以含有固定化硫化菌及氨氧化菌之流體化床式生物反應器去除硫化氫及氨氣

Abstract

將異營性硫化菌Pseudomonas putida 及異營性氨氧化菌Arthrobacter oxydans分別以褐藻膠鈣固定化後，將此固定化膠體填充於流體化床式生物反應器中進行硫化氫及氨氣之去除實驗，並探討其去除特性、代謝產物、及去除效率。在硫化氫之去除實驗中，當硫化氫濃度為10-110 ppm、氣體流速為36 l/hr以下時，硫化氫的去除效率可超過95%。而此單一進氣系統最大去除效率為Vm=7.0×10-8 g-S/cell/day，飽和常數為Ks=76.2 ppm。此系統主要之代謝產物為元素硫。由於元素硫之產生不會造成系統的酸化，且具經濟價值，因此在應用上極具潛力。而氨氣去除實驗中，在低流量(27 l/h)下，100 ppm以內之氨氣其去除效率可達90%以上。其主要之代謝產物為亞硝酸氮。而此單一進氣系統，氨氣之最大去除效率Vm=1.88□10-6 g-N/cell/day，飽和常數Ks=30.5 ppm，相較於固定式生物反應器有更小的Ks值，表示在此系統中Arthrobacter oxydans對氨氣有很好的親和力。此外，本研究亦將異營性硫氧化菌Pseudomonas putida 及異營性氨氣菌Arthrobacter oxydans 予以共固定化，同時進行硫化氫及氨氣的去除實驗。結果顯示，5-60 ppm之硫化氫並不會抑制Arthrobacter oxydans代謝氨氣之酵素活性。但60 ppm之氨氣則會抑制Pseudomonas putida之酵素活性。而且，此生物反應器所溢散出的生物氣膠量，較傳統式生物濾床少，因此，此共固定化系統不但可同時去除兩種污染物質，極具經濟可行性，且對環境的衝擊將可降至最低。

Heterotrophic Pseudomonas putida and Heterotrophic Arthrobacter oxydans were immobilized with Ca-alginate to form bioactive beads, and then were packed in the fluidized-bed biofilter system. The removal efficiency and capacity for H2S and NH3 were evaluated. The effect of operating parameters, included pH value, phosphate concentration, and inlet gas concentration, on the removal efficiency and capacity was evaluated. In the hydrogen sulfide removal experiment, the system exhibited high H2S removal efficiency(in excess of 95 %)at H2S concentrations from 10 ppm to 110 ppm and flow rates below 36 l/h. The maximum removal rate(Vm)and the saturation constant(Ks)were determined 7.0□10-8 g-S/cell/day and 76.2 ppm, respectively. Hydrogen sulfide was mainly converted to elemental sulfur, which can be reused. Thus, immobilized P. putida biofilter appears to be a promising method to treat H2S emissions. In ammonia removal, 90% of NH3 removal efficiency was reached at initial concentrations of NH3 less than 100 ppm and flow rates below 27 l/h. Ammonia was mainly converted to nitrite-N. The maximum removal rate(Vm)and the saturation constant(Ks)were calculated as 1.88□10-6 g-N/cell/day and 30.5 ppm, respectively. Compared to fixed-bed biofilter, the fluidized-bed biofilter has smaller Ks value. Heterotrophic P. putida and A. oxydans were also co-immobilized to remove H2S and NH3 from waste gases simultaneously. The results showed that the H2S removal efficiency of the biofilter was significantly affected by high concentrations of NH3(60 ppm). On the other hand, NH3 removal efficiency of the biofilter was not affected by H2S concentrations(5-60 ppm). The amount of bioaerosol generated was less than that of the traditional biofilter. Therefore, employing immobilized cell technology can cause less environmental impact and higher operational stability.