Facilitated mass transfer in a packed-bed immobilized-cell reactor by using an organic solvent as substrate reservoir

The production of propene oxide from propene and oxygen by non-growing cells entrapped in calcium alginate was used to study the behaviour of a packed-bed immobilized-cell reactor operated with an organic solvent as the substrate reservoir. As a result of the high solubility of propene in the solvent used, n-hexadecane, oxygen was considered to be the limiting substrate. Dilution of the biocatalyst bed with small glass particles appeared necessary to attain a high liquid/solid contacting efficiency between the hydrophilic gel particles and the hydrophobic solvent. The bed dilution had the advantage of avoiding bed compaction and reducing pressure drops. The use of an organic solvent as the transport medium prevented oxygen depletion along the length of the packed-bed reactor. This eliminated the need for a separate gas phase in the bioreactor. A mathematical reactor model was developed to describe the combined effects of contacting pattern and external and internal diffusion limitations on the instrinsic kinetics of the immobilized cells. Experiments with the packed-bed immobilized-cell reactor were performed using an aqueous solution or n-hexadecane as the reaction medium. Predicted oxygen conversions compared favourably to the observed values without the need for fitting factors.     

Flow rate impact on the performance of immobilized nanoFeCu for sewage treatment and its reusability

Ammonia pollution is a global issue, and it endangers human and aquatic life. The role of nanoFeCu in oxidizing ammonia has been identified, but its practicality and performance on the pilot scale are still unclear. This study was conducted to investigate immobilized nanoFeCu's performance in terms of ammonia, nitrate, nitrite, biological oxygen demand (BOD), chemical oxygen demand (COD), and total suspended solid (TSS) by using sewage as feed. The effect of sewage flow rate was studied to determine the optimum operating condition of a pilot-scale reactor. The reusability test was conducted to address sustainability concerns. The nanoFeCu was synthesized, immobilized in polymer clay, and placed into the reactor filled with sewage at a varied flow rate of from 210 to 1200 mL/min. Results showed that a higher sewage flow rate increased the ammonia removal rate within a shorter time but exhausted the immobilized nanoFeCu at a higher rate. Nitrate, nitrite, and TSS have a similar removal trend as ammonia. 800 mL/min was identified as the optimum flow rate with effluent ammonia concentration below 10 ppm in 9 h and maintained for 12 h. A reusability study showed that immobilized nanoFeCu could be reused for at least 10 successive cycles. The stability and performance of immobilized nanoFeCu suggested that it could be an alternative to treat sewage wastewater for real-life applications.     

基于双级燃料反应器的污泥化学链燃烧特性

化学链燃烧技术是一种可以实现CO₂内分离的新型燃烧技术。本文利用基于双级燃料反应器的新型化学链燃烧反应系统,以赤铁矿为载氧体,对污泥的化学链燃烧进行实验研究,系统连续稳定运行8h,考察燃料反应器温度（800～900℃）、污泥进料量（300～600g/h）对污泥化学链燃烧性能的影响。结果表明,稳定运行过程中,床料大部分位于一级燃料反应器,下降管高度保持稳定;双级燃料反应器的设计极大提高了污泥碳转化率,随温度的增加,碳转化率和碳捕集效率逐渐升高,且额外耗氧量始终低于10%;随着污泥进料量增加,碳转化率和CO₂体积分数逐渐降低。对两级燃料反应器内载氧体进行XRD分析,结果显示,还原后的载氧体在空气反应器再生后进入二级燃料反应器,和一级燃料反应器相比,具有更多的Fe₂O₃成分,保证其具有更高的反应活性。     

Anaerobic-aerobic processes for the treatment of textile dyeing wastewater containing three commercial reactive azo dyes: Effect of number of stages and bioreactor type

In this study, the effect of number of stages and bioreactor type on the removal performance of a sequential anaerobic-aerobic process employing activated sludge for the treatment of a simulated textile dyeing wastewater containing three commercial reactive azo dyes was considered. Two stage processes performed better than one stage ones, both in terms of overall organic and color removal, as well as the higher contribution of anaerobic stage to the overall removal performance, thereby making them a more energy efficient option. The employment of a moving bed sequencing batch biofilm reactor, which uses both suspended and attached biomass, for the implementation of the anaerobic stage of the process, was compared with a sequencing batch reactor that only employs suspended biomass. The results showed that, although there was no meaningful difference in biomass concentration between the two bioreactors, the latter reactor had better performance in terms of chemical oxygen demand (COD) removal efficiency and rate and color removal rate. Further exploratory tests revealed a difference between the roles of suspended and attached bacterial populations, with the former yielding better color removal whilst the latter had better COD removal performance. The sequential anaerobic-aerobic process, employing an aerobic membrane bioreactor in the aerobic stage resulted in COD and color removal of 77.1±7.9% and 79.9±1.5%, respectively. The incomplete COD and color removal was attributed to the presence of soluble microbial products in the effluent and the autoxidation of dye reduction metabolites, respectively. Also, aerobic partial mineralization of the dye reduction metabolites, was experimentally observed.     

Model for biodegradation of a naphthenic acid in an immobilized cell reactor

Previously, using maximum feed concentrations of 500 mg/L, an immobilized cell reactor (ICR) with established biofilm was shown to enhance the biodegradation rate of a candidate naphthenic acid up to two orders of magnitude when compared to a freely suspended cell, well mixed tank reactor, reaching biodegradation rates of 22 000 mg/L day with 100% biodegradation efficiencies [Paslawski et al., J. Chem. Technol. Biotechnol. 2009a]. In this work, dispersion in the ICRs was found to be negligible and a plug flow model was developed and shown to represent the immobilized cell biodegradation data well. The effectiveness coefficient (percent of dry biofilm containing active biomass) was predicted to be approximately 55% with an effective thickness of 0.15 mm.     

海藻酸钠包埋高效菌种强化处理聚酯废水的试验研究

对海藻酸钠-氯化钙法包埋某高效微生物菌种用于强化聚酯废水的生物处理进行了试验研究,同时将其与普通系统和高效菌种的悬浮投加型强化系统作了相应比较.结果表明:相对普通系统,悬浮投加高效菌种可使出水COD降低100mg/L,处理率提高8%,而用海藻酸钠-氯化钙法包埋固定化之后投加则可使出水COD降低200mg/L,处理率提高14%,使最终出水COD达到100mg/L以下,达到出水的排放要求,且减少了废水中对人类和环境有较大危害的1,4-二氧杂环己烷的含量.     

Production of berberine in immobilized plant cell culture ofThalictrum rugosum

Thalictrum rugosum cells were immobilized in calcium alginate, where they continued to live with their biological activity. The immobilized living cells performed the production of berberine in both shake flasks and an airlift bioreactor. Berberine formation was growth associative and most of the berberine produced was stored intracellularly. Rapid hydrolysis of sucrose and preference of glucose over fructose during the growth stage was observed. Phosphate-deficient media increased berberine production and prevented the dissolution of alginate beads. The behavior of immobilized cells grown in an airlift reactor was compared with that of the corresponding shake flask culture with respect to growth and berberine production. The rate of cell growth and berberine production in an airlift reactor operation was higher than those in packedcolumn reactor operation due to a better oxygen transfer.     

Enhancement of Coagulation Flocculation Process Using Anionic Polymer for the Post Treatment of UASB Reactor Effluent

This study was conducted for the treatment of up-flow anaerobic sludge blanket (UASB) reactor effluent by polymer assisted coagulation–flocculation process. The efficiency of alum, FeCl₃, and polyaluminum chloride (PAC) was observed alone and in coupled with anionic polymer (Synpol). The results revealed that FeCl₃ and PAC are efficient to remove 99% of turbidity, 83% of total suspended solids (TSS), 82% and 85% of biochemical oxygen demand (BOD) and chemical oxygen demand (COD), respectively, and 99.5% removal of total coliforms (TC) and fecal coliforms (FC). The addition of anionic polymer to alum, FeCl₃, and PAC reduces the sludge volume upto 25%.     

双级燃料反应器的煤化学链燃烧特性

在5 kW_th双级燃料反应器的化学链燃烧装置上,开展煤化学链燃烧特性研究,重点考察反应温度和气化介质对燃烧补偿率、碳增补率、出口气体组分浓度、额外耗氧率以及碳捕集效率的影响规律。实验结果表明,较高的反应温度能显著提高燃烧效率,900℃时出口烟气中CO₂浓度可达92.1%;随着反应温度升高,碳捕集率和燃烧补偿率分别上升至99.6%和83.4%,额外耗氧率和碳增补率下降至12.1%和4.8%。以CO₂为气化介质时,整体反应效率有大幅下降,额外耗氧率提高至23%。此外,在Ⅰ级FR反应器内发现有少量的团聚颗粒,但并未对流化产生影响。     

Comparative study of nitrification performances of immobilized cell fluidized bed reactor and contact oxidation biofilm reactor in treating high strength ammonia wastewater

BACKGROUND: The immobilized cell fluidized bed reactor and contact oxidation biofilm reactor are two common choices for high strength ammonia wastewater treatment, however, comparative study of the nitrification performance of the two reactors has not been thoroughly studied. The nitrification performance of the two bioreactors when treating strong synthetic ammonia wastewater was investigated and compared. RESULTS: Results demonstrated that the immobilized cell fluidized bed reactor had a shorter acclimation period, and possessed several advantages over the contact oxidation biofilm reactor, in the form of complete oxidation of 150–360 mg L^?1 ammonia wastewater in a shorter time, higher ammonia removal rates (from 9.6 to 4.32 × 10² mgN L^?1 d^?1) over the temperature range 8 to 32 °C, irrespective of organic load. In contrast, a large reduction in ammonia removal was found in the contact oxidation biofilm reactor with chemical oxygen demand (COD) load. The immobilized cell fluidized bed reactor exhibited stable and high rates of nitrification in the long term. CONCLUSION: These facts demonstrated that the immobilized cell fluidized bed reactor is a suitable selection for high strength ammonia wastewater treatment. Copyright © 2007 Society of Chemical Industry     

新型生物流化床中悬浮相微生物与附着相微生物的共存研究

针对新型好氧内循环三相生物流化床反应器处理污水的特性,对反应器中悬浮生长微生物和附着生长微生物的共存关系进行了研究.结果表明,生物膜厚度随反应器有机负荷的提高而增大;随反应器悬浮状态MLSS的增加而减小,但这些因素对生物膜总量影响不大.生物膜厚度还随反应器循环液速和气含率的增大而减小,这主要是因为水力剪切作用使生物膜厚度减小.总生物量的增加对COD的去除有利,而NH3-N的去除主要依靠悬浮生长的微生物.     

Mixing characteristics and performance of the anaerobic upflow blanket filter (UBF) reactor

Mixing characteristics (using a radioactive tracer) and reactor performance of the upflow blanket filter (UBF) reactor operated at different loading rates (up to 32 kg chemical oxygen demand (COD) m^?3 day^?1) were compared. The results indicated that mixing profiles of the reactor operated with effluent recirculation and without biomass were of the perfectly mixed type. Operation without recirculation resulted in about 18% dead space. The filter made of plastic rings and located in the top third of the reactor had no negative effect on reactor mixing. Operation at loading rates of up to 25 kg COD m^?3 day^?1 permitted a soluble COD removal rate of 95% with a methane production rate of 5.9 m³ m^?3 day^?1. At higher loading rates, the efficiency of COD reduction decreased with a decrease of the specific acetoclastic activity to 0.5 kg acetate removed per kg volatile suspended solids (VSS) day^?1. At all loading rates studied it was observed that the performance was not related to the mixing characteristics, which had remained of the perfectly mixed type with an occasional small dead space (below 10%). The good mixing characteristics of the UBF reactor coupled with the high biomass content and the effective action of the filter make this reactor one of the most promising designs for the treatment of soluble wastes.     

A／O生物膜反应器处理生活污水的实验研究

A／O生物膜实验系统中，缺氧反应器填充半软性填料，好氧反应器填充悬浮填料。用人工模拟污水考察了反应器的脱碳、脱氮性能。研究了HRT、回流比R等参数对系统废水处理效率的影响，探讨了反应器的脱氮机理。     

Hydrolysis of Penicillin G by Penicillin G Acylase Immobilized on Chitosan Microbeads in Different Reactor Systems

The kinetic parameters for penicillin G hydrolysis in systems with penicillin G acylase from Escherichia coli (free and immobilized on activated chitosan microbeads produced by electrostatic extrusion) were determined. The obtained kinetic results indicated that both systems (free and immobilized) are inhibited by high concentrations of the substrate (penicillin G) as well as by products of the reaction (6‐aminopenicillanic acid and phenylacetic acid). The microbeads appeared convenient for penicillin G acylase immobilization reducing negative inhibitory effects. The hydrolysis was also investigated in a packed bed reactor. The derived kinetic model predicted good hydrolysis rates in the reactor while the system with recirculation of the reaction mixture proved to be a potentially favorable solution providing operation at low shear stresses and possibly higher hydrolysis rates than in the packed bed reactor alone.     

Application of chitosan‐entrapped β‐galactosidase in a packed‐bed reactor system

The model enzyme β‐galactosidase was entrapped in chitosan gel beads and tested for hydrolytic activity and its potential for application in a packed‐bed reactor. The chitosan beads had an enzyme entrapment efficiency of 59% and retained 56% of the enzyme activity of the free enzyme. The Michaelis constant (K_m) was 0.0086 and 0.011 μmol/mL for the free and immobilized enzymes, respectively. The maximum velocity of the reaction (V_max) was 285.7 and 55.25 μmol mL^?1 min^?1 for the free and immobilized enzymes, respectively. In pH stability tests, the immobilized enzyme exhibited a greater range of pH stability and shifted to include a more acidic pH optimum, compared to that of the free enzyme. A 2.54 × 16.51‐cm tubular reactor was constructed to hold 300 mL of chitosan‐immobilized enzyme. A full‐factorial test design was implemented to test the effect of substrate flow (20 and 100 mL/min), concentration (0.0015 and 0.003M), and repeated use of the test bed on efficiency of the system. Parameters were analyzed using repeated‐measures analysis of variance. Flow (p < 0.05) and concentration (p < 0.05) significantly affected substrate conversion, as did the interaction progressing from Run 1 to Run 2 on a bed (p < 0.05). Reactor stability tests indicated that the packed‐bed reactor continued to convert substrate for more than 12 h with a minimal reduction in conversion efficiency. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1294–1299, 2004     

Production of low methoxyl pectin using immobilized pectinmethylesterase silica from acerola (Malpighia glabra L.)

The aim of this work was to develop an efficient reactor for the production of low methoxyl pectin, using pectinmethylesterase (PME, EC 3.1.1.11) from acerola immobilized on silica. The immobilized enzyme was used in up to 50 successive bioconversion runs at 50 °C with an efficiency loss of less than 20%. The fixed‐bed reactor (6.0 × 1.5 cm) was prepared using PME immobilized in glutaraldehyde‐activated silica operated at 50 °C with an optimum flow rate of 10 mL h^?1. The bioconversion yield was shown to strongly depend on the nature of the enzymatic preparation. An efficiency of 44% was achieved when concentrated PME was used, compared with only 30% with purified PME, both after an 8‐h run. The process described could provide the basis for the development of a commercial‐scale process. Copyright © 2006 Society of Chemical Industry     

Photocatalytic decolorization of rhodamine B by immobilized TiO2/UV in a fluidized-bed reactor

The photocatalytic oxidation of Rhodamine B (RhB) was studied by using a newly developed immobilized photocatalyst (TiO₂ immobilized by support consisting of a perlite and silicone sealant) and a fluidized-bed reactor. Three 8W germicidal lamps were used as the light source and the reactor volume was 2.8l. When this photocatalyst was employed in a batch process, a total decolorization of the RhB in reaction times lower than 60 min was observed. The optimum dosage of photocatalyst was 33.8 g/l. The initial RhB decolorization rate of the immobilized TiO₂ was higher than that of the suspended TiO₂ and this did not agree with pseudo first-order kinetics because of the adsorption onto the surface of the immobilized TiO₂. This result indicated that the adsorption capacity of the immobilized photocatalyst is very important in photocatalysis.     

太阳能固定膜光催化反应器的效率评价

以结构简单、光能利用率高的复合抛物面采光板为采光元件,以采用溶胶-凝胶法负载在比表面积大、化学性质稳定的玻璃纤维网上制得的高活性TiO₂固定催化剂制作催化组件,自主设计了一种新型的太阳能光催化反应器。以草酸铁钾化学光量计曝光试验对其光学性能进行了评价,光子采集效率约为0.759。由于固定化催化剂活性良好、装填结构合理,本装置降解苯酚表观量子产率可以达到相同结构悬浆催化体系反应器的1/2,因而具有良好的实用性。     

厌氧-膜过滤联用工艺处理屠宰废水的研究

采用完全混合型厌氧生物反应器处理高悬浮物含量的屠宰废水,并经过外置错流式超滤膜组件进行泥水分离。研究表明该系统具有很短的启动期,稳定运行后在不同容积负荷条件下均能取得很高的有机物去除率,在半年运行期内对化学需氧量(COD)的平均去除率为91.65%,系统的最高COD容积负荷可达到8.0 g/(L.d);稳定运行期间系统去除COD的甲烷产率处于0.20—0.30 L/g。该工艺实现了厌氧污泥与进水悬浮物的完全截留,对高悬浮性的复杂工业废水具有很好的处理效果。     

外循环对IC反应器运行效果的影响

为改善已形成颗粒污泥的IC反应器运行性能,增设外循环装置,并在回流比分别为0、1.0、2.0、3.0、4.0的情况下,进行了系统运行稳定性研究。与无外循环的情况相比,在设定的回流比范围内,附加外循环不会破坏反应器内部厌氧条件,反应器运行稳定;在进水COD为6000 mg·L^-1左右,系统HRT约为10 h,容积负荷为14 kg·m^-3·d^-1的情况下,系统污泥MLSS有所增加,COD去除率随回流比的增大而增加,最高可达97.3%,出水COD低至160 mg·L^-1;随回流比的增大,产气总量逐渐增加且最终可达171.2 L·d^-1,甲烷产量先增加后趋于稳定,在回流比为2.0时可达到91.7 L·d^-1;增加外循环运行一段时间后,厌氧颗粒污泥生物相更为丰富,产甲烷优势菌由甲烷杆菌转变为甲烷八叠球菌。结合能耗和去除效率等考虑,回流比为2.0时最佳。