Study On Simulation Experiment Of Non-process Wastewater Pretreatment In Spent Fuel Reprocessing Plant

With the greatly development of nuclear power,a large number of spent fuel factories have been established around the world.However,plenty of non-process wastewater is generated during the operation of the spent fuel plant,which makes the treatment of wastewater particularly important.Non-process wastewater mainly includes factory floor washing liquid,laundry waste liquid and bath waste liquid.And the wastewater contains a variety of pollutants,such as oil,surfactants,detergents,salts,suspended solids,etc.However,in practice,the treatment of non-process wastewater by using a single method will not achieve the expected effect.Therefore,multi-technology needs to be combined to achieve the desired effect of wastewater treatment.This paper adopts a continuous combined process of air flotation-microfiltrationultrafiltration-adsorption to treat non-process wastewater simulation liquid.Through the study of each process,the treatment effect of simulated non-process wastewater was analyzed.A continuous flotation experiment was performed on the non-process wastewater by using a selfdesigned flotation column.100 mL/min,the inlet flow rate was 30 mL/min,the COD removal rate reached 46.7 %,and the turbidity removal rate reached 72.4 %.In the membrane separation method for the treatment of simulated wastewater,the microfiltration-ultrafiltration experiment was carried out using the simulated liquid after air flotation.The results show that microfiltration experiments have a retention effect on some macromolecule organic matter and suspended matter,but a small retention effect on small molecules and ions.The optimal conditions for microfiltration are operating pressure of 0.1 MPa,feed liquid flow rate of 60 mg/L,turbidity removal rate of 1μm pore size microfiltration membrane reaches 97.0 %,and COD removal rate reaches 51.4 %.The ultrafiltration experiment has a better effect on retention of organic matter and suspended matter it is good.The optimal conditions for ultrafiltration are an operating pressure of 0.2 MPa,a feed liquid flow rate of 40mg/L,a turbidity removal rate of 99.9 %,and a COD removal rate of 88.1 %.As time goes on,the ultrafiltration membrane membrane flux decreases first and then does not change.As the operating pressure increases,the rejection rate decreases and the membrane flux increases.In the experiment of treating simulated wastewater after ultrafiltration by adsorption method,the COD removal rate of wastewater after static adsorption reached 77.45 % when the pH was 4,the equilibrium time was 5 h,and the amount of activated carbon was 1.5 g.During the adsorption experiment,through the analysis of adsorption kinetics and thermodynamics,it can be seen that the adsorption process of activated carbon conforms to the Freundlich adsorption isotherm model,and the maximum adsorption capacity is 34.84 mg/L.Activated carbon adsorption conforms to first-order kinetic characteristics,and intra-particle diffusion is one of the rate control steps.The optimal conditions for dynamic adsorption are a flow rate of 30 mL/min,absolute ethanol as the desorbent,a flow rate of 60 mL/min for the desorbed solution,COD removal rate of 93.7 %,and good dynamic desorption stability.After the combined process of air flotation-microfiltration-ultrafiltration-adsorption continuous treatment of spent fuel reprocessing plant non-process simulated wastewater,under the optimal operating parameters of each step,the turbidity removal rate reached 99.99 %compared with the original simulated liquid,COD Compared with the original simulation solution,the removal rate reached 93.69 %,and the particle size was less than 1 micron,which met the target requirements.