Modified Bentonite Adsorption Biological Reaction Wall To Remove BTEX In Ground Water

With the rapid growth of the petrochemical industry, the groundwater pollution of BTEX is increasingly serious. We should research a kind of efficient and reasonable method to remove BTEX pollution in the groundwater.For our study, a series of experiments was used, the modification of bentonite for BTEX adsorption performance, as well as the modified bentonite adsorption bioreactor wall repair effect to remove the BTEX pollution in the groundwater was investigated. It quantitatively analyzed the contribution to the BTEX degradation of adsorption and biodegradation. This study also investigated the Extracellular Polymeric Substances (EPS) of microbial, which degradate the BTEX. The main results are as follows:1. The effect of BTEX adsorption of the modified bentonite was investigated. The results show that:(1) BTEX adsorption performance of the modified bentonite is better than the original bentonite, thus the modified bentonite can be used as a kind of very good modified adsorbent; (2) In the system of BTEX initial mass concentration was in the 50～250mg/L, the modified bentonite to BTEX adsorption conforms to the Langmuir and Freundlich isothermal adsorption equation, surface adsorption, based on the distribution adsorption theory; (3) BTEX adsorption of the modified bentonite was mainly physical adsorption, adsorption kinetics data can better conform to the secondary dynamics equation.2. This paper discussed how the modified bentonite adsorption bioreactor wall removed BTEX in underground water. The results showed that:(1)The modified bentonite were used in adsorption bioreactor wall. The concentration of water income had not much achieve in removing BTEX, could achieve adsorption - analytical balance.The modified bentonite could be well used as filling medium in adsorption bioreactor wall, and made it improve the removal efficiency of BTEX which was in relatively high concentrations; (2)Adsorption can make adsorption concentration BTEX in biological reaction wall greatly and rapidly reduce.The contribution rate of reduction in BTEX concentration of original bentonite and modified bentonite were 69.4% and 78.68%; (3)The degradation process in the benzene series of BTEX of microorganisms in adsorption bioreactor wall in line with the first order reaction kinetics model. Its removal rate of BTEX was ethyl benzene> toluene xylene> benzene. The degradation coefficient of benzene, toluene, ethylbenzene and xylene in Unit 1 and unit 2 were 0.076 and 0.139,0.127 and 0.306,0.534 and 0.873,0.120 and 0.436. The using of modified bentonite for the promotion of degradation coefficient of the benzene series matter were 0.063,0.179,0.339,0.063. It had the minimum promotion efficiency in benzene and the largest in ethyl benzene.3. Based on the experiment of EPS extraction of BTEX degradation bacteria for three-dimensional fluorescence and infrared spectrum, it can be seen that EPS contributes to BTEX adsorption, for its important role in the biodegradation.The modified bentonite adsorption permeable reactive barrier has good effect to eliminate BTEX in groundwater, has the certain reference significance to remediate BTEX in the groundwater pollution.