基于气泡理论分析表面活性剂对微孔曝气增氧性能的影响
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摘要
在污水处理厂、湖泊、水库、河口和养殖池塘等需要曝气增氧的水体中,通过增氧机来维持水体溶解氧的动态平衡是非常重要的。而生活污水、城市废水等水体中常常会存在有表面活性剂,当这些废水进入以上需要曝气增氧的水体时,势必影响微孔曝气系统的增氧性能和传质效果。因此,为了探究表面活性剂对微孔曝气系统增氧性能的影响,在长2 m、宽0.8 m、高0.8 m的试验水池中,以固定于水池中央的微孔曝气盘为增氧机,根据美国土木工程协会(ASCE)标准增氧试验方法,以阴离子表面活性剂,即十二烷基苯磺酸钠为影响因子,在5种曝气流量和阴离子表面活性剂浓度下进行了一系列的水体底部微孔曝气增氧试验。基于氧体积传质理论和气泡理论,计算分析了水体氧体积传质系数、气泡的Sauter平均直径和波形因子等参数,结果表明:在一定的曝气流量下,1 mg/L的阴离子表面活性剂提高了水体的氧体积传质系数,促进了氧传质;在阴离子表面活性剂浓度为1~5 mg/L时,随着浓度的增加,氧体积传质系数降低;而且阴离子表面活性剂使气泡的Sauter平均直径降低,降低率达到22.76%;在水体无表面活性剂的试验中,气泡的波形因子变化幅度较大,气泡的形状趋于扁平,而表面活性剂的存在阻碍了气泡发生变形,使气泡的波形因子变化幅度降低,气泡保持在近乎球体状态。
In the sewage treatment plants,lakes,reservoirs,estuaries and aquaculture ponds where the dissolved oxygen level needs to be elevated by artificial aeration,it is very important to maintain the dynamic equilibrium of dissolved oxygen through the aerator.There are always surfactants in the domestic sewage and urban wastewater.When these waste waters flow into the above aerated water body,they would affect the oxygenation performance and mass transfer effect of aeration system.In order to investigate the effect of surfactants on the oxygenation performance of microporous aeration system,a series of microporous aeration tests were carried out in a glass tank of 2.0 m long,0.8 m wide and 0.8 m high,in five different air flow rates and anionic surfactant concentration,according to the Standard Test Method for Oxygen from American Society of Civil Engineers(ASCE).The microporous aeration plate fixed in the center of the tank bottom was taken as aerator and the anionic surfactant,i.e.,sodium dodecyl benzene sulfonate(SDBS),was used introduced.Based on the theory of air bubble mass transfer,the oxygen mass transfer coefficient,Sauter mean diameter and form factor were calculated and analyzed.The results showed that,at 1.0 mg/L SDBS concentration,the oxygen volumetric mass transfer coefficient was increased and the oxygen mass transfer effect was improved in different air flow rates.But at 1.0~5.0 mg/L SDBS concentration,with the increase of the concentration,the oxygen volumetric mass transfer coefficient decreased.The Sauter mean diameter of the bubbles in water containing surfactant was decreased by 22.76% compared to pure water.The variation of the form factor was small,and thus the air bubbles were kept in the almost spherical shape.While,in the tests without surfactants,the form factor of the bubbles had a larger variation and the shape of the air bubbles tended to be flat.
In the sewage treatment plants,lakes,reservoirs,estuaries and aquaculture ponds where the dissolved oxygen level needs to be elevated by artificial aeration,it is very important to maintain the dynamic equilibrium of dissolved oxygen through the aerator.There are always surfactants in the domestic sewage and urban wastewater.When these waste waters flow into the above aerated water body,they would affect the oxygenation performance and mass transfer effect of aeration system.In order to investigate the effect of surfactants on the oxygenation performance of microporous aeration system,a series of microporous aeration tests were carried out in a glass tank of 2.0 m long,0.8 m wide and 0.8 m high,in five different air flow rates and anionic surfactant concentration,according to the Standard Test Method for Oxygen from American Society of Civil Engineers(ASCE).The microporous aeration plate fixed in the center of the tank bottom was taken as aerator and the anionic surfactant,i.e.,sodium dodecyl benzene sulfonate(SDBS),was used introduced.Based on the theory of air bubble mass transfer,the oxygen mass transfer coefficient,Sauter mean diameter and form factor were calculated and analyzed.The results showed that,at 1.0 mg/L SDBS concentration,the oxygen volumetric mass transfer coefficient was increased and the oxygen mass transfer effect was improved in different air flow rates.But at 1.0~5.0 mg/L SDBS concentration,with the increase of the concentration,the oxygen volumetric mass transfer coefficient decreased.The Sauter mean diameter of the bubbles in water containing surfactant was decreased by 22.76% compared to pure water.The variation of the form factor was small,and thus the air bubbles were kept in the almost spherical shape.While,in the tests without surfactants,the form factor of the bubbles had a larger variation and the shape of the air bubbles tended to be flat.
引文
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[22]Liu Yanyan,Li Yanpeng,Zhu Tingting.Study on modulating shape and velocity of meso-scale bubble using surfactants[J].Journal of Xi’an Jiaotong University,2011,45(10):93-97.[刘艳艳,李彦鹏,朱婷婷.表面活性剂对中尺度气泡形状及速度的调控研究[J].西安交通大学学报,2011,45(10):93-97.]
[2]Cui Li,Wang Ya’na.Present research situation and forecast of surfactant wastewater treatment[J].Industrial Water Treatment,2008,28(2):9-11.[崔励,王雅娜.表面活性剂废水处理研究现状与展望[J].工业水处理,2008,28(2):9-11.]
[3]An Dongzi,Zhang Yangang,Li Wei,et al.The influence of anionic surfactants on the treatment effect of wastewater from the sewage treatment plant and the harmless study of its production wastewater[J].Technology of Water Treatment,2015,41(11):22-24.[安东子,张岩岗,李玮,等.阴离子表面活性剂对污水处理厂处理效果的影响极其生产污水的无害化研究[J].水处理技术,2015,41(11):22-24.]
[4]Dai Liang,He Wenzhi,Li Bingjing,et al.Progress of treatment technologies for wastewater from daily chemicals industry[J].Chemical Industry and Engineering Progress,2014,33(S1):273-278.[戴亮,贺文智,李冰璟,等.日用化学品行业废水处理技术的研究进展[J].化工进展,2014,33(增刊1):273-278.]
[5]Liu Peng,Zheng Xiang,Wang Bo,et al.Progress in the research on the effects of water quality in aeration systems on oxygen mass transfer[J].Industrial Water Treatment,2014,34(9):10-14.[刘鹏,郑祥,王博,等.曝气系统中水质条件对氧传质影响的研究进展[J].工业水处理,2014,34(9):10-14.]
[6]Rosso D,Huo D L,Stenstrom M K.Effects of interfacial surfactant contamination on bubble gas transfer[J].Chemical Engineering Science,2006,61(16):5500-5514.
[7]Wagner M,P?pel H J.Surface active agents and their influence on oxygen transfer[J].Water Science and Technology,1996,34(3/4):249-256.
[8]Liu Chun,Zhang Lei,Yang Jingliang,et al.Effects of surfactants on oxygen transfer in microbubble aeration[C]//Proceedings of the 2009 International Conference on Energy and Environment Technology,Washington D C:IEEE Computer Society,2009,2:531-534.
[9]Wei Yanling,Qi Lu,Liu Guohua,et al.Effect factors affecting oxygen transfer performance of fine bubble diffusers[J].Technology of Water Treatment,2014,40(2):1-7.[魏延苓,齐鲁,刘国华,等.微孔曝气器充氧性能的影响因素[J].水处理技术,2014,40(2):1-7.]
[10]Yin Xunfei,Yang Shuo,Xue Xiaofei,et al.Influence of different fine-pore diffusers and surfactant on oxygenation performance in aeration system[J].Environmental Pollution and Control,2015,37(10):17-20.[尹训飞,杨硕,薛晓飞,等.膜孔参数及表面活性剂对微孔曝气器充氧性能的影响研究[J].环境污染与防治,2015,37(10):17-20.]
[11]Luo Tao,Wang Hongchen,Qi Lu,et al.Pilot scale research on the impact of TDS and surfactant on oxygen mass transfer in fine bubble aeration[J].Acta Scientiae Circumstantiae,2012,32(9):2066-2070.[罗涛,王洪臣,齐鲁,等.总溶解性固体及表面活性剂对微孔曝气传质过程影响的中式研究[J].环境科学学报,2012,32(9):2066-2070.]
[12]Chen Xulu,Wang Hongchen,Qi Lu,et al.Effects of anionic surfactant on oxygen mass transfer in the fine bubble aeration[J].Acta Science Circumstantiae,2013,33(2):395-400.[陈旭露,王洪臣,齐鲁,等.阴离子表面活性剂对微孔曝气氧传质过程影响的研究[J].环境科学学报,2013,33(2):395-400.]
[13]Krzan M,Zawala J,Malysa K.Development of steady state adsorption distribution over interface of a bubble rising in solutions of n-alkanols and n-alkyltrimethylammonium bromides[J].Colloids and Surfaces A:Physicochemical Engineering Aspects,2007,298(l/2):42-51.
[14]Liu Chun,Zhang Lei,Yang Jingliang,et al.Characteristics of oxygen transfer in microbubble aeration[J].Chinese Journal of Environmental Engineering,2010,4(3):585-589.[刘春,张磊,杨景亮,等.微气泡曝气中的氧传质特性研究[J].环境工程学报,2010,4(3):585-589.]
[15]Cheng Xiangju,Zeng Yingxue,Xie Jun,et al.Impact of microporous aeration flow and aeration tube length on oxygen transfer performance in water[J].Transactions of the Chinese Society of Agricultural Engineering,2014,30(22):209-217.[程香菊,曾映雪,谢俊,等.微孔曝气流量与曝气管长度对水体增氧性能的影响[J].农业工程学报,2014,30(22):209-217.]
[16]ASCE.ASCE Standard measurement of oxygen transfer in clean water[M].Virginia:American Society of Civil Engineers,2007.
[17]Gillot S,Capela S,Heduit A.Effect of horizontal flow on oxygen transfer in clean water and in clean water with surfactants[J].Water Research,2000,34(2):678-683.
[18]Akita K,Yoshida F.Bubble Size,interfacial area and liquidphase mean transfer coefficient in bubble columns[J].Industrial and Engineering Chemistry Process Design and Development,1974,13(1):84-91.
[19]Bhavaraju S M,Russell T W F,Blanch H W.The design of gas sparged devices for viscous liquid systems[J].Aiche Journal,1978,24(3):454-466.
[20]Chern J M,Chou S R,Shang C S.Effects of impurities on oxygen transfer rates in diffused aeration systems[J].Water Research,2001,35(13):3041-3048.
[21]Li Er.Theory of optimal bubble group for fine bubble aeration and its application to reaeration Engineering[D].Wuhan:Huazhong University of Science and Technology,2007.[李尔.微孔曝气最优气泡群理论及其在复氧工程中的应用[D].武汉:华中科技大学,2007.]
[22]Liu Yanyan,Li Yanpeng,Zhu Tingting.Study on modulating shape and velocity of meso-scale bubble using surfactants[J].Journal of Xi’an Jiaotong University,2011,45(10):93-97.[刘艳艳,李彦鹏,朱婷婷.表面活性剂对中尺度气泡形状及速度的调控研究[J].西安交通大学学报,2011,45(10):93-97.]