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.

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.

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.

High rate production of concentrated sulfides from metal bearing wastewater in an expanded bed hydrogenotrophic sulfate reducing bioreactor

Metallurgical wastewaters contain high concentrations of sulfate,up to 15 g L^(-1).Sulfate-reducing bioreactors are employed to treat these wastewaters,reducing sulfates to sulfides which subsequently coprecipitate metals.Sulfate loading and reduction rates are typically restricted by the total H2S concentration.Sulfide stripping,sulfide precipitation and dilution are the main strategies employed to minimize inhibition by H2S,but can be adversely compromised by suboptimal sulfate reduction,clogging and additional energy costs.Here,metallurgical wastewater was treated for over 250 days using two hydrogenotrophic granular activated carbon expanded bed bioreactors without additional removal of sulfides.H2S toxicity was minimized by operating at pH 8±0.15,resulting in an average sulfate removal of 7.08±0.08 g L^(-1),sulfide concentrations of 2.1±0.2 g L^(-1) and peaks up to 2.3±0.2 g L^(-1).A sulfate reduction rate of 20.6±0.9 g L^(-1)d^(-1) was achieved,with maxima up to 27.2 g L^(-1)d^(-1),which is among the highest reported considering a literature review of 39 studies.The rates reported here are 6e8 times higher than those reported for other reactors without active sulfide removal and the only reported for expanded bed sulfate-reducing bioreactors using H2.By increasing the influent sulfate concentration and maintaining high sulfide concentrations,sulfate reducers were promoted while fermenters and methanogens were suppressed.Industrial wastewater containing 4.4 g L^(-1) sulfate,0.036 g L^(-1) nitrate and various metals(As,Fe,Tl,Zn,Ni,Sb,Co and Cd)was successfully treated with all metal(loid)s,nitrates and sulfates removed below discharge limits.

New measurements on hydrodynamics in a gas-liquid-solid expanded bed

The solid holdup,in a 150 mm-ID×2460 mm-height gas-liquid-solid expanded bed with air,water and glass beads(the diameter of particles is 0.6-0.8 mm)was firstly investigated based on the immersion-type online multiphase measuring instrument,and bubble behavior was studied via the BVW-2 double electrical conductivity probe.The effect of the superficial gas velocity and liquid velocity on the expanded ratio,the transition ratio,the bubble rising velocity,the gas holdup and the solid holdup was studied.It is discovered that compared with the gas velocity,the liquid velocity has stronger impact on the expanded ratio,but it is opposite for the transition ratio.The average gas holdup and solid holdup increase linearly as the superficial gas velocity goes up.Among it,the gas holdup increases greater in the center,while the solid holdup increases greater near the wall.Compared with it,when the superficial liquid velocity rises,the average gas holdup hardly changes,but the average solid holdup keeps decreasing,especially the solid holdup distributes flatter with the increase of the superficial liquid velocity.

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.

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.

Startup and operation of anaerobic EGSB reactor treating palm oil mill effluent

A bench-scale expanded granular sludge bed （EGSB） reactor was applied to the treatment of palm oil mill effluent （POME）. The reactor had been operated continuously at 35℃ for 514 d, with organic loading rate （OLR） increased from 1.45 to 17.5 kg COD/（m^3·d）. The results showed that the EGSB reactor had good performance in terms of COD removal on the one hand, high COD removal of 91% was obtained at two days＇ of hydraulic retention time （HRT）, and the highest OLR of 17.5 kg COD/（m^3·d）. On the other hand, only 46% COD in raw POME was transformed into biogas in which the methane content was about 70% （V/V）. A 30-d intermittent experiment indicated that the maximum transformation potential of organic matter in raw POME into methane was 56%. Volatile fatty acid （VFA） accumulation was observed in the later operation stage, and this was settled by supplementing trace metal elements. On the whole, the system exhibited good stability in terms of acidity and alkalinity. Finally, the operational problems inherent in the laboratory scale experiment and the corresponding countermeasures were also discussed.

Integration of biological method and membrane technology in treating palm oil mill effluent

Palm oil industry is the most important agro-industry in Malaysia, but its by-product-palm oil mill effluent （POME）, posed a great threat to water environment. In the past decades, several treatment and disposal methods have been proposed and investigated to solve this problem. A two-stage pilot-scale plant was designed and constructed for POME treatment. Anaerobic digestion and aerobic biodegradation constituted the first biological stage, while ultrafiltration （UF） and reverse osmosis （RO） membrane units were combined as the second membrane separation stage. In the anaerobic expanded granular sludge bed （EGSB） reactor, about 43% organic matter in POME was converted into biogas, and COD reduction efficiency reached 93% and 22% in EGSB and the following aerobic reactor, respectively. With the treatment in the first biological stage, suspended solids and oil also decreased to a low degree. All these alleviated the membrane fouling and prolonged the membrane life. In the membrane process unit, almost all the suspended solids were captured by UF membranes, while RO membrane excluded most of the dissolved solids or inorganic salts from RO permeate. After the whole treatment processes, organic matter in POME expressed by BOD and COD was removed almost thoroughly. Suspended solids and color were not detectable in RO permeate any more, and mineral elements only existed in trace amount （except for K and Na）. The high-quality effluent was crystal clear and could be used as the boiler feed water.

Performance and microbial diversity of an expanded granular sludge bed reactor for high sulfate and nitrate waste brine treatment

The disposal of waste brines has become a major challenge that hinders the wide application of ion- exchange resins in the water industry in recent decades. In this study, high sulfate removal efficiency （80%-90%） was achieved at the influent sulfate concentration of 3600 mg/L and 3% NaC1 after 145 days in an expanded granular sludge bed （EGSB） reactor. Furthermore, the feasibility of treating synthetic waste brine containing high levels of sulfate and nitrate was investigated in a single EGSB reactor during an operation period of 261 days. The highest nitrate and sulfate loading rate reached 6.38 and 5.78 kg/（m3-day） at SO42--S/NO3-N mass ratio of 4/3, and the corresponding removal efficiency was 99.97% and 82.26% at 3% NaC1, respectively. Meanwhile, 454-pyrosequencing technology was used to analyze the bacterial diversity of the sludge on the 240th day for stable operation of phase X. Results showed that a total of 9194 sequences were obtained, which could be affiliated to 14 phyla, including Proteobacteria, Firmicutes, Chlorobi, Bacteroidetes, Synergistetes and so on. Proteobacteria （77.66%） was the dominant microbial population, followed by Firmicutes （12.23%） and Chlorobi （2.71%）.

Production and application of anaerobic granular sludge produced by landfill

Sludge granulation is considered to be the most critical parameter governing successful operation of an upflow anaerobic sludge blanket and expanded granular sludge bed （EGSB） reactors. Pre-granulated seeding sludge could greatly reduce the required startup time. Two lab-scale and a pilot-scale EGSB reactors were operated to treat Shaoxing Wastewater Treatment Plant （SWWTP） containing wastewater from real engineering printing and dyeing with high pH and sulfate concentration. The microbiological structure and the particle size distribution in aerobic excess sludge, sanitary landfill sludge digested for one year, and the granular sludge of EGSB reactor after 400 d of operation were analyzed through scanning electron microscopy （SEM） and sieves. The lab-scale EGSB reactor seeded with anaerobic sludge after digestion for one year in landfill showed obviously better total chemical oxygen demand （TCOD） removal efficiency than one seeded with aerobic excess sludge after cation polyacrylamide flocculation-concentration and dehydration. The TCOD removed was 470.8 mg/L in pilot scale EGSB reactor at short hydraulic retention time of 15 h. SEM of sludge granules showed that the microbiological structure of the sludge from different sources showed some differences. SEM demonstrated that Methanobacterium sp. was present in the granules of pilot-scale EGSB and the granular sludge produced by landfill contained a mixture of anaerobic/anoxic organisms in abundance. The particle size distribution in EGSB demonstrated that using anaerobic granular sludge produced by sanitary landfill as the seeding granular sludge was feasible.

Development of a novel modified EGSB reactor for municipal sewage treatment at ambient temperatures

A novel modified expanded granular sludge bed(EGSBm) reactor was developed for anaerobic treatment of municipal sewage with mixed liquid recirculation instead of effluent recirculation commonly adopted by a conventional EGSB(EGSBc) reactor.Performances of these two reactors were compared in treating municipal sewage at ambient temperatures ranging from 8 to 26 ℃.At an upflow liquid velocity(Vup) of 10.3 m/h,the mean concentrations of filtrated COD(CODfilt) and COD of the EGSBm effluent were determined to be 59.4 and 95.9 mg/L,respectively,which were significantly lower than those of the EGSBc effluent operated under identical experimental conditions.When the organic loading rate was suddenly increased from 1.2 to 7.2 kg COD/(m3·d),the EGSBm regained the removal efficiency of previous operation phase in 10 d.Hydrodynamic characteristics of the reactors were compared using the residence time distribution(RTD) model.It was found that the treatment efficiency of EGSBm kept increasing as the Vup increased.The polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis(PCR-DGGE) technique was used to analyze the microbial diversity in EGSBm.Fingerprinting pattern indicated that some species in the inoculating sludge were still reserved in the granular sludge of EGSBm,moreover,several new species occurred.

Quick start-up of EGSB reactor treating fresh leachate of municipal solid waste

An expanded granular sludge bed （EGSB） reactor inoculated with anaerobic granular sludge was started up with its COD removal performance, self-balancing of pH, biogas production rate and characteristics of the granular sludge during the start-up period being investigated. The results indicated that the EGSB reactor can be started up successfully in 27 d by increasing the organic loading rate rapidly. The removal efficiency of COD was maintained above 93% with influent COD concentration of 25 000 mg/L and OLR of 37.94 kgCOD/（m 3 ·d）. The EGSB reactor with good pH self-balancing could be fed with fresh leachate of low pH value （4 5）. The biogas production rate was closely related with OLR and COD reduction. Every gram of COD fed （consumed） to the reactor produced 0.34 L STP （0.36 L STP ） biogas with 0.21 L STP （0.23 L STP ） methane. Thus, 65% 70% of the produced biogas was methane. Sixty one percentage of COD fed to the reactor was converted to methane, another 33% was converted to biomass by metabolism, and the other 6% was left in the liquid phase. The specific methanogenic activity （SMA） of the granular sludge had increased by 92% after 27 d dynamic incubation. The granular sludge in the reactor had good settlement performance with majority diameter of 1 2 mm.

Kinetics of municipal sewage degradation in EGSB and UASB reactors at 10 ℃

Kinetics of municipal sewage degradation in Expanded Granular Sludge Bed(EGSB)and Up-flow Anaerobic Sludge Blanket(UASB)reactors at 10℃ were investigated via continuous experimental equipments.The results indicated that the whole reaction process can be simulated by the first-order dynamic equation model.Dynamic parameters such as k,Vmax and Ks of UASB in hydrolysis acidification stage were 1.08 d-1,2.8 d-1 and 372 mg/L comparing to those of 1.18 d-1,3.5 d-1 and 112 mg/L in the methanogenesis stage respectively.The EGSB’s k,Vmax and Ks were 2.91 d-1,14.3 d-1 and 470 mg/L in the hydrolysis acidification stage comparing to those of 1.68 d-1,6.6 d-1 and 103 mg/L in the methanogenesis stage respectively.Comparison of k values of the two stages in UASB and EGSB indicates that hydrolysis acidification stage is the controlling step for the whole reaction process of UASB,while methanogenesis stage is the controlling step in EGSB.Compared with UASB,municipal sewage treatment by EGSB at 10 ℃ can reach the same effluent requirement with lower retention time due to its effluent recirculation.

Optimizing Conditions of Enhancing Granule Sludge Concentration and Performance

An expanded granular sludge bed （EGSB） reactor was adopted to study the influence factors and rule of enhancing granular sludge concentration and performance. The experiment was performed at 33 ℃, pH 6.0-8.0 with continuous flow by adding proper quantity of nutritional trace elements. The results show that SLR was the key of steady operation of EGSB reactor. The increment of the granular sludge was influenced by volume loading rate （VLR）, liquid up-flow velocity and sludge loading rate （SLR）. Concentration of granular sludge increased rapidly when liquid up-flow velocity was over 0.94 m · h^-1 with SLR being at 1.0-2.0 d ^-1. With the propriety parameters： liquid up-flow velocity 2.52 m · h^-1, SLR 1.0-2.2 d^-1 and VLR 8.2-13.1 kg · m ^3 · d^-1, 23 days＇ continuous operation resulted in an increment by over 80% of granular sludge concentration in the EGSB reactor, plus good granular sludge property.