短链氯化石蜡(SCCPs)在2017年被定义为持久性有机污染物,它们可以在环境中迁移和转化,在生物体中积累,并通过食物链进行扩增。尽管它们对环境安全和人类健康构成严重威胁,关于他们被移除的文件很少。目前的SCCP去除方法价格昂贵,需要苛刻的操作条件,涉及耗时的生物治疗,去除特异性差。因此,寻求有效的方法来清除短链氯化石蜡是很重要的。在本文中,引入了一个加压反应器,研究了大肠杆菌菌株2对短链氯化石蜡的去除性能。结果表明,适度的纯氧加压促进细菌生长,但是当它超过0.15MPa时,细菌生长受到严重抑制。当短链氯化石蜡浓度为20mg/L时,0.15MPa纯氧加压7天,短链氯化石蜡去除率为85.61%,比大气压下高25%(68.83%)。相比之下,0.15MPa气压下的去除率仅为69.28%。随着压力继续增加,短链氯化石蜡的去除率明显下降。随着压力的增加,胞外聚合物(EPS)的总量显着增加,紧密结合EPS(TB-EPS)的量高于松散结合EPS(LB-EPS)。压力主要促进LB-EPS中蛋白质的分泌。此外,适当的纯氧压力为0.15MPa可提高脱氢酶活性。气相色谱-质谱(GC-MS)结果表明,该降解途径可能涉及短链氯化石蜡中C-Cl键的断裂,产生Cl-,其次是C-C键断裂。该过程将长链烷烃降解为短链烷烃。此外,主要降解产物为2,4-二甲基庚烷(C9H20),2,5-二甲基庚烷(C9H20),和3,3-二甲基己烷(C8H18)。
Short-chain chlorinated paraffins (SCCPs) were defined as persistent organic pollutants in 2017, and they can migrate and transform in the environment, accumulate in organisms, and amplify through the food chain. Although they pose a serious threat to environmental safety and human health, there are few papers on their removal. The current SCCP removal methods are expensive, require severe operating conditions, involve time-consuming biological treatment, and have poor removal specificities. Therefore, it is important to seek efficient methods to remove SCCPs. In this paper, a pressurized reactor was introduced, and the removal performance of SCCPs by Escherichia coli strain 2 was investigated. The results indicated that moderate pure oxygen pressurization promoted bacterial growth, but when it exceeded 0.15 MPa, the bacterial growth was severely inhibited. When the concentration of SCCPs was 20 mg/L, the removal rate of SCCPs was 85.61% under 0.15 MPa pure oxygen pressurization for 7 days, which was 25% higher than at atmospheric pressure (68.83%). In contrast, the removal rate was only 69.28% under 0.15 MPa air pressure. As the pressure continued to increase, the removal rate of SCCPs decreased significantly. The total amount of extracellular polymeric substances (EPS) increased significantly upon increasing the pressure, and the amount of tightly bound EPS (TB-EPS) was higher than that of loosely bound EPS (LB-EPS). The pressure mainly promoted the secretion of proteins in LB-EPS. Furthermore, an appropriate pure oxygen pressure of 0.15 MPa improved the dehydrogenase activity. The gas chromatography-mass spectrometry (GC-MS) results indicated that the degradation pathway possibly involved the cleavage of the C-Cl bond in SCCPs, which produced Cl-, followed by C-C bond breaking. This process degraded long-chain alkanes into short-chain alkanes. Moreover, the main degradation products detected were 2,4-dimethylheptane (C9H20), 2,5-dimethylheptane (C9H20), and 3,3-dimethylhexane (C8H18).