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Biochemical Engineering Journal (v.43, #3)
Degradation of synthetic reactive azo dyes and treatment of textile wastewater by a fungi consortium reactor by Qingxiang Yang; Chunmao Li; Huijun Li; Yuhui Li; Ning Yu (pp. 225-230).
In this paper, two microbial cultures with high decolorization efficiencies of reactive dyes were obtained and were proved to be dominant with fungi consortium in which 21 fungal strains were isolated and 8 of them showed significant decolorization effect to reactive red M-3BE. A 4.5l continuous biofilm reactor was established using the mixed cultures to investigate the decolorization performance and the system stability under the conditions of simulated and real textile wastewater as influents. The optimal nutrient feed to this bioreactor was 0.5gl−1 glucose and 0.1gl−1 (NH4)2SO4 when 30mgl−1 reactive black 5 was used as initial dye concentrations. Dye mineralization rates of 50–75% and color removal efficiencies of 70–80% were obtained at 12h hydraulic retention time (HRT) in this case. Higher glucose concentrations in the influents could significantly improve color removal, but was not helpful for dye mineralization. Besides reactive black 5, the bioreactor could effectively decolorize reactive red M-3BE, acid red 249 and real textile wastewater with efficiency of 65%, 94% and 89%, respectively. In addition, the microbial community on the biofilm was monitored in the whole running process. The results indicated fungi as a dominant population in the decolorization system with the ratio of fungi to bacteria 6.8:1 to 51.8:1 under all the tested influent conditions. Analysis of molecular biological detection indicated that yeasts of genus Candida occupied 70% in the fungal clone library based on 26S rRNA gene sequences.
Keywords: Decolorization; Dye; Bioreactor; Fungi consortium
Effects of physico-chemical factors on the viscosity evolution of anaerobic granular sludge by A. Pevere; G. Guibaud; E. Goin; E. van Hullebusch; P. Lens (pp. 231-238).
The rheological properties of anaerobic granular sludge samples from four full-scale and one lab-scale anaerobic bioreactors were characterized by determining their “limit viscosity” values. These values were deducted from the evolution of the apparent viscosity of granular sludge samples (20mL) at steady shear rate (200s−1) recorded using rotation tests with a wings type measurement cell stirrer Anton-Parr reference: ST24-1D/2V-Q0. The limit viscosity values depended on the applied shear rate, indicating a non-Newtonian behavior of the anaerobic granular sludge types investigated. The effect of variations of physico-chemical parameters such as pH (involving surface charge change), size, surface roughness and TSS content on the evolution of the limit viscosity of an anaerobic granular sludge suspension was investigated. This showed the importance of both quantitative (number of particles in a given volume) as well as qualitative (surface charge or shape) granule-granule interactions on this rheological parameter. Moreover, the origin of the granular sludge strongly influenced the limit viscosity value according with different granules characteristics. This work confirms the ability of the rheological parameter “limit viscosity” as an overall parameter to describe the physico-chemical characteristics (TSS, granulometry, origin, and charge) of anaerobic granular sludge and showed this holds for both sieved (500μm) and unsieved sludges.
Keywords: Rheology; Viscosity; Anaerobic granular sludge
Nutrients release and phosphorus distribution during oligochaetes predation on activated sludge by Yuansong Wei; Hui Zhu; Yawei Wang; Jinfu Li; Peixin Zhang; Ji Hu; Junxin Liu (pp. 239-245).
Release of nitrogen and phosphorus into effluent of activated sludge process was reported in the recent researches of sludge reduction induced by oligochaetes. In this study, batch test and radioisotope32P tracer test were therefore carried out to further investigate nutrients release and phosphorus distribution among supernatant, sludge and worm during predation of oligochaetes on sludge. Results showed that more nutrients release into supernatant occurred in the tests of worms with sterilized sludge than that of worms with activated sludge, and release of nitrogen and phosphorus was few in the tests of worms with activated sludge. Statistical analysis showed that no factor was significantly correlated with phosphorus concentration in the supernatant, but time and worm were only two factors significantly affecting total nitrogen (TN) concentration in the supernatant in the test of worms with activated sludge. Through test of radioisotope32P tracer,32P mainly distributed in activated sludge and supernatant, and more release of32P into the supernatant occurred in the test of sludge with worms. After 24h,32P concentration of supernatant in the test of sludge with worms was 9% higher than that in the test of sludge without worms, and32P concentration of worm increased by 2.7%. Additionally, the release rate of phosphorus into supernatant caused by worm's predation on activated sludge was 0.1211mgTP/gWorm(wet weight)h.
Keywords: Activated sludge; Nutrients release; Oligochaetes; Radioisotope; 32; P tracer; Sludge reduction; Wastewater treatment
Electricity generation from starch processing wastewater using microbial fuel cell technology by Na Lu; Shun-gui Zhou; Li Zhuang; Jin-tao Zhang; Jin-ren Ni (pp. 246-251).
Microbial fuel cells (MFCs) represent a new method for simultaneous wastewater treatment and biological electricity generation. In this study, an air-cathode MFC with membrane electrode assembly was operated over four batch cycles (a total period of 140 d) and results indicated that starch processing wastewater containing 4852mg/l of chemical oxygen demand could be used as substrate to produce electricity with this MFC. Maximum voltage output and power density of 490.8mV and 239.4mW/m2 (a current density of 893.3mA/m2) were approached in the third cycle, which also had the minimum internal resistance of about 120Ω and maximum coulombic efficiency of 8.0%. Removal efficiencies of chemical oxygen demand and ammonia-nitrogen increased as a function of time, and maximum amounted to 98.0% and 90.6%, respectively. Scanning electron microscope image revealed that short rod shaped bacillus were the dominant bacteria on the biofilm of the anode, whose electrochemical activity was proved by cyclic voltammetry. These results demonstrate that starch processing wastewater can be used for power generation in MFCs and also can be treated with high removal efficiencies of chemical oxygen demand and ammonia-nitrogen.
Keywords: Bioreactors; Biocatalysis; Wastewater treatment; Starch; Power generation; Microbial fuel cell
Fluid dynamics investigation of variant impeller combinations by simulation and fermentation experiment by Jian-Ye Xia; Yong-Hong Wang; Si-Liang Zhang; Ning Chen; Peng Yin; Ying-Ping Zhuang; Ju Chu (pp. 252-260).
Fluid dynamics in three bioreactors equipped with different impeller combinations were investigated by Computational Fluid Dynamics (CFD) modeling, and avermectin fermentation experiments by Streptomyces avermitilis were also conducted in these bioreactors. Down-pumping propeller (DPP), 6-curved-blade disc turbine (6CBDT) and 6-arrowy-blade disc turbine (6ABDT) were combined to form different impeller combinations, which were tested in this work. The results of simulation showed that impeller combination consisting of upper two DPP and one bottom 6CBDT could provide the modest flow field environment for avermectin fermentation among the tested impeller combinations. Mass transfer study showed that even if the same impellers were used, different impeller combinations gave different KL a value. It was shown that same “radial flow impeller” such as 6ABDT or 6CBDT used in this work would produce the same shear force in the impeller sweeping zone, but it was different for the “axial flow impeller” such as DPP used in this work, which produced different forces at different mounting positions. The relationship between the fluid dynamics and the fungal cell physiological situation was also discussed based on results of simulation and experiments.
Keywords: Dissolved oxygen; Fluid mechanics; Gas–liquid mass transfer; Mixing; Mycelia fermentation; Shear environment
Synthesis of lauroyl phenolic glycoside by immobilized lipase in organic solvent and its antioxidative activity by Yoshiyuki Watanabe; Mizuka Nagai; Kazuhiro Yamanaka; Kunio Jose; Masato Nomura (pp. 261-265).
Three lauroyl phenolic glycosides were synthesized through the condensation of phenolic glycoside such as arbutin, naringin and phloridzin with lauric acid by immobilized lipase in various organic solvents. The conversion depended on the polarity of the organic solvent used for the reaction. The suppressive effect of each lauroyl phenolic glycoside against the oxidation of linoleic acid was higher than that of the corresponding phenolic glycoside, whereas there was no difference between the DPPH radical scavenging activities of unmodified and lauroyl phenolic glycosides. The antioxidative activity of the glycoside was indicated to depend on the number and the placement of phenolic hydroxyl group exhibiting the activity in the molecule.
Keywords: Phenolic glycoside; Immobilized lipase; Organic solvent; Antioxidative activity; Rate constant
Inulinase overproduction by a mutant of the marine yeast Pichia guilliermondii using surface response methodology and inulin hydrolysis by Xinjun Yu; Ning Guo; Zhenming Chi; Fang Gong; Jun Sheng; Zhe Chi (pp. 266-271).
In this study, in order to isolate inulinase overproducers from the marine yeast Pichia guilliermondii, its cells were treated by using UV light and LiCl. The mutant M-30 with enhanced inulinase production was obtained and was found to be stable after cultivation for 20 generations. Response surface methodology (RSM) was used to optimize the medium compositions and cultivation conditions for inulinase production by the mutant M-30 in liquid fermentation. Inulin, yeast extract, NaCl, temperature, pH for maximum inulinase production by the mutant M-30 were found to be 20.0g/l, 5.0g/l, 20.0g/l, 28°C and 6.5, respectively. Under the optimized conditions, 127.7U/ml of inulinase activity was reached in the liquid culture of the mutant M-30 whereas the predicted maximum inulinase activity of 129.8U/ml was derived from RSM regression. Under the same conditions, its parent strain only produced 48.1U/ml of inulinase activity. This is the highest inulinase activity produced by the yeast strains reported so far. We also found that inulin could be actively converted into monosaccharides by the crude inulinase.
Keywords: Pichia; Inulinase; Mutagenesis; RSM; Overproduction
Supermacroporous hydrophobic affinity cryogels for protein chromatography by Fatma Yılmaz; Nilay Bereli; Handan Yavuz; Adil Denizli (pp. 272-279).
N-Methacryloyl-l-tryptophan (MATrp) containing poly(2-hydroxyethyl methacrylate) based supermacroporous cryogel [PHEMATrp] was prepared for lysozyme purification form chicken egg white. MATrp was synthesized by reacting methacryloyl chloride withl-tryptophan methyl ester and provided hydrophobic functionality to the cryogel. PHEMATrp cryogel with 60–100μm pore size was obtained by free radical polymerization of HEMA and MATrp having a specific surface area of 50m2/g. PHEMATrp cryogel was characterized by swelling studies, FTIR and SEM. The equilibrium swelling ratios of the cryogels were 7.18g H2O/g for PHEMA and 6.99g H2O/g for PHEMATrp. Lysozyme adsorption experiments were investigated under different conditions in continuous system (i.e., medium pH, flow-rate, protein concentration, temperature, salt type). Lysozyme adsorption capacity of PHEMA and PHEMATrp cryogels from aqueous solutions was estimated as 2.9 and 46.8mg/g (0.49 and 7.85mg/mL), respectively. Lysozyme molecules were desorbed with 0.5M ethylene glycol solution with 91% recovery. It was observed that PHEMATrp cryogel can be used without significant decrease in lysozyme adsorption capacity after five adsorption–desorption cycles. PHEMATrp cryogel was used for the purification of lysozyme from chicken egg white. Purity of lysozyme was estimated by SDS-PAGE. Possible denaturation of purified lysozyme was checked with fluorimetric measurements. Specific activity of the purified lysozyme was found as 43,140U/mg using Micrococcus lysodeikticus as substrate.
Keywords: Cryogels; Protein purification; Affinity adsorption; Hydrophobic Interaction Chromatography; Lysozyme
Performance and optimization of biological nitrogen removal process enhanced by anoxic/oxic step feeding by Guibing Zhu; Yongzhen Peng; Liming Zhai; Yu Wang; Shuying Wang (pp. 280-287).
The aim of this paper is to investigate the performance and optimization of an biological nitrogen removal process enhanced by the anoxic/oxic four stages step-feeding process under sufficient/insufficient influent carbon source. The concept of influent flow distribution ratio ( λ) was introduced according to the performance of the step-feed process for inflow splitting and volume distribution. Under the condition of sufficient carbon, the uniform influent flow distribution ratio was proposed from the standpoint of which is easy for process control, operation optimization and management. Under the condition of different influent C/N ratios, the optimal influent flow distribution ratios ( λopt) were determined, by trial-and-error method. The results showed that more than 95.81% of the total nitrogen removal efficiency could be achieved by step-feeding process with a fixed influent C/N ratio. A model was introduced to derive the relationships of total nitrogen removal efficiency with λ and influent C/N ratio. When the influent carbon source was insufficient, however, the λopt between two adjacent stages should not be uniform. The results also showed that the four-stage step-feeding process with λopt of 2.0:2.1:2.5:3.4 could significantly improve the total nitrogen removal efficiency. The results obtained in this study will help to optimize the design and the operation of BNR systems.
Keywords: Enhanced biological nitrogen removal; Optimization; Bioreactors; Bioprocess design; Step-feeding process; Waste water treatment
Maintenance of phosphorus removal in an EBPR system under permanent aerobic conditions using propionate by M. Vargas; C. Casas; J.A. Baeza (pp. 288-296).
Enhanced biological phosphorus removal (EBPR) is an efficient and sustainable technology to remove phosphorus from wastewater preventing eutrophication in natural waters. It is widely accepted that EBPR requires an optimal anaerobic hydraulic retention time to obtain stable P-removal from wastewater. Thus, it is suggested that deterioration of the EBPR efficiency regularly observed in full-scale wastewater treatment plants (WWTPs) is normally caused by an excessive aeration of activated sludge that increments the amount of oxygen recycled to the anaerobic reactor and consequently, the anaerobic conditions are not totally preserved. Furthermore, it has been reported a progressive decrease in P-removal capacity in an EBPR lab-scale system enriched with acetate as the sole carbon source under permanent aerobic conditions. Hence, to evaluate the stability of P-removal with a different carbon source, an EBPR-SBR was operated with propionate under permanent aerobic conditions. As a result, net P-removal was successfully accomplished in the SBR without any anaerobic phase during 46 days of aerobic operation. Moreover, the system was shifted after this period to the standard anaerobic–aerobic conditions and reliable P-removal was maintained. FISH (fluorescence in situ hybridisation) analysis showed a significant presence of Accumulibacter (70, 50 and 72%, in different periods) and the absence of Competibacter. The results indicate that using propionate as carbon source it is possible to maintain in a long term an enriched culture of phosphorus accumulating organisms (PAO) able to remove phosphorus under permanent aerobic conditions.
Keywords: Aerobic processes; Enhanced biological phosphorus removal (EBPR); Phosphorus accumulating organisms (PAO); Propionic acid; Wastewater treatment
Anaerobic treatment of low-strength wastewater with a high fraction of particulate matter in an unconventional two-phase ASBRs system by Andres Donoso-Bravo; Gonzalo Ruiz-Filippi; Rolando Chamy (pp. 297-302).
The results of a two-phase anaerobic system using anaerobic sequencing batch reactors (ASBRs), treating low-strength wastewater (COD∼500mg/L) with a high fraction of particulate organic matter (70%, COD basis), are presented. Two reactors in series were used; the first one was hydrolytic–acidogenic, while the second one was methanogenic. This configuration was proposed to promote high efficiency solids removal. During the experiment, 69% and 50% efficiencies of total COD removal were obtained for OLRs of 0.63 and 1.22kgCOD/(m3d), respectively. Values of the solubilized organic fraction (SOF) achieved in the hydrolytic–acidogenic reactor were within the range of 0.3–0.6gCODsolubilized/gpCODremoved, and the average acidified organic fraction (AOF) was 0.6gCODVFA-produced/gsCODfed. The methanogenic reactor had a VFA removal fraction (VFARF) between 0.4 and 0.6gCODVFA-removed/gCODVFA-fed for the OLR of 0.63 and 1.22. The two-phase ASBR system is suitable, and can be implemented, for the anaerobic treatment of this kind of wastewater.
Keywords: Anaerobic processes; Two-phase system; Anaerobic sequencing batch reactor; Domestic wastewater; Wastewater treatment; Acetic acid
A green low-cost biosynthesis of Sb2O3 nanoparticles by Anal K. Jha; Kamlesh Prasad; K. Prasad (pp. 303-306).
A green low-cost and reproducible yeast ( Saccharomyces cerevisiae) mediated biosynthesis of Sb2O3 nanoparticles is reported. The synthesis is performed akin to room temperature in the laboratory ambience. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of Sb2O3 nanoparticles. Rietveld analysis indicated that Sb2O3 nanoparticles have face centered cubic (FCC) unit cell structure. Individual nanoparticles as well as a few number of aggregate almost spherical in shape having a size of 2–10nm are found. Possible involved mechanism for the synthesis of nano-Sb2O3 has also been proposed.
Keywords: Nanoantimony trioxide; Nanoparticle; Bio-nanotechnology; Green approach
Immobilization of β galactosidase from Aspergillus oryzae via immunoaffinity support by Toshiba Haider; Qayyum Husain (pp. 307-314).
Polyclonal antibody bound cellulose support has been exploited for the immobilization and stabilization of β galactosidase from Aspergillus oryzae. Immunoaffinity bound β galactosidase retained 96.5% of the initial activity on the support. Immobilized β galactosidase showed broad-spectrum pH optima, pH 4.6–5.5 and temperature at 50–60°C whereas the soluble enzyme exhibited activity peak at pH 4.6 and 50°C. Immunoaffinity bound enzyme preparation was quite stable to thermal denaturation and it retained 72% activity after 4h incubation at 60°C whereas under these conditions the soluble β galactosidase lost almost its full activity. IgG-cellulose immobilized β galactosidase was quite stable against the inactivation caused by proteolytic enzymes; trypsin and pepsin. Moreover, this immobilized enzyme preparation retained 64%, 71% and 65% activity in the presence of 4.0M urea, 5% CaCl2 and 5% galactose. IgG-cellulose bound β galactosidase exhibited 80% of its original activity after 2 months storage at 4°C while the soluble enzyme showed only 35% of the initial activity. After 10th repeated use immobilized β galactosidase retained 46% activity.
Keywords: Abbreviations; DEAE; diethyl aminoethyl; PAGE; polyacrylamide gel electrophoresis; SDS; sodium dodecyl sulphate; ELISA; enzyme linked immunosorbent assay; LB; Langmuir–Blodgett; ONPG; o; -nitrophenyl β-; d; -galactopyranoside; TBS; Tris buffer salineβ Galactosidase; Cellulose; Lactose hydrolysis; Immobilization; Stabilization; Polyclonal antibodies
Production of a collagenase from Candida albicans URM3622 by Carolina A. Lima; Priscila M.B. Rodrigues; Tatiana S. Porto; Daniela A. Viana; José L. Lima Filho; Ana L.F. Porto; Maria G. Carneiro da Cunha (pp. 315-320).
Culture conditions (pH, time, temperature, inoculum size, orbital agitation speed and substrate concentration) for an extracellular collagenase produced by Candida albicans URM3622 were studied using three experimental designs (one 26−2 fractionary factorial and two 23 full factorial). The analysis of the 26−2 fractionary design data indicated that agitation speed and substrate concentration had the most significant effect on collagenase production. Based on these results, two successive 23 full factorial design experiments were run in which the effects of substrate concentration, orbital agitation speed and pH were further studied. These two sets of experiments showed that all variables chosen were significant for the enzyme production, with the maximum collagenolytic activity of 6.8±0.4U achieved at pH 7.0 with an orbital agitation speed of 160rpm and 2% substrate concentration. Maximum collagenolytic activity was observed at pH 8.2 and 45°C. The collagenase was stable within a pH range of 7.2–8.2 and over a temperature range of 28–45°C. These results clearly indicate that C. albicans URM3622 is a potential resource for collagenase production and could be of interest for pharmaceutical, cosmetic and food industry.
Keywords: Enzyme activity; Enzyme production; Submerged culture; Protease; Collagenase; Candida albicans
Self-interaction of native and denatured lysozyme in the presence of osmolytes,l-arginine and guanidine hydrochloride by Xiao-Yan Dong; Jian-Hua Liu; Fu-Feng Liu; Yan Sun (pp. 321-326).
Osmolyte molecules such as betaine and trehalose are protein stabilizers whilel-arginine (Arg) and guanidine hydrochloride (GdnHCl) are the most widely used aggregation suppressor in protein refolding. We have herein studied the effects of the osmolyte molecules andl-arginine together with GdnHCl (0–6mol/L) on the intermolecular interaction of native and denatured lysozyme by self-interaction chromatography. The self-interaction is characterized in terms of the osmotic second virial coefficient ( B) of the protein, the increase of which represents the decrease of intermolecular attraction of the protein. It is found that the effect of Arg on the self-interaction of lysozyme is similar with GdnHCl, but its competence is much weaker than the denaturant. At higher GdnHCl concentrations (>0.5mol/L), Arg can be used to suppress the self-association of lysozyme. In contrast to Arg, B increases with increasing betaine or trehalose concentration at the GdnHCl concentration range studied. The results indicate the cooperativity of each osmolyte with GdnHCl, and the different mechanisms of their effects from Arg on the B values. The work confirms that the osmolytes are not only protein stabilizers, but also protein aggregation suppressors for both native and denatured protein molecules.
Keywords: Bioseparations; Protein refolding; Chromatography; Affinity; Self-interaction; Second virial coefficient
Synthesis of ethyl butyrate in organic media catalyzed by Candida rugosa lipase immobilized in polyurethane foams: A kinetic study by P. Pires-Cabral; M.M.R. da Fonseca; S. Ferreira-Dias (pp. 327-332).
A kinetic study on the synthesis of ethyl butyrate in n-hexane, catalyzed by Candida rugosa lipase immobilized in two hydrophilic polyurethane foams (“HYPOL FHP 2002” and “HYPOL FHP 5000”) was performed. With the “FHP5000” foams, esterification rates and conversion were always higher than those obtained with “FHP2002”. For both immobilized preparations, BA did not cause any inhibition on the enzymatic activity, in the range of concentration tested (0.078–0.7M) at an initial ethanol concentration of 0.105M. Michäelis–Menten kinetics was observed: a plateau being reached at the initial bulk BA concentration of 0.40M and 0.45M, corresponding to microenvironmental concentrations of 0.851M and 0.329M, respectively with the lipase in “FHP2002” and “FHP5000” foams. Inhibition by EtOH was observed for initial bulk concentrations higher than 0.15M, corresponding to microenvironmental concentrations of 0.426M and 0.256M, for the lipase in “FHP2002” and “FHP5000” foams, respectively. Kinetic data could be well described by the substrate-inhibition model, considering the initial bulk or microenvironmental ethanol concentrations as inhibitory.
Keywords: Biocatalyst preparation; Enzyme; Immobilized; Kinetics; Lipase; Polyurethane foams
Functional polymeric supports for immobilization of cholesterol oxidase by Berrin Akkaya; Ferat Şahin; Gökhan Demirel; Hayrettin Tümtürk (pp. 333-337).
Here, we have reported the useful functional polymeric supports for possible application of enzyme immobilization. Functional polymers were prepared by free radical polymerization from different monomers (i.e., methylmetacrylate, glycidylmethacrylate, acrylamide, etc.) and N, N-methylenebis(acrylamide) (MBAAm) crosslinker. Cholesterol oxidase (ChOx) [EC.1.1.3.6] was then covalently immobilized onto these functional supports via epichlorohydrin (ECH) and carbodiimide (EDAC) as the activating agents. It was observed that, after 60th use in 5 days, the retained activities for immobilized enzymes onto poly(methyl methacrylate-co-glycidyl methacrylate) [P(MMA-co-GMA)] and poly(acrylamide-co-acrylic acid)/polyethyleneimine [P(AAm-co-AA)/PEI] supports were found as 56% and 83%, respectively.
Keywords: Immobilization; Kinetic parameters; Enzyme stability; Biosensors; Biomaterials; Cholesterol oxidase