Physical and Hydrodynamic Properties of Spherical Cellulose-Titanium Dioxide Composite Matrix for Expanded Bed Adsorption

Expanded bed adsorption (EBA) has been widely used in industrial downstream bioprocessing. Solid matrix is the principal pillar supporting the successful application of EBA. A novel spherical cellulose-titanium dioxide composite matrix was prepared through the method of water-in-oil suspension thermal regeneration. Its typical physical properties were wet density 1.18g.cm-3, diameters in the range of 100-300um, porosity 85.5%, and water content 72.3%. Expansion characteristics and liquid mixing performance of the matrix in expanded bed were investigated using water and 10% (by mass) glycerol solution as mobile phases. The results indicate that the custom-assembled matrix has a stable flow hydrodynamics and exhibits the same degree of liquid-phase mixing or column efficiency as the commercially available Streamline adsorbent.

Stability of expanded granular sludge bed process for terylene artificial silk printing and dyeing wastewater treatment

Terylene artificial silk printing and dyeing wastewater(TPD wastewater), containing averaged 710 mg/L terephthalic acid(TA) as the main carbon source and the character pollutant, was subjected to expanded granular sludge bed(EGSB) process. The stability of the EGSB process was firstly conducted by laboratory experiment. TA ionization was the predominated factor influencing the acid-base balance of the system. High concentration of TA in wastewater resulted in sufficient buffering capacity to neutralize the volatile fatty acids(VFA) generated from substrate degradation and provided strong base for anaerobic system to resist the pH decrease below 6.5. VFA and UFA caused almost no inhibition on the anaerobic process and biogas production except that pH was below 6.35 and VFA was at its maximum value. Along with the granulating of the activated sludge, the efficiency of organic removal and production rate of biogas increased gradually and became more stable. After start-up, the efficiency of COD removal increased to 57%—64%, pH stabilized in a range of 7.99—8.04, and production rate of biogas was relatively high and stable. Sludge granulating, suitable influent of pH and loading were responsible for the EGSB stability. The variation of VFA concentration only resulted in neglectable rebound of pH, and the inhibition from VFA could be ignored in EGSB. The EGSB reactor was stable for TPD wastewater treatment.

Adsorbents for Expanded Bed Adsorption： Preparation and Functionalization

Expanded bed adsorption(EBA),a promising and practical separation technique,has been widely studied in the past two decades.The development of adsorbents for EBA process is a challenging course,with the special design and preparation according to the target molecules and specific expanded bed systems.Many types of supporting matrices for expanded bed adsorbents have been developed,and their preparation methods are being consummated gradually.These matrices are activated and then coupled with ligands to form functionalized adsorbents,including ion-exchange adsorbents,affinity adsorbents,mixed mode adsorbents,hydrophobic charge induction chromatography adsorbents and others.In this review,the preparation of the matrices for EBA process is summa-rized,and the coupling of ligands to the matrices to prepare functionalized adsorbents is discussed as well.

Dense Pellicular Agarose-Glass Beads for Expanded Bed Application: Flow Hydrodynamics and Solid Phase Classifications

Two dense pellicular agarose-glass matrices of different sizes and densities, i.e., AG-S and AG-L, have been characterized for their bed expansion behavior, flow hydrodynamics and particle classifications in an expanded bed system. A 26 mm ID column with side ports was used for sampling the liquid-solid suspension during expanded bed operations. Measurements of the collected solid phase at different column positions yielded the particle size and density distribution data. It was found that the composite matrices showed particle size as well as density classifications along the column axis, i.e., both the size and density of each matrix decreased with increasing the axial bed height. Their axial classifications were expressed by a correlation related to both the particle size and density as a function of the dimensionless axial bed height. The correlation was found to fairly describe the solid phase classifications in the expanded bed system. Moreover, it can also be applied to other two commercial solid matrices designed for expanded bed applications.

SOLID MATRICES FOR EXPANDED BED ADSORPTION OF PROTEINS

Expanded bed adsorption (EBA) has been introduced as a primary recovery step for protein purification from a whole fermentation broth or unclarified cell homogenates. It can also be integrated with a fermentation or cell disruption process. Solid matrix is the principal pillar supporting the successful application of the EBA technology. This article summarizes the solid matrices employed in and developed for the EBA process to date. Further development of solid matrices for the expanded bed technique in the recovery of various biological substances from different sources has been addressed.

Effects of internals on phase holdup and backmixing in a slightly-expanded-bed reactor with gas–liquid concurrent upflow

Five different internals were designed,and their effects on phase holdup and backmixing were investigated in a gas–liquid concurrent upflow reactor where the spherical alumina packing particles of three diameters(3.0,4.5 and6.0 mm)were slightly expanded under the conditions of varied superficial gas velocities(6.77×10-2-3.61×10-1 m·s-1)and superficial liquid velocities(9.47×10-4-2.17×10-3 m·s-1).The experimental results show that the gas holdup increases with the superficial gas velocity and particle size,opposite to the variational trend of liquid holdup.When an internal component is installed amid the upflow reactor,a higher gas holdup,a less liquid holdup and a larger Peclet number characterizing the weaker backmixing are obtained compared to those in the bed without internals under the same operating conditions.Additionally,the minimal backmixing is observed in the reactor equipped with the internals with a novel multi-step design.Finally,empirical correlations were proposed for estimating gas holdup,liquid holdup and Peclet number with the relative deviations within 11%,12%and 25%,respectively.

Adsorption of Protein in the Expanded Bed

The influence of operation parameters on the adsorption performance of protein (bovin serum albumin, BSA) in an expanded bed was studied using Streamline diethyl aminoethyl (DEAE). The result of residence time distributions (RTD) and breakthrough curves showed that adsorption performance of the expanded bed could not be improved by increasing the flow velocity at the range from 16ml·min-1 to 26ml·min-1. The increase of protein concentration from 0.5 mg·ml to 2 mg·ml-1 resulted in poor adsorption performance. With increasing temperature from 5℃ to 30℃ and the sedimented bed height from 11.5cm to 22.5cm, the adsorption characteristics in the expanded bed were improved.

Expanded Bed Recovery of D-2-Chloropropionic Acid Dehalogenase Using TiOe-Densified Cellulose Anion Exchanger

The TiO2-densified cellulose composite beads were activated by epichlorohydrin and coupled with diethylamine, to function as an anion exchanger for expanded bed chromatography. The adsorbent exhibited a favorable performance of expanded bed adsorption for proteins, and therefore was applied to the expanded bed recovery of D-2-chloropropionic acid dehalogenase directly from the unclarified homogenate of Pseudomonas sp. NT21. The binding capacity of the dehalogenase was found to be 8.54U·ml^-1 adsorbent, and two active peaks were eluted respectively at 0.15mol·L^-1 and 0.3mol·L^-1 （NH4）2SO4. The result indicated that the overall enzyme yield was 68%, with a purification factor of 22. In comparison to other recovery processes, the yield of the expanded bed process rises at least 70%, simultaneously saving a great deal of operation time and costs.

Single-step Purification of Molecular Chaperone GroEL by Expanded Bed Chromatography

Expanded bed adsorption (EBA) is an integrative downstream processing technique for the purification of biological substances directly from unclarified feedstock. In this study, molecular chaperone GroEL, an important protein folding helper both in vivo and in vitro, was purified by the single-step EBA technique from the unclarified homogenate of recombinant E. coli cells. Compared with packed bed adsorption, the EBA technique provided a single-step approach to yield an electrophoretic purity of GroEL. After the homogenate loading and column washing in the expanded bed mode, the GroEL protein was recovered by stepwise salt-gradient elution in packed-bed or expanded-bed modes, respectively. The expanded-bed elution mode was found as efficient as the packed-bed mode in the purification of GroEL from cell disruptate.

Hydraulic modeling of an anaerobic expanded bed reactor for municipal sewage treatment

Anaerobic expanded bed reactor(AEBR) is mostly used for the treatment of fairly low strength wastewaters. Since the performance of AEBR largely depends on its hydraulic characteristics, residence time distribution(RTD) method is commonly used for investigation of the hydraulic characteristics of AEBR under different ascending velocity of mixed liquor. In this paper, a pilot-scale AEBR reactor is investigated for treatment of municipal sewage in which lithium chloride is used as a tracer. The results show that the AEBR could be considered as the superimposition of several constant stirred tank reactors(CSTR) and the increase of hydraulic up-flow velocity could increase the number of the CSTR and decrease the volume rate of the dead zone. The optimal up-flow velocity of the investigated AEBR was approximately 1.9 m/h in the municipal sewage treatment.

The Effect of Non-acidified Wastewater on Expanded Granular Sludge Bed （EGSB） Reactors Performance

The textile processing plants utilize a wide variety of dyes and other chemicals such as acids, bases, salts, detergents, sizes, oxidants, mercerizing and finishing chemicals. Many of these are not retained in the final product and are discharged in the effluent. Therefore, the objective of this study was to assess the performance of EGSB （Expanded Granular Sludge Bed） reactor to treat non-acidifie wastewater. Several experiments using starch and volatile fatty acids as model substrates were conducted. The problems of piston formation were evaluated at a variety of relevant operational conditions, such as substrate concentration, organic and hydraulic loading rates. The results showed that newly grown acidogenic biomass diluted original methanogenic biomass and the granular sludge in the EGSB reactor deteriorated. The piston formation in the EGSB reactor that was fed with non-acidified wastewater occurred due to high growth of acidogenic biomass and high upflow velocity applied in the system.

废水处理硝酸盐异化还原与厌氧氨氧化/反硝化耦合工艺构建

采用厌氧膨胀颗粒污泥床反应器(EGSB)处理含COD、氨氮和硝氮的模拟废水,旨在高浓度有机废水处理系统中快速构建厌氧氨氧化(Anammox)运行工艺。通过接种少量Anammox污泥和逐步提高氨氮浓度的操作方式,在连续运行58d后,系统成功启动Anammox反应,此时的总氮和COD去除率稳定在97%和98%以上。物料衡算显示,Anammox反应途径对氮的去除贡献逐渐增加,硝酸盐异化还原(DNRA)耦合Anammox和反硝化共同促进了系统的同步脱氮除碳。对微生物群落分析发现,Candidatus Kuenenia相对丰度由0.27%快速升高至35.87%,DNRA菌(Ignavibacterium、Thermogutta)及反硝化菌(Azospira、Gp3)在体系内共存。通过基因注释法,检测出了Anammox、DNRA、硝酸盐还原及亚硝酸盐还原关键基因。运行过程中,颗粒污泥颜色变红且粒径增大;胞外聚合物(EPS)分析表明多糖(PS)和蛋白质(PN)含量增加而PN/PS下降;三维荧光光谱发现腐殖酸类物质增多。研究结果为高浓度有机含氮废水高效处理提供了一种新的工艺途径。

非均相芬顿+强化EGSB处理制药废水研究

针对目前制药废水COD质量浓度高,组成成分复杂、可生化性差等导致其成为制药行业亟待解决的问题,采用瑞盛环境股份有限公司专利技术—非均相芬顿-厌氧膨胀颗粒污泥床制药废水处理装置(ZL202221588605.3),探讨了非均相芬顿+强化EGSB的处理效能.研究表明,该工艺处理制药废水性能良好,非均相芬顿可在酸性和偏碱性(pH2~9)的条件下实现较强的氧化性能,在避免处理系统酸碱度调节的同时,H2O2的投加量也降至80 mmol/L,经后续强化EGSB工艺处理的制药废水,出水各项指标符合园区污水处理厂接管标准.

膨胀床离子交换吸附分离纳豆激酶

对膨胀床分离纳豆激酶过程的各个阶段进行了考察。在填充床上的探索性实验表明,吸附时最佳的pH为6.0,电导率应低于6.2mS/cm。在膨胀床上样吸附阶段,考察了保持流速不变和保持床层膨胀率不变2种操作方式,结果表明采用控制膨胀率不变的方法更适合纳豆激酶这种料液的粘度和平衡缓冲液的粘度相差不大的情况;在冲洗阶段,通过考察颗粒冲洗的效率确定采用平衡缓冲液冲洗;洗脱阶段采用填充床模式洗脱。与传统方法相比,用膨胀床对纳豆激酶进行分离和纯化,操作步骤从6步减少为2步,操作时间缩短了8—10h,回收率提高了约50%。

膨胀床的膨胀特征和流体混合性能

对膨胀床的膨胀特性和流体混合性能进行了研究。考察了流体粘度，考察一流体粘度、温度、流速和沉降床层高度等因素的影响。结果表明，Ｓｔｒｅａｍｌｉｎｅ ＤＥＡＥ在Ｓｔｒｅａｍｌｉｎｅ２５中的膨胀行为可以用Ｒｉｃｈａｒｄｓｏｎ－Ｚａｋｉ方程来描术。在所研究的范围内，流体粘度，流速客床层高度的增大都会引起轴向混合系数的增大；膨胀床的轴向混合系数很小（〈４×１０＾６ｍ＾２．ｓ＾－１）表明人流动似平推流动。

膨胀床吸附高效纯化牛血红蛋白

探索了将膨胀床吸附层析应用于动物血液蛋白质的提取 ,尝试了直接从牛血红细胞破碎液中纯化血红蛋白 .对该过程采用的吸附介质及 pH值、离子强度、温度、洗脱条件等因素对高铁血红蛋白生成、产品纯度以及回收率等的影响进行探索 .选择了最佳吸附介质StreamlineSP ,确定了优化的吸附条件为 :吸附过程选用离子强度为 10mmol·L-1的磷酸盐缓冲系统 ,进料线流速 3 3cm·min-1,进料 pH值 6 6 ,改变缓冲液pH值为 7 2进行洗脱 ,操作温度 4℃ .该技术省去了离心去除碎片步骤 ,有效地控制了纯化过程中无载氧能力的高铁血红蛋白的生成 ,动态吸附容量达到 70～ 75mg·ml-1,只经一步操作产品纯度达电泳纯 ,高铁血红蛋白含量仅为5 4 % .与现有的膜过滤 -层析纯化方法相比 ,膨胀床吸附法操作时间短 ,提取收率高 ,产品活性损失小 ,是一种简捷、高效。

扩张床吸附基质研究进展

针对扩张床吸附这一新型蛋白质分离纯化技术 ,论述了吸附剂基质对该项技术应用的重要性 ,并且评述了近十年来扩张床吸附基质的研究状况 ,在此基础上重点介绍了基质所需的特性。

膨胀床吸附层析及其在生化分离中的应用

膨胀床是稳定无返混的流化床，它可直接从料液中吸附目标产物，不需预先除去料液中的颗粒。膨胀床将料液的澄清、浓缩和初步纯化集成于一个单元操作中，大大降低了分离过程的复杂程度，提高分离效率。吸附剂的物性、膨胀床装置、料液的性质以及操作条件等因素对膨胀床的稳定和分离效率有很大的影响。

微膨胀床渣油加氢处理反应器的研究

为考察微膨胀床渣油加氢处理反应器的气液流动状态、床层膨胀率及反应性能,常温、常压下用模拟油气在冷模实验装置上进行了近似模拟,并采用微膨胀床/固定床中型实验装置处理了中东高硫渣油。结果表明:按返混程度微膨胀床反应器可分为3个区域;大粒径、低堆密度催化剂易膨胀;空塔气速对床层膨胀率影响大于空塔液速;中型实验装置可脱除渣油中80%以上硫和钒以及50%以上镍和残炭,其中微膨胀床脱除率占50%以上。

渣油加氢微膨胀床反应器中的气液流动状态及床层膨胀率

在常温常压下用模拟渣油和模拟氢气近似模拟了微膨胀床渣油加氢处理反应器内的气液流动状态,考察了催化剂粒径和堆密度、虚拟气液流速以及催化剂装填高度对催化剂床层膨胀率的影响。实验结果表明:大粒径、低堆密度的催化剂床层膨胀率较高;虚拟气速与床层膨胀率关系曲线上存在拐点,拐点值随催化剂装填高度增加而增大;虚拟液体流速对催化剂床层膨胀率影响较小;在工业操作条件下,微膨胀床渣油加氢处理反应器的催化剂床层膨胀率小于10%;催化剂装填高度对床层膨胀率有明显的影响,催化剂装填量较大时,需要采用较高的气油比才能保证催化剂床层处于微膨胀状态。