| Due to chromium in industrial production of a large number of applications,especially in metal and non-ferrous metal rolling etc,chromium is widely used as raw material processing,produce a large amount of industrial waste water and waste residue,due to the subsequent processing is undeserved,can’t reasonable emissions and governance,caused serious soil chromium pollution problems.This paper by jinan chromium contaminated sites in a chemical plant in the soil as the research object,use the UV/H2O2-leaching joint repair technology to remove the heavy metal in pollution soil chromium.Experiment through the single factor experiment and orthogonal experiment method,the research under the condition of different uv light intensity,ultraviolet illumination time,concentration of oxidant,earth liquid ratio,particle size and the influence of soil pH value of total chromium removal rate.According to the results of single factor experiment,the reasonable design of orthogonal experiment and optimization scheme,and according to the results of the orthogonal optimization considering repairing effect and the cost of governance,eventually determine the best experiment for different pollution status field engineering parameters.Relatively reasonable scheme of optimal parameters of performance evaluation,the following conclusions:（1）the chemical sampling points four chrome content exceeds bid badly all venues（Cr full amount 400 mg·kg-1 or less）,value of Pi（43）Pi = 26 take national quality standard,site area belong to high levels of pollution,be badly in need of governance.East the highest total chromium content in chromium slag,9703.33mg·kg-1,followed by chromate production workshop,the total chromium content is8072.75 mg·kg-1,ten thousand tons of total chromium in chromate production workshop is 7283.75 mg ·kg-1,northern factory total chromium content is the lowest,6665.87 mg·kg-1.Chromate production workshop,ten thousand tons of chromate production workshop,the north and east of chromium slag heap of factory of hexavalent chromium content were 19.43 mg ·kg-1,3.92 mg · kg-1,709.69 mg · kg-1and 449.51 mg · kg-1.Four sites activity index I have bigger difference,chromateproduction workshop and ten thousand tons of chromate production workshop of the active index is low,0.0024 and 0.0005,respectively,chromium in soil form stability,governance is difficult;The north and east of chromium slag heap factory activity index is relatively high,0.0731 and 0.0670,respectively,a small number of chromium in soil can remove by means of leaching,but the remaining total chromium content is still high.（2）the single factor experiment method is adopted to the UV/H2O2-leaching joint repair technology parameters are studied,the results show that with the increase of UV light intensity and illumination time,the growth of four sites（chromate production workshop,ten thousand tons of chromate production workshop,north east chromium slag heap,factory）of the total removal rate of total chromium are on the rise trend,but the late growth is slow,showed the ultraviolet light to H2O2 oxidation of synergy,but the effect is not obvious.Oxidant concentration maximum total chromium removal rate was 9%,four sites were 9.93%,12.64%,35.13% and 9.93%respectively.Soil liquid ratio and particle size have bigger influence on the total chromium,with the increase of liquid ratio and particle size decreases,and removal efficiency increases,the liquid ratio of 1:4 through 100 mesh sieve,four sites are total chromium removal rate were 28.66%,25.53%,52.95% and 28.66% respectively,considering the engineering operation difficulty still choose 20 mesh.PH and total chromium removal rate,the relationship between neutral and alkaline down in addition to the effect is better than the acidic conditions,pH recommended the adjusting range is pH = 8 10.Comprehensive consideration,according to the results of single factor experiment,the total chromium removal effect of the best combination is: light intensity,40 min 700 w,illumination time,oxidant concentration9%,liquid ratio of 1:4,soil particle size 20 mesh and pH = 8 10,the removal rate of total chromium was 14.53%,15.33%,46.29% and 42.72%.（3）based on the results of single factor experiment,orthogonal optimization experiment,get site for four best engineering parameters: determine the best parameters for governance of chromate production workshop: ultraviolet light 700 w,ultraviolet light time to 20 min,oxidant concentration 9%,liquid ratio of 1:4,pH =10.Total chromium removal rate reached 14.86%.Identify governance best parameters for ten thousand tons of chromate production workshop: light conditions,700 w,oxidant concentration 9%,illumination time 40 min,liquid ratio of 1:5,pH of 6.Total chromium removal rate reached 16.75%.Level of governance east chromium slag heap of best parameters for: ultraviolet light 700 w,ultraviolet light time to 20 min,oxidant concentration 9%,liquid ratio of 1:4,pH = 10.Total chromium removal rate reached 46.72%.Northern governance factory best parameters level for: ultraviolet light 700 w,ultraviolet light time to 20 min,oxidant concentration 9%,liquid ratio of1:4,pH = 10.Total chromium removal rate reached 43.66%.（4）the four sites are the best,benefit analysis,calculates the UV/H2O2-leaching joint repair technology chromium slag treatment costs per ton in 700 900 yuan,the major source of expenses for antioxidant,further confirmed that the ultraviolet auxiliary can reduce the dosage of hydrogen peroxide oxidation,reduce the management cost of technology advantage.With the traditional technique of soil restoration and chemical oxidation-leaching joint repair technology contrast,UV/H2O2-leaching joint repair technology of high concentration of chromium pollution area of governance has obvious advantages,its governance effect is better,more reasonable cost.To sum up,according to different physical and chemical properties and pollution of the situations of the pollution,comprehensive consider repairing effect and management cost,can be targeted to choose the appropriate treatment plan.The results for a chemical plant of jinan contaminated site remediation. |
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