 10 days, the system of the removal efficiency was recovered from 98.3% to 99.2% after returning to work for 4 days. The main metabolic product of the medium zone was nitrite, then the main metabolic product of the end zone was ammonia. In the third section: For shortening the treatment time of H2S waste gas and improving the removal efficiency, this study develops the new system of bio-chemical reaction by overseas technology. We employ the high oxidative property of chemical method to removal H2S waste gas. Also, chemolithotrophic bacterium was isolated from wastewater, and the production of chemical method was regenerated by biological method to achieve the chemical-biological complex reaction for making a study of a precursor. In H2S removal experiments by chemical method, using inlet H2S concentration as high as 100 ppm, and the retention time as low as 18 sec, the operation time only needed 0.5 hr that the removal efficiency was immediately reached 60%. Whatever the inlet H2S concentrations were increased to 200 and 300ppm or reduced to 50 ppm, the system could all maintain high removal efficiency. Also, using inlet H2S concentration as high as 200 ppm, the retention time was exceeded 18 sec, the removal efficiency was immediately reached 85% at short-term. Regardless of the inlet flow rate was fast or slow, pH variations of the system was unapparent. In biological regeneration experiments, at 40℃, adding ferrous iron without any carbon source (glucose), ferrous initial concentration and oxidation rate presented a good linear relationship (Y=0.051X-0.01). Adding 0.1% carbon source (glucose), the amounts of microorganism were not only increased, but the metabolic Fe2+ ability of chemolithotrophic bacterium was promoted. On the other hand, adding excess carbon source (1% glucose), this study has a discovery for the inhibiting phenomenon. At 35℃, the metabolic rate of microorganism, in turn: 0.1% Glucose (0.77 mM/hr) > 0% Glucose (0.45 mM/hr) > 1% Glucose (0.38 mM/hr). When the temperature was dropped to 30℃, the same metabolic relationship was obtained. But, the metabolic ferrous iron rate of chemolithotrophic bacterium was suited at 35℃. The results of the section indicate that the chemical method can removal high H2S concentration at short-term. Therefore, the system should be a potential of application and development. Thinking about the results of chemical oxidation and biological regeneration, the conditions of series connection system were suggested as follows: the Fe3+ concentration of chemical oxidation reaction could be increased to 15 g/l, flow rate could be reduced to 50 l/h in order to increase the purposes of removal efficiency and biological regeneration. PH value of the biological regeneration reaction should be maintained 2.0, and then added 0.1% glucose in order to avoid the precipitate phenomenon and increase the regeneration ability of chemolithotrophic bacterium. If the system can make a success of combining that the study will reach the purposes of deodorization, regeneration and reducing junks. The results of the study indicate that the three modes of deodorization have high efficiency to remove H2S or NH3 waste gas from different pollutants. During long operation period, the high operation stability, no obvious acidification, easy controlling humidity, low environmental impact and low pressure drop as well as the reasonably high removal efficiency suggest that the bioreactor is a promoting technology for treatment H2S and NH3 waste gas. As for the chemical-biological complex system, we needed further to evaluate the efficiency of combining two systems.