Study On The Enriching Of Highly Efficient Degradation Bacteria Flora Of DBP And Its Degradation Characteristics

Phthalic acid esters as a plasticizer is widely applied to building decoration, cosmetics, food packaging,medical utensils, etc. As they have been used for a long time, they gradually migrated to water, soil, air and other environmental. Unfortunately, their natural degradation ability is very slow. PAEs have become a kind of persistent organic pollutants which cannot be ignored. At present, the technology of processing PAEs pollution includes physical adsorption method, chemical oxidation method, biological remediation method,etc. Adsorption method and oxidation method have the following problems, such as the regeneration of adsorbent, the expensive catalyst and so on, while the biological degradation received lots of attentions because of its high degree of mineralization, low economic cost, no secondary pollution and other advantages. Previous studies mostly aimed to screen strains in pure degradation, but in the use of bacterial enrichment are rarely studied. The bacterial enrichment has the advantage of better adaptability to the growing environment and high degradation efficiency because of the rich biological diversity.In this paper, Collection activated sludge from the wastewater aerobics treatment process pool of Kaifeng city waste-to-energy plant as sample, and select the din butyl phthalate（DBP） as the representative pollutants biological enrichment culture. The main research results are as follows:（1） A highly efficient degradation bacteria group which can be used as the sole carbon source and energy source by the enrichment culture of DBP, and named it of LV-1. Then we amplified gene fragment of the hyper variable region of bacteria V4 by primer successfully. The flora consists of 33 families, 48 genera of bacteria. Dominant bacteria are Brucella sp. and Sinobacter sp. and their relative abundancerespectively for 62.78% and 14.83%.（2） The optimal degradation conditions of LV-1 for DBP were: temperature 30 degrees centigrade,pH6.0. Under the optimum conditions, LV-1 can degrade the DBP of 500mg/L by about 93% in 48 h, and when the concentration is 1000mg/L,more than 95% DBP can be degraded in 72 h, which proves that LV-1flora is a highly efficient DBP degrading bacterium.（3） The effect on the degradation of DBP when different concentrations of six kinds of heavy metal cations, three anions, two kinds of surfactants and three kinds of exogenous carbon source have been added into the medium are studied respectively. The results showed that when the Pb²⁺, Cu²⁺, Mn²⁺, Cd²⁺, Zn²⁺and Cr⁶⁺ in the medium is at a high concentration,the DBP degradation can be inhibited significantly. While Pb²⁺, Cu²⁺, Mn²⁺ at a low concentration（50mg/L）, can promote the degradation of DBP at a certain extent.Anion aspect, different concentrations of NO_2- after accession will inhibit the DBP degradation, and when the concentration of NO_3- and SO₄^2- were at 100³00mg/L and 200mg/L, the DBP degradation ability of LV-1 can be enhanced, but when the concentration is too high or too low will also showed inhibitory effect on the degradation of DBP. Nonionic surfactant Tween-80 was able to participate in the degradation process of LV-1 at an appropriate amount, DBP in the culture medium was completely degraded. Another group of nonionic surfactant is Triton X-100, it also has obvious promoting effect on DBP degradation when it is at a high concentration. It means that the non-ionic surface active agent can effectively improve the DBP degradation efficiency of LV-1. But the anionic surfactant SDS can just inhibit the DBP degradation. Three kinds of trace exogenous carbon sources（glucose, sucrose, soluble starch） can inhibit the growth of the bacterium LV-1 partly, thereby reducing the DBP degradation efficiency, and the inhibitory effect of soluble starch was particularly significant of the three exogenous carbon sources.（4） According to the analysis of degradation products of DBP by GC-MS, combined with the study ofthe substrate range, the pathway for the degradation of DBP was speculated as: the two side chain of DBP hydrolyzed firstly, then the PA formed, the benzene ring will be opened immediately and eventually completely mineralized into CO₂ and H₂O. Degradation kinetics shows that the LV-1 requires a longer adaptation period when it was degrading the DBP at a higher concentrations, but its overall degradation ability is relatively stable, the half-life floating between 13.64¹9.2h. Substrate broad spectrum study showed that the LV-1 not only can use DBP and PA as the carbon source and energy source, but also DMP and DEP who with the short side chains. Bisphenol A, anthracene, Fluoranthene, fluorine, phenanthrene and DEHP who with the long chains cannot be used very well, naphthalene even cannot be used by LV-1basically.