Research On The Treatment Of Wastewater Containing Ethylene Glycol Monomethyl Ether

The wastewater come from ethylene glycol purification section of a chemicalplant, with high organic concentration, complex chemical composition,non-biodegradable, the chemical oxygen demand (COD) attains to44200mg/L.Therefore, the wastewater must be disposed to achieve the wastewater dischargestandards. According to the domestic and foreign technology of industrial wastewatertreatments and the existing research achievements, a single treatment technology isdifficult to achieve the wastewater discharge standards. Therefore, combined processmethods will be used in this paper: firstly, solvent extraction technology was appliedto pretreat the wastewater, then Fenton reagent oxidation technology was used fordeep processing.This paper is devoted to study the optimization of solvent extraction processwhich was used to dispose the wastewater containing ethylene glycol monomethylether. The experimental results showed that the chloroform was chosen as theextraction agent and the suitable extraction conditions were:5min shake time,9times cross-flow extraction, oil-water ratio of9, pH value equal to5and ambienttemperature (25℃). The cross-flow extraction was difficult to meet the higherseparation requirements. This paper make further research on the7-stage falsecounter-current extraction. The pH value of treated wastewater equaled to1.98, CODvalue was2300mg/L, the COD removal rate reached94.80%, the BOD5value was99mg/L, get B/C=0.043<<0.3.This paper study extraction solvent regeneration experiment. By single factorexperiment to determine the optimum conditions were: when the10%NaOH solution（mass fraction） was added to30ml, chloroform recovery rate reached92.5%, theextraction result was unchanged.It indicated that this method is feasible.For the extraction wastewater was non-biodegradable, the biodegradationmethod was not suitable for the deep treatment of wastewater, so Fenton reagentoxidation was used for deep treatment wastewater. The experimental results showed that the suitable operating condition were: the mass of FeSO4·7H2O was0.18g/mL,the additive amount of H2O2was1.6mL/mL, pH value equaled to3and the reactiontime was40min. Under this condition, the COD of wastewater was19.6mg/L, theCOD removal rate was97.27%and the pH value equaled to5.6. In order to furtheroptimize the process condition, this paper has carried on the orthogonal experiment ofFenton reagent oxidation process. The results showed that four factors on the impactof COD removal rate was in the order: H2O2dosing quantity> the concentration ofFeSO4·7H2O> pH value> reaction time. The suitable operating conditions were: themass of FeSO4·7H2O was0.18g/mL, the additive amount of H2O2was1.2mL/mL,pH value equaled to4and the reaction time was50min. At this time, theremoval effect was much better. Finally, using Fenton reagent as catalytic oxidation,and under the conditions of0.18g/mL Fe2+,1.2mL/mL H2O2, pH=4, t=50min, theCOD removal rate of wastewater was as low as62.8mg/L.