The Response Mechanism And Application Research Of Energy Metabolism In BTEX Microbial Degradation

Benzene Toluene Ethylbenzene and Xylene(BTEX)is a kind of organic substance with highly toxic.Microbial degradation plays a key role in the natural attenuation of BTEX.However,the existing method like material concentration,microbes,and compound-specific isotope analysis are difficult to monitor,assess the microbial degradation type and stage of natural attenuation comprehensively.Energy is one of the state variables which through the microbial degradation process,which interwoven with the substance transformation,and Interpret the microbial degradation from a new perspective.However,the relevant research is limit at present.Therefore,this thesis focusd on the natural attenuation of BTEX,developed the applicable testing techniques for microbes'energy indexes in groundwater,built the substance-energy coupling model,establish the energy metabolism index correlated with the substance transformation,carried out the new model and index in laboratory simulation experiment and field application,study and reveal the response mechanism of energy metabolism in the microbial degradation of BTEX.The main results are as follows:(1)Considering the low ATP(adenosine triphosphate)content and easy transformation of groundwater microorganisms,the laboratory HPLC detection technology with hot water pretreatment method,could detecting ATP,ADP(adenosine diphosphate)and AMP(adenosine monophosphate)at the same time,the detection limit was 0.1 ppm,the fluorescence testing technology for field could also test ATP,ADP and AMP,and the detection range was from 5×10^-4to 50 ppb,and do not need pretreatment for the energy detection of groundwater microorganisms(2)Based on the principle of substance transformation and energy metabolism,the substance-energy coupling model was built.The equation is as follow:-(1/2)*d[ATP]/dt+(1/2)*d[ADP]/dt+d[AMP]/dt-0.65*[ATP]/(100+[ATP])=dc_i/dt(c_i is the substance transformation index).The relationship between substance transformation and energy metabolism of groundwater microorganism was modeled for the first time.Then,the new index of substance transformation correlated adenylate(STCA)was established.The eqution of STCA is(1/2)*(1nADP-1nATP)+1nAMP.This index can reduce the dimensionality of the single energy metabolism indexes and correspond well with the substance transformation indexes.(3)Different types of microbial degradation could be distinguished by the change and the cumulative probability curve of electron donor and acceptor indexes(COD?DO?NO₃^-)with time or distance parameters.In each degradation type,lnATP can be used to distinguish different degradation stages(lag phase,log phase,stationary phase,decline phase)with the change of time or distance parameters.(4)Under different degradation stages of oxidation and denitrification,there was a good linear correlation between the energy metabolism indexes STCA and lnAP and the substance conversion index COD,COD is a representative indicator of BTEX organic pollutions in groundwater sites,which proved that there was an excellent response mechanism between the energy metabolism indexes and organic pollution indicator.The study on the microbial population structure of the contaminated site showed that the unclassified_f<sub>Alcaligenaceae was the most widely distributed species in all the samples,and had a significant correlation with COD,STCA and lnAP,which could be used as a microbial indicator of the energy metabolism.In conclusion,this study could provide new technical methods and theoretical support for the research and application of natural attenuation,risk assessment and comprehensive control in groundwater organic pollution.