| Phthalate acid esters (or Phthalate esters, write PAEs for short)industrial compoundsof endocrine disrupting chemicals,because of its hazards and potential toxicity to thehunmanit belongings to priority pollutants of United States Environmental ProtectionAgency andChina’s priority pollutants of environmental pollution control blacklist.Europe, the United States, Japan and other developed countries strictly limit the use ofphthalates, andthey have clear laws and regulations.In our country the phthalate(2-ethyl-hexyl) ester islimited8μg/lin the standardsfor urban water supply and standardsfor drinking waterquality.In recent years, the detection rate of the PAEs of in Chongqingarea source water increase, it is a potential threat to the safety of drinking water.Therefore, in order to remove the PAEs of drinking water, reaearching an effective andreliable treatment process has important significance to eliminate the potential risk ofendocrine disrupting chemicals and ensure the safety of water supply in chongqing area.Regarding DMP, DBP and DEHP which represent the PAEs as the objects, thepaper based on the pilot plant, research the removal efficiency of PAEs in chongqingareasource water by the conventional treatment process and the activated carbonadvanced treatment process. At the same time, the theory adsorption properties ofactivated carbon for three PAEs are aesearched.The resultsof the pilot-scale simulated conventional treatment process showsthattheremoval rateof conventional indicators on the Yangtze River source water arehigh by the grid flocculationinclined lamellar precipitation and sand filtrationprocess.When the dosage of DMP, DBP or DEHP is about100μg/l, the removal ratesare15.01%,21.76%and13.53%. When the initial dosing concentration of the PAEs isincreased, the conventional process removal rate is reduced.The study onthe theory adsorption properties of activated carbon shows that thecoconut based carbon,the wood based carbon andthe coal based carboncan effectivelyadsorb DMP, DBP and DEHP, and the Adsorption model morefit the Freundlich model.On the same adsorption condition, the adsorption capacity of DMP and DBP is greaterthan DEHP. The adsorption kinetics testresults indicate that the adsorption of DMP,DBP and DEHP by the coconut based carbon follows the first-order kinetics.The adsorption coefficient of three kinds of PAEs are0.05605,0.03226and0.01872.Whenincreasing the speed is increased, the adsorption coefficient of DBP is increased. Usingthe activated carbon to remove the PAEs is feasible.Activated carbon treatment of PAEs in the pilot test indicates that it has norelationship between the selected site and the amount of powdered activated carbon, inadditio the selected site also has no connection with the initial concentration of PAEs. Itis suggested that the best removal rate is achieved at the raw water intake. The removalrate of PAEs is increased with the decreasing of initial concentration of PAEs. When theInitial concentration of DEHP is20μg/l and the PAC dasage is20mg/l, the efflent ofDEHP is7.19μg/l, meet the requirements of national standards. Dosing PAC has goodtreatment effect has good treatment effect in the case that the initial concentration ofPAEs is not very high. In the granular activated carbon column test, at the filtration ratefor the8m/h, the initial concentration of PAEs in the20μg/l, the efflent of DEHP is6.47μg/l, meet the requirements of national standards. The initial concentration of PAEsin the50μg/l and100μg/l, the removal rate of PAEs is between64.40%to91.38%.Theremoval rate of DBP and DMP is higher than the DEHP. Activated carbon treatmentprocess can effectively remove PAEs. |
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