自營性嗜氫菌菌種分離及其在廢水中脫硝除硫效能之研究

Abstract

化工及製藥廠廢水和垃圾掩埋場滲出水中常含有高濃度的硝酸鹽和硫酸鹽，若不妥善處理將會衝擊人類健康與造成環境危害。厭氧環境下可脫氮除硫之自營性嗜氫菌作為處理菌種，由於其對碳源需求低，短時間內即有良好的硝酸鹽及硫酸鹽去除效果，雖然對於水中脫硝及除硫的自營性嗜氫菌研究很多，但不同氮及硫比例對於自營性嗜氫菌處理硝酸鹽及硫酸鹽效果和影響與具有脫硝除硫能力之菌種則不甚清楚。因此，本研究由生物厭氧污泥中以抹碟及劃碟方式篩選出具脫氮除硫作用之單一自營性嗜氫菌菌落，並將此單一菌株與混合菌群作脫氮除硫效率之比較，探討不同硫及氮的比例對脫氮除硫效率之影響。本研究從反應槽中分離出 Methyloversatilis universalis 和 Pseudoxanthomonas japonensis 兩種短桿狀菌株及 Flavobacterium psychrophilum 長桿狀菌株共三種微生物，結果顯示此三種純菌皆具有脫硝及除硫的能力。在脫硝方面以 Flavobacterium psychrophilum 具有最佳脫硝效果，脫硝率達 87.8%;在除硫方面以 Pseudoxanthomonas japonensis 具有較佳的除硫能力，除硫率達 65.6%。混菌方面，脫硝率及除硫率在 36 小時內可分別達到 93%和 60%的去除效果。當水體中含有殘餘硝酸鹽未被去除時，不論殘餘硝酸鹽濃度高低，自營性嗜氫菌系統混菌除硫效能皆明顯受到抑制。因此，自營性嗜氫菌雖具有脫硝及除硫的能力，但其脫硝及除硫的效果與廢水中硝酸鹽濃度有關。

Chemical and pharmaceutical wastewaters, and landfills leachate often contain high loading of nitrate and sulfate. The high concentration of nitrate and sulfate will affect our health and cause environmental damage if we can’t process them properly. Autohydrogenotrophic bacteria, possessing a removal capacity for nitrate and sulfate, have low carbon demand and addicted hydrogen to be electron donors. In addition, its performance for removal of nitrate and sulfate is very well in short period of time. Although there were many studies on the denitrification and sulfate reduction of autohydrogenotrophic bacteria, the effect of different nitrogen and sulfate ratio on denitrification and sulfate reduction and the autohydrogenotrophic bacteria community are still unclear. This study aims to isolate of autohydrogenotrophic bacteria, as well as to investigate the effect of nitrogen and sulfate ratio on the nitrate and sulfate removal efficiency. The results showed that Methyloversatilis universalis, Pseudoxanthomonas japonensis, and Flavobacterium psychrophilum were isolated from our lab-scale autohydrogenotrophic bacteria anaerobic bioreactor. For isolated strains, the nitrate removal rate of Flavobacterium psychrophilum was 87.8% and the sulfate removal rate of Pseudoxanthomonas japonensis was 65.6% in 72 hours. For mixed culture, the nitrate and sulfate removal rate were found at 93% and 60% respectively. The effect of sulfate reduction of mixed culture on different nitrogen and sulfate ratio would be inhibition when nitrate was residual in the aqueous solution. Overall, autohydrogenotrophic bacteria have ability for both denitrification and sulfate reduction, of which performance would be affected by the amount of nitrate in the aqueous solution.