Experimental Study On Oxidation Of Petroleum Pollutants In Groundwater Flow Field

Leakage occurs during petroleum development,storage,transportation,and refining.The leakage of petroleum substances on the surface into the groundwater system through atmospheric precipitation,soil leaching and other ways,resulting in a large number of petroleum hydrocarbons into the groundwater system caused by groundwater pollution,seriously endangering the safety of the groundwater environment.In order to repair the polluted groundwater environment and make it return to its original state,and to get a kind of technical method which can be used in practical engineering to restore the petroleum-bearing groundwater,this project constructed the push-flow diffusion model in the groundwater flow field,studied the characteristics of ferrate oxidant diffusion and transport with groundwater runoff,and combined with PRB technology simulated the oxidation degradation of petroleum wastewater in groundwater through experimental model reaction column.The research results show:(1)In the experimental oxidation column model,the transport and diffusion of ferrate oxidants and the oxidation of petroleum pollutants are similar to the general cylindrical thrust reactor,the oxidation reaction is accomplished in a constant state,and in complete mixing,oxidant ferrate oxidation under unsteady state decomposition characteristics of the petroleum contaminants.(2)The length of the experimental oxidation column model(L=11.1m)and the time for completing the oxidation reaction(T=26h)are the same as the time for the oxidation test to complete the oxidation process.Therefore,under the experimental conditions of the oxidation column model,the transport and diffusion process of the simulated groundwater flow field can meet the mass transfer conditions of the oxidative decomposition of petroleum pollutants by ferrate oxidants.The removal rate of petroleum substances in wastewater by PRB modelreaction column can reach 74%~85%.After treatment,the petroleum concentration can reach the IV water quality standard.(3)As in the fully mixed state oxidation test,the product of the oxidation reaction(Fe(OH)3)consumes alkalinity,resulting in a drop in pH under the conditions of each influent concentration in the experimental oxidation column model.However,due to the presence of the carbonate buffer system,the pH can be stabilized above 7.1 until the reaction is complete,and the buffer range is not exceeded.(4)During the operation of the test model,no obvious changes in material transport and diffusion characteristics caused by filling medium blockage were observed.The prediction of pore clogging time shows that the clogging time is much longer than the time required for potassium ferrate combined with PRB to repair groundwater,ensuring stable operation of the groundwater environment system.