| Two kinds of high concentration wastewater are generated in the process of salicylicacid hexyl ester production. If the wastewater is treated directly with biochemicaltreatment, it will cause great harm to microbel, thus proper pretreatment beforebiochemical experiment is of great importance. In this paper, author had taken thewastewater with high concentration of hexyl salicylate production from a perfumecompany as research object and explored the best pretreatment with different methodsto meet the requirements of subsequent processing units. This study has reached thefollowing conclusions:1）The coagulant and Fenton reagent oxidation methods have been used to treatsalicylic acid hexyl ester mixed wastewater. The influent CODCrwas264089.6mg/L.The CODCrremoval rates of PAC, FeCl3and CaO coagulant were23.35%,38.34%and22.43%; relatively speaking, FeCl3coagulation is of notable effect, the variation ofCODCrhad reached100000mg/L; By the infrared spectrum comparison: FeCl3coagulation effluent absorption peak intensity was weaker. When the pH range wasbetween4.0~5.0, the dosage of H2O2was60mL/L, FeSO47H2O dosage was81.6g/L,n (H2O2): n (Fe2+)=2:1, reaction time t=0.5h, the CODCrvariation of Fenton oxidationhad reached66755mg/L and the removal rate was25.28%.2）Four methods has been carried out to study the pretreatment of salicylic acid hexylester alkaline wastewater.①The FeCl3coagulation: when pH range was between4.0~5.0, FeCl3dosage was82.5mL/L, coagulant dosage of PAM was82.5mL/L, thereaction time was10min, precipitation time was20min, CODCrremoval rate hadreached27.77%;②The CODCrremoval rate of electrocatalytic oxidation was only6.88%; But by the IR scan results analysis, electro catalytic effluent in d ifferent bandsproduced red and blue shift phenomenon, and the absorption peak intensity had changed,it showed that the organic molecular structure had changed.③The CODCrremoval rateof micro-electrolysis was8.73%.④The CODCrremoval rate of electro catalytic-FeCl3coagulation treatment had reached32.53%.3） Pretreatment experiment includes micro electrolysis, Fenton and microelectrolysis-Fenton combined with experimental methods which were used for salicylicacid hexyl ester acid wastewater treatment.①The CODCrremoval rate of microelectrolysis was12.28%;②The suitable condition for the oxidation of Fenton was: pHrange was between4.0~5.0, reaction time was2.0h, n (H2O2): n (Fe2+)=10:1, the dosage of H2O2was60mL/L and the corresponding dosage of FeSO47H2O was16.3g/L. The CODCrremoval rate was14.83%;③The CODCrremoval rate of microelectrolysis-Fenton combined method was23.44%.4）Biochemical experimental treatment influent was diluted to about13000mg/L.The amount of removal CODCrof micro electrolysis biological treatment to salicylicacid hexyl ester alkaline wastewater had reached8294mg/L and the total removal rateof CODCrwas72.78%;②FeCl3coagulation-biochemical treatment for salicylic acidhexyl ester mixed wastewater is of much better removal effect. CODCrhad decreased by7532mg/L; the total removal rate was59.63%.5）The operation results of actual project: The average CODCrconcentration valueafter FeCl3pretreatment effluent was59811mg/L. Effluent mixed with the wastewaterderived from other products, treated by hydrolysis acidification-IC anaerobicbiochemical treatment. The average CODCrof IC effluent stabled at the range of3400~3600mg/L and the average removal rate had reached94%, so as to guarantee thestability of the follow-up processing unit operation and ensure the effluent dischargedmeet the standards. Up to now, this technology has successfully treated dozens of tonshigh concentrations of salicylic acid hexyl ester wastewater which has beenaccumulated for many years by the company. |
PDF Full Text Request