Comparison of mass transfer efficiency in horizontal rotating packed beds and rotating biological contactors

In this study, the mass transfer efficiencies of a novel horizontal rotating packed (h‐RPB) bed and the conventional disc‐type rotating biological contactor (RBC) were studied at four speeds and seven submergences. Pall rings of two different sizes (25, 38 mm), superintalox saddles and a wiremesh spiral bundle were used as packings in the h‐RPB. Volumetric gas–liquid mass transfer coefficients were determined by unsteady state absorption of atmospheric oxygen in de‐aerated water. Power consumption per unit liquid volume has been found for all geometries tested. The oxygen transfer efficiency values for the h‐RPB were found to be 2–5 kg kWh^?1 and for the disc RBC were found to be 1–2 kg kWh^?1. The performance of the h‐RPB was also compared with other gas–liquid contactors such as surface aerators. The study proves that the h‐RPB is a energy efficient alternative to conventional contactors. Copyright © 2005 Society of Chemical Industry     

生物转盘处理城镇污水的试验研究

针对城镇污水排放量大、污水成分日趋复杂的特点,采用生物转盘工艺处理城镇污水,主要考察生物转盘对有机物降解和脱氮的试验研究。结果表明:经生物转盘处理后,污水中的CODCr、氮得到很好的去除。当HRT控制为6 h,转速为2 r/min时,CODCr去除率达到90%以上。在m(CODCr)∶m(NH3-N)=1.5时,TN去除率达50%,去除效果不理想,而当m(CODCr)∶m(NH3-N)=3.3以上时,TN去除率达87%左右,脱氮效果较好。     

活性炭生物转盘的制备及处理有机模拟废水

为了寻找一种质轻高效的新型生物转盘盘片材料,实验以活性炭作为生物膜附着的载体,聚丙烯塑料板为基体,采用化学氧化-铁离子覆盖技术制备了活性炭生物转盘盘片。使用该活性炭生物转盘处理有机模拟废水,以COD和NH3—N质量浓度变化为评价指标,借助微生物显微镜观察了挂膜期间微生物的生长过程。结果表明,该盘片具有独特的微生物吸附能力,微生物量达到2.60×109个/g,生物膜干质量为16.909 6 g/m2;在进水初始COD质量浓度为1 000 mg/L、NH3—N质量浓度为100 mg/L左右时,当HRT为12 h时,盘片的有机去除负荷为5.61 g/m2;当循环进水3 d时,COD和NH3—N去除率均在80%以上,该三级生物转盘反应器各级污染物去除率均较高,第1级去除效果最显著,处理后水质达到了国家污水综合排放标准(GB8978-96)的二级标准。     

生物转鼓反应器氧转移特性及运行效能

采用一种研制的新型生物转鼓反应器(RDBC),内部装填MBBR悬浮填料,通过调节浸没深度和转速可实现厌氧、缺氧、好氧等工况条件下运行,其氧总体积传质系数K_La可达25.87 h^-1,动力效率可达228.62g·(kW·h)^-1。利用生物转鼓分段进水后置反硝化工艺处理模拟生活污水,结果表明:在进水流量6 L·h^-1(HRT 18 h),好氧生物转鼓反应器浸没高度比2/3、转速8 r·min^-1、DO 3.0 mg·L^-1,缺氧生物转鼓反应器浸没高度比5/6、转速4 r·min^-1、DO 1.0 mg·L^-1,进水流量分配比3:1,进水COD、NH₄⁺-N和TN浓度平均值分别为385.0、38.0和38.0 mg·L^-1时,COD、NH₄⁺-N和TN去除率分别达到90.4%、93.7%和80.9%,出水水质可满足我国《城镇污水处理厂污染物排放标准》(GB 18918-2002)一级A排放标准要求。     

改性活性炭纤维对生物转盘挂膜的影响

实验采用新型炭材料活性炭纤维作为生物膜附着的载体,考察了改性前后活性炭纤维对生物转盘挂膜以及对油田污水处理效果的影响。结果表明,经浓H2SO4-KMnO4处理后的活性碳纤维平衡含水质量分数为27.79%,表面酸性官能团质量摩尔浓度达到1.723 mol/g。表面改性处理的活性炭纤维较未经预处理的挂膜对比发现,改性处理的活性炭纤维载体的生物转盘微生物数量达到5.67×109个/g,生物膜干质量达到23.025 8 g/m2,COD去除率最高达95.81%,明显高于未经处理的活性炭纤维转盘。     

Hydrodynamics and mass transfer performance of rotating sieved disc contactors used for reversed micellar extraction of protein

The extraction of protein by continuous liquid-liquid extraction was investigated in a rotating disc contactor (RDC) and a rotating sieved disc contactor (RSDC) with and without stators. Hydrodynamics and mass transfer performance for reversed micellar extraction of lysozyme in RDC/RSDC I and RSDC II have been investigated. The dispersed phase holdup has increased with the increase of rotor speed. Pratt's equation was used for calculating the characteristic velocity. An inverse relation was observed between the characteristic velocity and rotor speed. The estimated overall mass transfer coefficient was increased by increasing the rotor speed. For an extraction column, the overall hydrodynamics and mass transfer performance can be judged by a volumetric utilization factor. At high rotor speeds, volumetric utilization factor for RSDCs is higher than that of RDC. The RSDC II has been successfully applied in reversed micellar extraction of protein.     

The interaction of solute transfer,contaminants and drop break-up in rotating disc contactors: Part I. Correlation of drop breakage probabilities

The breakage process of single drops in RDC liquid-liquid extraction columns has been investigated. The breakage probability and daughter drop size distribution were the measured characteristics. Binary systems, non-equilibrated ternary systems with mass transfer in both directions (c → d and d → c) and systems with surface active agent added were used in the experiments. A model of the breakage probability was developed based on a modified Weber number, taking into account the applied shearing stress and the resisting interfacial tension force. It is shown that breakage probability can be estimated if interfacial tension is known as a function of interfacial conditions.     

转盘反应器固定根霉重复批次发酵生产脂肪酶

以聚氨酯海绵为载体将根霉固定于转盘表面,利用转盘反应器实现脂肪酶的固定化发酵。考察了通气量、转速、装液量及转盘个数等操作参数对发酵过程的影响,得到了优化的反应操作条件,即通气量4 L·min^-1,转速100 r·min^-1,装液量3.5L,采用三个转盘。在上述条件下进行重复批次实验,可重复5批次, 单位时间产率10931.1 U·h^-1, 是批次反应的3.5倍。固定化细胞连续发酵,大大缩短了发酵的时间, 酶的平均活力和时间产率获得大幅提高。     

旋转接触氧化工艺处理度假区污水回用的设计及运行

采用旋转接触氧化工艺处理某度假区污水,用于度假区内景观水体用水,自假区开园投产以来系统运行性能良好,出水水质优良,对景观水体无不良影响。系统运行能耗低,占地面积小,启动迅捷简便,管理简单,运行费用低,表明旋转接触氧化工艺是处理以排放生活污水为主的小区污水的良好技术。     

生物转盘同步去除化学需氧量和氮的实验研究

采用单轴三级生物转盘（RBC）,进行了生物转盘同步去除化学需氧量和氮的试验研究。水温度15 ℃,进水COD浓度为400mg/L左右时,转盘对化学需氧量的去除率达到85%左右。控制适宜的碱度,转盘系统氨氮的硝化率在75%左右、总氮（TN）的去除率在50%左右。增设硝化液回流系统后,总氮的去除率显著提高,特别是回流比为200%时,TN去除率在低温下可达73.87%。实验表明生物转盘对化学需氧量和氮有较好的同步去除效果。     

The Interaction of solute transfer,contaminants and dro break-up in rotating disc contactors: Part II. The coupling of the mass transfer and breakage processes via interfacial tension

In order to investigate the influence of solute transfer and of surface active agents on the drop breakage process in liquih liquid extraction columns, their effect on the interfacial tension has to be studied in detail. The difficulty encountered is that the interfacial tension during solute transfer continuously changes and that no simple apparatus is commercially available which can measure these varying interfacial tension values. An attempt has been made here to theoretically predict them. The equations developed to predict the interfacial tension variation can be combined with a model for the breakage process and hence drop size distributions can be calculated from stage to stage. Applying a new combined film mass transfer coefficient model which takes into account the effect of contaminants, single drop extraction performance has been calculated for simplified conditions of constant bulk concentration in the continuous phase. Calculated efficiencies have been compared with experimental data and a good simulation of contaminant effects and dependency on drop size has been found. The calculations were restricted to low dispersed phase hold-up values, so that coalescence effects could be ignored. This work provides the required support for a procedure to be applied to counter-current flow extraction columns.     

A correlation for dispersed phase axial mixing coefficients in rotating disc contactors

A correlation for the estimation of dispersed phase axial mixing coefficients in terms of all the operating and fundamental variables was established. The proposed correlations are found to be a good representation of the present data (260 data points) obtained using four liquid‐liquid systems from two different sources. Copyright © 2005 Society of Chemical Industry     

射流生物转盘反应器特性的试验研究

研制了一种射流驱动(含曝气)生物转盘反应器,以生活污水作为处理对象,探讨了停留时间、气水比对净化效果的影响。该装置通过射流喷射器实现曝气、自吸污水以及推动转盘,简化了装置,其强制充氧方式提高了氧传递效率,对生活污水CODCr去除率可以达到80%以上。     

两级曝气生物滤池处理生活污水的中试研究

通过两级曝气生物滤池处理城市生活污水的中试研究,探讨气水比、水力负荷、回流比及甲醇投加量等工程控制参数,对两级曝气生物滤池处理城市生活污水效果的影响。结果表明,当气水体积比为3,水力负荷为2～3m3/(m2·h),回流比为80%,甲醇投加量为80mg/L,滤料高度均为2.5m时,两级曝气生物滤池处理效果最佳,其出水可达《城镇污水处理厂污染物排放标准》标准中的一级A标准。     

曝气生物滤池处理含氰废水的启动性能及污染物去除特性

为了探讨曝气生物滤池（BAF）对氰化物的去除能力,采用两级曝气生物滤池对含氰废水进行了启动研究。结果表明,当BAF1和BAF2的HRT分别为7 h和5 h、进水温度为20～25 ℃、气水比为10∶1、进水COD为400 mg/L左右（葡萄糖配水）时,随着进水CN?的增加,两级BAF对CN?、COD和TN的去除率逐渐下降。当进水CN?从20.22 mg/L增加到65.23 mg/L时,两级BAF对CN?、COD和TN的去除率相应从92.1%、90.2%和61.7%降至59.1%、53%和25.4%。当初始CN?低于35.34 mg/L时,经过24 h闷曝后,BAF对CN?的去除率可达99%以上,出水CN?低于0.2 mg/L。初始CN?越高,BAF对CN?的降解速率越慢,完全降解CN?所需的时间 越长。     

生物接触氧化技术在生活小区污水处理中的应用

利用悬挂式软性纤维填料制备了生物接触氧化塔,并对生活小区污水进行处理,三个月的试验结果,表明:在HRT=3h的条件下,当原水COD在300～400mg/L,氨氮在30～80mg/L范围时,出水氨氮<1mg/L、COD<50mg/L、SS<15mg/L,此时,系统硝化负荷最高达0.50kg/(m3·d)有机负荷最高达3.2kg/(m3·d)。由实验结果得出,HRT为1.5h,在有机负荷2kg/(m3·d)时,水力负荷是影响硝化的关键因素。     

A new correlation for characteristic velocity in rotating disc contactors

On the basis of present experimental results along with those of available literature (1539 experimental results for 12 systems from 13 different sources) with a wide range of variables, a general correlation for the prediction of characteristic velocity, involving phase flow rates, rotor speed (in terms of Froude number), column geometry and also the physical properties, is presented. The present proposed correlations are more accurate than those previously reported.     

加压溶氧废水生物处理技术研究进展

论述了国内外加压生物处理技术的研究进展,系统介绍了基于该技术的各类新工艺,并对其处理效果进行了比较分析,对今后的发展趋势作了展望.研究表明,加压溶氧技术是废水生物处理新技术的一个重要发展方向,该技术适用于高浓度难降解有机废水的处理.     

生物处理技术在高浓度有机废水处理中的研究进展

阐述了高浓度有机废水的特点及危害,系统地介绍了国内外目前高浓度有机废水的主要生物处理技术及其研究现状,并提出今后高浓度有机废水治理的重点是优化组合技术及新技术的研究开发.