| Because activated carbon has advantages of large capacity of absorption,simplicity of operation and steady treatment effect,activated carbon adsorption as advanced treatment always be used to treats pharmaceutical wastewater,which contains pollutants that are complex and diffucult to biodegraded.If saturated activated carbon is not disposed properly,it will damage ecological environment when it goes into environment.Not only could microwave-ultraviolet regeneration regenerate activated carbon,but also remove pollutants.However there are high regeneration cost and limited regeneration rate.At the same time,it will cause the large loss of activated carbon that microwave-ultraviolet regeneration needs being operated under aerobic condition.This study used a mixture of activated carbon and expanded graphite as adsorbates to treat pharmaceutical wastewater and saturated adsorbents were regenerated by microwave-ultraviolet radition.This way has the features of high regeneration rate and low adsorbent regeneration attrition rate.Based on the component and quality analysis of pharmaceutical wastewater and adsorbents preparation,this study took adsorption amounts and removal rate of COD as indexes to evalucate of adsorption capacity.The paper studied the effects of different pretreatments to adsorption,such as the amount proportion of expanded graphite,p H,temperature and time.And it further explored the adsorption mechanism of adsorbents.The results showed acid condition and low mass proportion of expanded graphite was advantageous to the the adsorption of pollutants by compound adsorbent.adsorption By contrast of another temperature,quantity of COD and removal rate of COD by P-G 15 reached a peak at 25?.After 15 min,the adsorption approached saturation point.The adsorption process,which P-G 15 adsorbed pollutants in pharmaceutical wastewater,was exothermic and spontaneously order.And it followed Freundlich model.Its kinetics model was realitively consistent with the second-order equation.Using microwave-ultraviolet technology as regeneration method to regenerate adsorbants,this study took regeneration rate of COD and attrition rate of adsorbents as indexes to evalucate of regeneration capacity.This paper studied the effects of different pretreatments to regeneration,such as the amount proportion of expanded graphite,the amount of adsorbant,microwave power,radition time,electrode-less ultraviolet lamp and regeneration times.Further more,it explored the adsorption mechanism of regenerated adsorbents and the gas product of different regeneration method.The orthogonal experiment results showed the optimum regeneration condition.The optimum regeneration condition was that 5g of activated carbon mixd with 15wt% expanded graphite(P-G 15)were regenerated under 500 W microwaveultraviolet radition for 60 s.P-G 15's regeneration rate of COD,after 5 regeneration times,was 90.36% which was higher than activated carbon's,but its attrition rate was lower than activated carbon's.The adsorption process,which regenerated P-G 15 adsorbed pollutants in pharmaceutical wastewater,follows Freundlich model.And cost analysis had been calculated under the optimum condition to regenerate P-G 15. |
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