| The municipal solid waste incineration method is widely used as a kind of garbage disposal method.The fly ash produced in the process is highly toxic due to its enrichment of heavy metals,which poses a threat to the environment and human health.Electric removal method is a kind of method which can effectively deal with heavy metals in fly ash from municipal solid waste.The three-dimensional electrode method has more efficient mass transfer ability than traditional two-dimensional electrode method,which can improve the current efficiency and make the removal effect better.In this paper,the incineration fly ash from a waste incineration plant in Chongqing was selected as the research object.The experimental study on the electric removal of heavy metal contaminants from waste incineration fly ash was carried out to explore the effective effect of a fly ash to obtain more effective harmless treatment method.Firstly,the physical and chemical properties of incineration fly ash are analyzed,and the following conclusions can be drawn: Zn,Pb,Cd,Cu and Mn are the main heavy metals in incineration fly ash.The contents of heavy metals in incineration fly ash were Cu 691 mg / kg,Zn 5604 mg / kg,Pb 1822 mg / kg and Cd 321 mg / kg,respectively,which exceeded the soil environmental standard(GB15618-2008 draft)Of the residential land two standard.The leaching toxicity was Cu 1.418 ?g / mL,Zn 23.412?g/ mL,Pb 1.922 ?g / mL and Cd 1.326 ?g / mL,respectively,and Pb and Cd exceeded the standard value of pollution control of domestic landfill.The electromagnetism removal experiment was designed with a single factor experiment with the specifications of the particle electrode(? 3mm×4mm,?4mm×4mm,?5mm×5mm,?5mm×6mm,?6mm×6mm).The dosing ratio(5%(4.5%,15 V,9V,18V),repair time(5d,10 d,15d)as the main design index.A set of L9(34)orthogonal experiment was designed by calculating the removal rate of heavy metal leaching toxicity In order to obtain the optimal experimental conditions for removing heavy metals from fly ash by three-dimensional electrode method.It can be concluded that the grain size of graphite particles has a significant effect on the removal of Cu,Pb and Cd in the single factor experiment.When the particle electrode size is chosen as?6mm×6mm,the removal efficiency of Cu and Pb is the best,Cd in the particle electrode specifications for the ?4mm×4mm to achieve the best removal effect,and the appropriate increase in the surface area of the particle electrode,making the currentcontact point increases,which led to the resistance between the particles to reduce the system current to strengthen,so that the removal effect,Solid selection of ?6mm×6mm for the best experimental particle electrode specifications.The average removal rate of leaching toxicity of four heavy metals Cu,Zn,Pb and Cd was 89.05%,90.51%,50.38% and 82.56% respectively,and the average leaching toxicity was 0.155?g/mL.The average leaching toxicity of four heavy metals Cu,Zn,Pb and Cd was 2.221 ?g/mL,0.954 ?g/mL and 0.231 ?g/mL.Through the analysis of variance of heavy metal removal rate,the optimal experimental parameters were 5% for the particle electrode,9V for the repairing voltage and 5 days for the repair time.By three-dimensional electrode method and two-dimensional electrode method,the removal rate of leaching toxicity in Cu-element traditional two-dimensional electrode experiment was 53.44% under the same condition of all other experimental conditions,and the leaching toxicity was obtained in the electric electrode removal experiment.The removal rate of up to 89.66%,much higher than the traditional electric removal experiment,Cd element and Zn element of the three-dimensional electric removal method is also much higher than the two-dimensional electrode electric removal method.In the electrolysis process,the voltage applied at both ends is kept constant,then the three-dimensional electrode method than the traditional two-dimensional electrode method to increase the current generation,resulting in heavy metal precipitation increased. |
PDF Full Text Request