Hydraulic Control And Numerical Simulation In Remediation Of Chlorinated Organic Pollution Groundwater

Now groundwater contamination is one of the most serious environmental problems all over the world. Groundwater pollution remediation is a research hotspot at home and abroad. Whether in-situ remediation or ex-situ remediation, the key point is groundwater hydraulic control. Numerical simulation which used to describe time-space characters of migration and transformation rules of contaminants in groundwater will support theory base for treatment and control of contamination. So, it is important and has theoretical and practical significance to study hydraulic control and numerical simulation of groundwater.In order to study the groundwater hydraulic control, a small scale porous aquifer model was constructed by using tank with silica sand in the laboratory. It is used to study solute transport characteristics in the aquifer at different hydraulic conditions by tracer test. Four tracer tests have been carried out in the porous aquifer, including two nature flow field tracertests having different hydraulic gradient and two man-controlled flow field tracer tests having different flow value. The man-controlled groundwater flow is controlled by a recirculation system of pumping and injecting water. Select Cl-as a representative inorganic substance. The experimental results show that the change of hydraulic gradient has an effect on solute transport and the control of flow field makes solute intercept come true.The groundwater system and the solute transport of model aquifer were numerically simulated by a groundwater modeling software (GMS). We set different boundary conditions for the four tracer tests. Firstly, we simulated stable flow field, then performed the parameter sensitivity analyses and discussed the affection of parameters. Next, we simulated the solute transport in groundwater by using Cl-as a tracer, and made parameter sensitivity analyses too. The results show that numerical modeling results indicated a good match with computed and observing data, so we can use the model to design detailed parameters for pump and treat method and predict the restoration conditions and effects. The parameter sensitivity analyses for pump-and-treat show that the factors of influence for hydraulic control of groundwaterare longitudinal dispersion, porosity and hydraulic conductivity in descending order.Combining with experiments and numerical simulation, we studied the transport of TCE in the aquifer and used the pump-and-treat method to TCE restoration. The experiment of migration for TCE indicates that TCE has obvious hysteresis effect. During pumping operation, TCE plume and concentration both have net reduction. Aftertreatment TCE has slight rebound.Finally TCE remediation efficiency (RE) reached85.5%. The results show that pump-and-treat technique has a good effect on remediation of chlorinated organic pollution groundwater.