| The coking wastewater is acknowledged as one of the high concentration organic industry wastewater of difficult processing.The present technology of coking wastewater treatment is mainly restricted by the problem of effluent water,equipment and operating cost,and secondary pollution.Membrane separation technology with high efficiency,low operating cost and no secondary pollution,shows a broad application prospect in the field of wastewater treatment.So,it is an important solution of the coking wastewater treatment to apply the membrane technology with the ultra-filtration as a core to handle the coking wastewater.This also lays a certain research foundation for the application of membrane technology in the field of high concentration organic industry wastewater.In this paper,PES was chosen as membrane material.Considering the research purpose was to improve the hydrophilia and antifouling of membrane,PEG-TiO2-PES blending membrane was prepared with PEG-TiO2 blend system as an addictive by the blending method.The modification effects of PEG mass concentrations on membrane properties were studied.The results showed that the PEG mass concentration had a greater influence on rejection rate but had an unconspicuous improve effect on the hydrophilia and water flux of membrane.The optimal PEG mass concentration of0.25wt%was determined by the comprehensive evaluation method.When the effluent coking wastewater in secondary settling tank was filtered with such membranes,the water flux was not high but the COD rejection rate was very high,indicating that such membranes had a certain prospect in the coking wastewater treatment.Then,in order to further improve the hydrophilia and water flux of membrane under the condition of guarantying the rejection rate,the PVA was used as composite membrane material and coated on the 0.25wt%PEG-TiO2-PES blending membrane with the glutaraldehyde as the cross-linking agent to prepare the PES/PVA composite membrane.The effects of PVA concentrations and cross-linking time on membrane properties were studied.The results indicated,within the range of study,the prepared composite membrane had stronger hydrophilia,larger water flux and higher rejection rate when the PVA concentration was 3wt%and the cross-linking time was 6h.At the moment,the contact angle declined from 65°to 50°,the water flux and COD rejection rate were respectively about166L/m2·h and 89%.Finally,the 0.25wt%PEG-TiO2-PES blending membrane and PEG-TiO2-PES/PVA composite membrane were applied into the COD desorption of the high concentration coking wastewater with the CODcr value of 4448mg·L-1 in the balance tank.The results showed that both the modified membranes could be applied into the treatment of coking wastewater and their flux recovery was above 80%.However,the PES/PVA composite membrane exerted better hydrophilia and stronger antifouling property than PES blend membrane,thus it was more suitable for the COD desorption of high concentration coking wastewater and the PES blend membrane could be used in the low concentration coking wastewater treatment. |
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