Study On Degradation Characteristics Of 2,4-DCP By BES Coupled Traditional Anaerobic Reactor

Chlorophenols Compounds(CPs)is a common class of chemically stable organic compounds,mainly derived from chemical industries such as oil refining,plastic processing,pesticide production and so on.CPs are not easily degraded by microorganisms in the natural environment and will cause great harm to water bodies and soil;Moreover,it has strong toxicity and can be enriched in the organism through the food chain,causing serious damage to the activity of the organism and human health.It has been listed as a priority pollutant control by China and the United States.Based on the current research on bioelectrochemical systems(BES)and anaerobic biotechnology at home and abroad.This study takes 2,4-Dichlorophenol(2,4-DCP)as the research object,combines the BES system with the traditional anaerobic reactor,and constructs the microbial electrolysis cell-completely mixed batch reactor(MEC-CMB)system to cultivate domesticated a degradation of 2,4-DCP capacity of anaerobic sludge.A ruthenium-iridium-plated titanium mesh was used as the anode,and the cathode was made of carbon cloth to build an experimental device.The effects of the applied voltage and the initial concentration of 2,4-DCP on the degradation efficiency of the system and the degradation mechanism were studied.The following conclusions were obtained:2,4-DCP has a biological inhibitory effect on microorganisms.Through 2,4-DCP domestication,the sludge can be gradually adapted to the wastewater environment containing 2,4-DCP and has the ability to degrade 2,4-DCP.The results of multi-factor experiments show that under the condition of voltage 1.4 V,2,4-DCP initial concentration 10 mg·L-1,the coupling system can achieve 75.9%degradation rate at 24 h,which is 25.87%higher than single CMB.It had good treatment effect on low concentration 2,4-DCP.Using HPLC,HPLC-MS-MS and other methods to analyze the effluent of EMC-CMB system,it was found that the degradation intermediates mainly include o-chlorophenol,phenol,p-benzoquinone,succinic acid,etc.The main degradation pathway is 2,4-DCP?dichlorophenol?phenol?p-benzoquinone?succinic acid?malonic acid?CO2+H2O.In this project,a BES-Upflow Anaerobic Sludge Blanket(BES-UASB)coupling system was constructed,with stainless steel mesh-carbon cloth as the cathode and stainless steel mesh as the anode.Place two parallel pieces of cathode material horizontally in the UASB reaction zone,and place the anode material in the sludge sedimentation zone in the same way.Glucose is used as a carbon source to cultivate and domesticate anaerobic granular sludge.In the cultivation stage,the impact of electrical stimulation on the formation of granular sludge was investigated;in the domestication stage,the changes in the degradation performance of COD and 2,4-DCP during the domestication process were recorded;During the stable operation of the reactor,the effects of applied voltage and hydraulic residence time(HRT)on the degradation performance of the system were studied,and the following conclusions were obtained:Continuous but low-intensity electrical stimulation doesn't affect the formation of anaerobic granular sludge.Maintain a voltage of 0.5 V,gradually increase the COD influent concentration from 3000 mg·L-1 to 6000 mg·L-1,and increase the 2,4-DCP influent concentration from 0 to 40 mg·L-1.During the domestication of granular sludge,it was found that with the extension of domestication time,the concentration of sludge in the coupling system increased,the rate of degrading organic matter increased,and the degradation rate of 2,4-DCP increased by 7.7 times.Under the initial conditions of COD 6000 mg·L-1,2,4-DCP concentration of 40 mg·L-1,change the value of applied voltage and HRT.The results show that when the applied voltage is 1.2 V and the hydraulic retention time(HRT)is 72 h,the coupling system has the highest COD removal rate and 2,4-DCP degradation efficiency.