Study On Simultaneous Removal Of The Phenol And Oil From Coal Gasification Wastewater By Pervaporation

Coal gasification wastewater contains large amounts of organic pollutants such as phenol and oil,which seriously endangers the health and living environment of humans.At present,extraction and air flotation are mainly used technologies to remove phenol and oil from coal gasification wastewater in industry.However,the traditional oil removal technologies cannot remove emulsified oil and dissolved oil,which will be absorbed in pipelines and block the pipeline in the following ammonia treatment process.And using the membranes which possess strong affinity to organics,as separation membranes,emulsified oil,dissolved oil and phenol can be removed by pervaporation.In this paper,homogenous membranes A were prepared using A as polymer,A/B composite membranes were prepared using B membrane as support layer.The membrane were characterized by scanning electron microscope(SEM),X-ray diffraction(XRD).Then,simultaneous removal of phenol and oil from coal gasification wastewater was studied,and the effects of the parameters including feed concentration,operating temperature,feed circulation flow,and membrane thickness on pervaporation performance were investigated in detail.Based on data getting in the experiment,the simulation coal gasification wastewater treatment process was carried out,and by the simulation,the cost of the treatment of the wasterwater was got.The specific results are as follows:1.Using the homogenous membranes A as separating membrane in pervaporation experiments,the effect of the parameters including the operating temperature(30-50°C),feed concentration(phenol 0.03-0.54 wt%,oil0.0067-0.12 wt%),feed flow(10-80 L/h)and membrane thickness(40-120?m)on pervaporation performance were investigated.The results show that the largest permeation fluxes of phenol and oil are 12.73 g/(m~2·h)and 6.63 g/(m~2·h),and the corresponding separation factors are 14.19 and 32.52,respectively,under the condition that the temperature is 50°C,the flow is 80L/h,and the membrane thickness is 40?m.2.Using the composite membrane A/B as separating membrane,under the similar experimental conditions to the homogenous membrane A,with the operating temperature range of 30-80°C,and membrane thickness from 20?m to 100?m,the pervaporation process was investigated.The results show that the largest permeation fluxes of phenol and oil are 124.15 g/(m~2·h)and 57.58g/(m~2·h),and the corresponding separation factors are 20.03 and 39.67,respectively,with the temperature of 80°C,the flow of 80L/h,and the active layer membrane thickness of 20?m.Under this condition,and with the membrane area of 100 m~2,it takes about 1.62 h with 170.06 kg penatrating liquid to lower the concentration of the oil and phenol in 1 t coal gasification wasterwater(phenol 0.54 wt%,oil 0.12 wt%)until it reached the discharge standard.3.Based on the results obtained in the pervaporation process with both membrane A and membrane A/B as separating membrane,It comes to the conclusion that the permeation flux increases with the increase of the feed concentration,in contrast,the separation factor decreases with the increase of the feed concentration.With the increasing of the operating temperature and feed flow,both the permeation flux and the separation factor increase.The permeation flux decreases with increase of the membrane thickness while the separation factor increases.4.The technological process was designed based on the data getting in the above mentioned experiment.By the process,the cost of treating the coal gasification wastewater(1t/h)was calculated and it is 2.2 yuan,which is absolutely lower than that 15.1 yuan by the extraction process currently used in industry.