發(fā)布時間：2018-12-16 23:16

【摘要】：硝基苯是苦杏仁味的淡黃色有機物,有劇毒性,易揮發(fā),密度比水大,且具有穩(wěn)定性,一旦進入環(huán)境中就很難被降解。硝基苯是一種常見的化工原料,隨著工業(yè)廢水的排放,對人體健康和水環(huán)境造成了嚴重的威脅,硝基苯已經(jīng)出現(xiàn)在多個國家或組織列出的水體優(yōu)先控制污染物的名單中,因此采用適當?shù)奶幚砉に噷⑾趸�苯徹底降�?或者將其濃度降低到國家規(guī)定排放標準是我們需要解決的環(huán)境問題之一。本實驗以硝基苯為目標污染物,以渭河西安市草灘段底泥中微生物混合微生物菌為菌種源,以硝基苯為唯一碳源,在低溫(12℃)的條件下,pH值為7,通過逐漸遞增硝基苯濃度的方式對菌種進行厭氧培養(yǎng)馴化,從馴化成熟后的馴化液中分離純化出四種硝基苯降解菌株(分別命名為W1、W2、W3、W4)。通過對4種硝基苯降解菌株篩選實驗表明,在硝基苯濃度為20mg/L,經(jīng)降解9天后,其降解率分別為84.26%、89.78%、81.66%和93.82%。通過篩選實驗得出W4菌株為硝基苯優(yōu)勢菌株。根據(jù)形態(tài)特征、革蘭氏染色、生理生化試驗結(jié)果,結(jié)合《伯爵氏細菌鑒定手冊》可初步鑒定菌株W4為和杰氏棒桿菌。在溫度為12℃的厭氧條件下,以pH值、硝基苯初始濃度、微生物接種量、不同碳源、不同氮源為影響因子對優(yōu)勢菌株W4進行降解特性研究,結(jié)果表明,菌株降解硝基苯最優(yōu)化條件是:pH為7、微生物接種量為15ml、硝基苯初始濃度為16.93mg/L;在最優(yōu)化條件對硝基苯低溫厭氧降解9天,其降解率可達到97.91%。同時通過氣-質(zhì)聯(lián)用儀對降解產(chǎn)物進行定性分析,其主要產(chǎn)物為苯胺、醛類、酮類和醇類物質(zhì),推測出可能的降解途徑是:首先硝基苯通過還原作用生成亞硝基苯、苯胺,再通過微生物合成的降解酶使得苯環(huán)開環(huán),生成低毒或無毒的醇類、酸類和酮類等有機物,最后進一步礦化為CO_2和H_2O。
[Abstract]:Nitrobenzene is a yellowish organic substance with bitter almond flavor, which is highly toxic, volatile, more dense than water, and stable. Once it enters the environment, it is difficult to be degraded. Nitrobenzene is a common chemical raw material. With the discharge of industrial wastewater, it poses a serious threat to human health and water environment. Therefore, it is one of the environmental problems that we should solve the environmental problems that we need to solve by adopting proper treatment process to completely degrade nitrobenzene or to reduce its concentration to the national emission standard. In this experiment, nitrobenzene was used as the target pollutant, mixed microorganism bacteria in the sediment of Caotan section of Weihe River as the source, nitrobenzene as the sole carbon source, and the pH value was 7 at low temperature (12 鈩，

本文編號：2383213