Fabrication of an ultra-sensitive electrochemical DNA biosensor based on CT-DNA/NiFe2O4NPs/Au/CPE for detecting rizatriptan benzoate.

A novel and first electrochemical biosensor based on Deoxyribonucleic acid (DNA) as a biological component to measure an antimigraine drug, rizatriptan benzoate (RZB) for patients under treatment in biological samples was developed. A carbon paste electrode (CPE) was modified by calf thymus (CT) double-stranded (ds)-DNA, nickel ferrite magnetic nanoparticles (NiFe2O4NPs), and gold nanoparticles (AuNPs). The morphology of the CT-DNA/NiFe2O4NPs/AuNPs/CPE was characterized by Field emission scanning electron microscope (FESEM). The presence of NiFe2O4NPs and AuNPs was confirmed by energy-dispersive X-ray spectroscopy (EDS) image of the NiFe2O4NPs/AuNPs/CPE surface. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to determine the structure and electrochemical characteristics of the CT-DNA/NiFe2O4NPs/AuNPs/CPE. Differential pulse voltammetry (DPV) was used to investigate the electrochemical behavior of RZB. Chronoamperometry (CA) was applied to study the effect of CT-DNA immobilization time on the peak oxidation current of RZB accumulated on the surface of the CT-DNA/NiFe2O4NPs/AuNPs/CPE. The results showed that, under optimum conditions, the prepared electrode responded linearly to RZB concentrations between 0.01 and 2.0 µM, with a 0.0033 µM detection limit (LOD) and 0.01 µM limit of quantification (LOQ). The parameters influencing the biosensor performance (temperature, CT-DNA immobilization time, and RZB/CT-DNA accumulation time) were optimized. DPV showed the displacement of the peak potential towards positive values and the reduction of its current, indicating that the drug could intercalate between the guanine base pairs of CT-DNA. Our biosensor was successfully applied for RZB measurement in human urine, blood serum, plasma samples, and tablets. The presented biosensor was fast response, sensitive, selective, cost-effective, and easy-to-use for RZB determination in pharmaceutical formulations and biological samples.

North by Southwest: Screening the Naturally Isolated Microalgal Strains from Different Habitats of Iran for Various Pharmaceutical and Biotechnology Applications.

Background and Aims: Microalgae are known as a promising source for food, pharmaceutical, and biofuel production while providing environmental advantages. The present study evaluates some newly isolated microalgal strains from north and southwest of Iran as a potential source for high-value products. Methods: Primitive screening was carried out regarding growth parameters. The molecular and morphological identifications of the selected strains were performed using 18S rRNA gene sequencing. After phylogenic and evolutionary studies, the selected microalgal strains were characterized in terms of protein and pigment content, in addition to the fatty acid profile content. Besides, the CO2 fixation rate was determined to assess capability for various environmental applications. Results: All of the selected strains were predominantly belonging to Scenedesmus sp. and Desmodesmus sp. The isolated Scenedesmus sp. VN 009 possessed the highest productivity content and CO2 fixation rate of 0.054 g·L-1d-1 and 0.1 g·L-1d-1, respectively. Moreover, data from GC/MS analysis demonstrated the high robustness of this strain to produce several valuable fatty acids including α-linolenic acid and linoleic acid in 45% and 20% of total fatty acids. Conclusions: The identified strains have a great but different potential for SCP, ß-carotene, and ω-3 production, as well as CO2 fixation for environmental purposes. In this study, considering the wide range of microalgal strains in different habitats of Iran, the potential applications of native microalgae for various pharmaceutical, food, and biotechnology purposes were investigated.

Antiinfective properties of ursolic acid-loaded chitosan nanoparticles against Staphylococcus aureus.

The present study aimed to synthesize ursolic acid-loaded chitosan nanoparticles (UA-Ch-NPs) as an antiinfective agent against 21 Staphylococcus aureus isolates. The UA-Ch-NPs were synthesized by a simple method and then characterized by TEM, FTIR, DLS-zeta potential, and XRD analyses. According to the characterization results, highly dispersed spherical nanoparticles with a mean diameter of 258 nm and a zeta potential of + 40.1 mV were developed. The antibacterial properties of UA-Ch-NPs were investigated and their inhibitory effect on biofilm formation was demonstrated by AFM. Finally, the expression levels of icaA and icaD were measured using real-time PCR. Results indicated that the minimum inhibitory concentration (MIC) of UA and UA-Ch-NPs against S. aureus was 64 and 32 µg/mL, respectively. The treatment of bacterial cells with UA-Ch-NPs significantly decreased the expression of icaA and icaD genes which are engaged in biofilm formation. Our results indicated that UA-Ch-NPs could be a promising material for antibacterial and antibiofilm applications.

Simultaneous voltammetric determination of rizatriptan and acetaminophen using a carbon paste electrode modified with NiFe2O4 nanoparticles.

Nickel-ferrite nanoparticles (NiFe2O4) were synthesized by a hydrothermal method. They were used to modify a carbon paste electrode (CPE) and to prepare an electrochemical sensor for simultaneous determination of rizatriptan benzoate (RZB) and acetaminophen (AC). The structure and morphology of the bare CPE and modified CPE were studied using field emission scanning electron microscopy, while the structural characterization of NiFe2O4 was performed via X-ray diffraction. In the potential range 0.2-1.2 V, AC and RZB were detected at potentials of 0.5 V and 0.88 V (vs. Ag/AgCl saturated KCl 3 M), respectively. Both calibration plots are linear in the 1 to 90 µM concentration range. The limits of detection (at 3σ) of AC and RZB are 0.49 and 0.44 µM, respectively. The performance of the modified CPE was evaluated by quantifying the two drugs in spiked urine and in tablets. Graphical abstract The modified electrode consist of Nickel-ferrite and graphite by differential pulse voltammetry methods are schematically presented for simultaneous detection of acetaminophen (a painkiller drug) and rizatriptan benzoate (an antimigraine drug) in human urine and tablet samples.

Fabrication and evaluation of carboxymethylated diethylaminoethyl cellulose microcarriers as support for cellular applications.

Cellulose based microcarriers can be used in biomedical science as supports for cell adhesion and proliferation. However, to facilitate cell attachment to their surface, they require appropriate functional surface charge. Cell function such as adhesion and growth is increased on the modified surfaces with cationic and anionic groups. In this research, diethylaminoethyl cellulose was carboxymethylated to produce soluble multifunctional cellulose with simultaneous presence of cationic and anionic functional groups. Then, carboxymethylated diethylaminoethyl cellulose (CM-DEAEC) were produced by ionic crosslinking. Various instrumental techniques were applied to characterize the microcarriers. Biological tests were also performed to determine cell seeding efficiency, proliferation and attachment on microcarriers. Fabricated CM-DEAEC microcarriers had 1500-1800 µm diameter, +26.0 surface potential, 376% swelling behavior and 233 °C glass transition temperature respectively. The findings showed that CM-DEAEC microcarriers support cellular attachment and proliferation very well and hence are promising materials for cell therapy and tissue engineering applications.

Single-Layer Assembly of Multifunctional Carboxymethylcellulose on Graphene Oxide Nanoparticles for Improving in Vivo Curcumin Delivery into Tumor Cells.

Nanodrug delivery systems are considered as promising therapeutic platforms to convey drugs to tumor cells. In this study, a single layer of carboxymethylcellulose (CMC) and poly N-vinylpyrrolidone (PVP) was cross-linked through disulfide bond and deposited on graphene oxide nanoparticles (GO NPs) using layer-by-layer technique. Overexpression of folate receptors on tumor cells is a great hallmark for drug delivery systems; though the NPs were functionalized by monoclonal folic acid antibody (FA) using polyethylene glycol (PEG) as linker. The mean diameter of synthesized nanoparticles was 60 nm. Curcumin was encapsulated within CMC layer with high encapsulation capacity of 94%. In vitro investigation showed 87% curcumin release at simulated tumor environment. Curcumin loaded FA modified CMC/PVP GO NPs showed high inhibition of 76 and 81% against Saos2 and MCF7 cell lines in vitro. In vivo investigations on 4T1 bearing breast cancer mice model exhibited 76% antitumor efficiency via active targeting mechanism of folate mediated transport without any significant side effect. Immunohistochemistry and immunofluorescence analyses showed enhanced antiangiogenesis, apoptosis and tumor growth inhibition.

CO2 bio-fixation and biofuel production in an airlift photobioreactor by an isolated strain of microalgae Coelastrum sp. SM under high CO2 concentrations.

Microalgae cultivation is a promising approach to remove ambient CO2 via photosynthesis process. This paper investigates the impact of high CO2 concentrations (6, 12, and 16%) on algae growth, CO2 biofixation, lipid and carbohydrate contents, and nutrient removal of newly isolated microalgae, Coelastrum sp. SM. In addition, the ability of microalgae to produce biodiesel at optimal condition was studied. The microalgae were cultivated in wastewater using an airlift photobioreactor. Under 12% CO2, the maximum biomass productivity and CO2 fixation rate were 0.267 g L-1 day-1 and 0.302 g L-1 h-1, respectively. Total Kjeldahl nitrogen (TKN), total phosphorous (TP), nitrate, and sCOD removal efficiency were 84.01, 100, 86.811, and 73.084%, respectively. Under 12% CO2 and at the same condition for cell growth, the highest lipid and carbohydrate contents were 3 7.91 and 58.45%, respectively. The composition of fatty acids methyl ester (FAME) of the microalga lipid was defined. Based on the obtained results and FAME profile, Coelastrum sp. SM was a suitable feedstock for biodiesel production and also, the organism had a great potential for CO2 biofixation, which is also more suitable than any other reported strains in other related studies.

Cultivation of newly isolated microalgae Coelastrum sp. in wastewater for simultaneous CO2 fixation, lipid production and wastewater treatment.

Cultivation of microalgae in wastewater is a promising and cost-effective approach for both CO2 biofixation and wastewater remediation. In this study, a new strain of Coelastrum sp. was isolated from cattle manure leachate. The isolated microalgae were then cultivated in wastewater. Effects of different sCOD concentrations (600, 750, 900, 1050 mg L-1) and light intensities (1000, 2300, 4600, 6900 and 10000 Lux) on biomass production, CO2 consumption rate and nutrient removal from wastewater were investigated. The results showed that maximum cell growth and CO2 consumption rate were 2.71 g L-1 and 53.12 mg L-1 day-1, respectively, which were obtained in the wastewater with 750 mg L-1 sCOD and under the light intensity of 6900 Lux. The microalgae were able to completely consume all CO2 after incubation period of 4 days. The highest sCOD, total Kjeldahl nitrogen (TKN), nitrate and total phosphorous (TP) removal at such conditions were 53.45, 91.18, 87.51 and 100%, respectively. The lipid content of microalgal biomass was also measured under different light intensities; maximum amount of lipid was determined to be 50.77% under illumination of 2300 Lux. Finally, the CO2 consumption rate and biomass productivity of microalgae in semi-batch culture with continuous gas flow (CO2 6%:N2 94%) were investigated. The rate of CO2 consumption and biomass productivity were 0.528 and 0.281 g L-1 day-1, respectively. The TKN, nitrate, TP and sCOD removal rate of microalgae were 83.51, 80.91, 100, 41.4%, respectively.

Growth kinetic models of five species of Lactobacilli and lactose consumption in batch submerged culture

Abstract Kinetic behaviors of five Lactobacillus strains were investigated with Contois and Exponential models. Awareness of kinetic behavior of microorganisms is essential for their industrial process design and scale up. The consistency of experimental data was evaluated using Excel software. L. bulgaricus was introduced as the most efficient strain with the highest biomass and lactic acid yield of 0.119 and 0.602 g g-1 consumed lactose, respectively. The biomass and carbohydrate yield of L. fermentum and L. lactis were slightly less and close to L. bulgaricus. Biomass and lactic acid production yield of 0.117 and 0.358 for L. fermentum and 0.114 and 0.437 g g-1 for L.actobacillus lactis were obtained. L. casei and L. delbrueckii had the less biomass yield, nearly 11.8 and 22.7% less than L. bulgaricus, respectively. L. bulgaricus (R 2 = 0.9500 and 0.9156) and L. casei (R 2 = 0.9552 and 0.8401) showed acceptable consistency with both models. The investigation revealed that the above mentioned models are not suitable to describe the kinetic behavior of L. fermentum (R 2 = 0.9367 and 0.6991), L. delbrueckii (R 2 = 0.9493 and 0.7724) and L. lactis (R 2 = 0.8730 and 0.6451). Contois rate equation is a suitable model to describe the kinetic of Lactobacilli. Specific cell growth rate for L. bulgaricus, L. casei, L. fermentum, L. delbrueckii and L. lactis with Contois model in order 3.2, 3.9, 67.6, 10.4 and 9.8-fold of Exponential model.

Enantioselective synthesis of (S)-naproxen using immobilized lipase on chitosan beads.

S-naproxen by enantioselective hydrolysis of racemic naproxen methyl ester was produced using immobilized lipase. The lipase enzyme was immobilized on chitosan beads, activated chitosan beads by glutaraldehyde, and Amberlite XAD7. In order to find an appropriate support for the hydrolysis reaction of racemic naproxen methyl ester, the conversion and enantioselectivity for all carriers were compared. In addition, effects of the volumetric ratio of two phases in different organic solvents, addition of cosolvent and surfactant, optimum pH and temperature, reusability, and inhibitory effect of methanol were investigated. The optimum volumetric ratio of two phases was defined as 3:2 of aqueous phase to organic phase. Various water miscible and water immiscible solvents were examined. Finally, isooctane was chosen as an organic solvent, while 2-ethoxyethanol was added as a cosolvent in the organic phase of the reaction mixture. The optimum reaction conditions were determined to be 35 °C, pH 7, and 24 h. Addition of Tween-80 in the organic phase increased the accessibility of immobilized enzyme to the reactant. The optimum organic phase compositions using a volumetric ratio of 2-ethoxyethanol, isooctane and Tween-80 were 3:7 and 0.1% (v/v/v), respectively. The best conversion and enantioselectivity of immobilized enzyme using chitosan beads activated by glutaraldehyde were 0.45 and 185, respectively.

Acid pretreatment and enzymatic saccharification of brown seaweed for polyhydroxybutyrate (PHB) production using Cupriavidus necator.

The brown seaweed Sargassum sp. was used as a feedstock to produce polyhydroxybutyarte (PHB) using Cupriavidus necator PTCC 1615. In order to release monomeric sugars, dilute acid hydrolysis of Sargassum sp. biomass was followed by enzymatic saccharification. In addition, the effect of different nitrogen sources was evaluated for PHB production. The fermentation of hydrolysate with the ammonium sulfate as selected nitrogen source resulted PHB yield of 0.54±0.01g/g reducing sugar. Then, NaCl was used as external stress factor which was added to the media. Addition of 8g/L NaCl had a positive impact on high PHB yield of 0.74±0.01g/g reducing sugar. Increasing trend of NaCl concentration to 16g/L was found to inhibit the production of PHB. Based on obtained results using 20g/L of reducing sugar, at desired condition the highest cell dry weight and PHB concentrations were 5.36±0.22 and 3.93±0.24g/L, respectively. The findings of this study reveal that Sargassum sp. is a promising feedstock for biopolymer production. The characteristics of produced PHB were analyzed by FTIR, differential scanning calorimetry and 1H NMR.

Growth kinetic models of five species of Lactobacilli and lactose consumption in batch submerged culture.

Kinetic behaviors of five Lactobacillus strains were investigated with Contois and Exponential models. Awareness of kinetic behavior of microorganisms is essential for their industrial process design and scale up. The consistency of experimental data was evaluated using Excel software. L. bulgaricus was introduced as the most efficient strain with the highest biomass and lactic acid yield of 0.119 and 0.602gg-1 consumed lactose, respectively. The biomass and carbohydrate yield of L. fermentum and L. lactis were slightly less and close to L. bulgaricus. Biomass and lactic acid production yield of 0.117 and 0.358 for L. fermentum and 0.114 and 0.437gg-1 for L.actobacillus lactis were obtained. L. casei and L. delbrueckii had the less biomass yield, nearly 11.8 and 22.7% less than L. bulgaricus, respectively. L. bulgaricus (R2=0.9500 and 0.9156) and L. casei (R2=0.9552 and 0.8401) showed acceptable consistency with both models. The investigation revealed that the above mentioned models are not suitable to describe the kinetic behavior of L. fermentum (R2=0.9367 and 0.6991), L. delbrueckii (R2=0.9493 and 0.7724) and L. lactis (R2=0.8730 and 0.6451). Contois rate equation is a suitable model to describe the kinetic of Lactobacilli. Specific cell growth rate for L. bulgaricus, L. casei, L. fermentum, L. delbrueckii and L. lactis with Contois model in order 3.2, 3.9, 67.6, 10.4 and 9.8-fold of Exponential model.

Piperine-The Bioactive Compound of Black Pepper: From Isolation to Medicinal Formulations.

Piperine is the major bio-active component of pepper, which imparts pungency and biting taste to it. This naturally occurring alkaloid has numerous demonstrated health effects and beneficial therapeutic properties; nevertheless, its biological applications are limited due to its poor solubility in aqueous environments. This emphasizes an implementation of advanced extraction approaches which could enhance the extraction yield of piperine from pepper and also the development of new formulations containing piperine to improve its in vivo bioavailability. This paper presents a review on the therapeutic and medicinal effects of piperine, its isolation from pepper fruit and the development of new formulations for its medicinal (pharmaceutical) applications. A thorough review on conventional and advanced separation techniques for the extraction of piperine from pepper is presented and an outline of the most significant conditions to improve the extraction yield is provided and discussed. Different methods used to measure and quantify the isolated piperine are also reviewed. An overview of biotechnological advancements for nanoparticle formulations of piperine or its incorporation in lipid formulations, which could enhance its bioavailability, is also presented.

Mathematical modeling of continuous ethanol fermentation in a membrane bioreactor by pervaporation compared to conventional system: Genetic algorithm.

In this paper, genetic algorithm was used to investigate mathematical modeling of ethanol fermentation in a continuous conventional bioreactor (CCBR) and a continuous membrane bioreactor (CMBR) by ethanol permselective polydimethylsiloxane (PDMS) membrane. A lab scale CMBR with medium glucose concentration of 100gL(-1) and Saccharomyces cerevisiae microorganism was designed and fabricated. At dilution rate of 0.14h(-1), maximum specific cell growth rate and productivity of 0.27h(-1) and 6.49gL(-1)h(-1) were respectively found in CMBR. However, at very high dilution rate, the performance of CMBR was quite similar to conventional fermentation on account of insufficient incubation time. In both systems, genetic algorithm modeling of cell growth, ethanol production and glucose concentration were conducted based on Monod and Moser kinetic models during each retention time at unsteady condition. The results showed that Moser kinetic model was more satisfactory and desirable than Monod model.

Immobilized Kluyveromyces marxianus cells in carboxymethyl cellulose for production of ethanol from cheese whey: experimental and kinetic studies.

Cheese whey fermentation to ethanol using immobilized Kluyveromyces marxianus cells was investigated in batch and continuous operation. In batch fermentation, the yeast cells were immobilized in carboxymethyl cellulose (CMC) polymer and also synthesized graft copolymer of CMC with N-vinyl-2-pyrrolidone, denoted as CMC-g-PVP, and the efficiency of the two developed cell entrapped beads for lactose fermentation to ethanol was examined. The yeast cells immobilized in CMC-g-PVP performed slightly better than CMC with ethanol production yields of 0.52 and 0.49 g ethanol/g lactose, respectively. The effect of supplementation of cheese whey with lactose (42, 70, 100 and 150 g/l) on fermentative performance of K. marxianus immobilized in CMC beads was considered and the results were used for kinetic studies. The first order reaction model was suitable to describe the kinetics of substrate utilization and modified Gompertz model was quite successful to predict the ethanol production. For continuous ethanol fermentation, a packed-bed immobilized cell reactor (ICR) was operated at several hydraulic retention times; HRTs of 11, 15 and 30 h. At the HRT of 30 h, the ethanol production yield using CMC beads was 0.49 g/g which implies that 91.07 % of the theoretical yield was achieved.

Kinetic studies on fermentative production of biofuel from synthesis gas using Clostridium ljungdahlii.

The intrinsic growth, substrate uptake, and product formation biokinetic parameters were obtained for the anaerobic bacterium, Clostridium ljungdahlii, grown on synthesis gas in various pressurized batch bioreactors. A dual-substrate growth kinetic model using Luong for CO and Monod for H2 was used to describe the growth kinetics of the bacterium on these substrates. The maximum specific growth rate (µ(max) = 0.195 h(-1)) and Monod constants for CO (K s,CO = 0.855 atm) and H2 (K(s,H2) = 0.412 atm) were obtained. This model also accommodated the CO inhibitory effects on cell growth at high CO partial pressures, where no growth was apparent at high dissolved CO tensions (P(CO)(∗) > 0.743 atm). The Volterra model, Andrews, and modified Gompertz were, respectively, adopted to describe the cell growth, substrate uptake rate, and product formation. The maximum specific CO uptake rate (q(max) = 34.364 mmol/g cell/h), CO inhibition constant (K(I) = 0.601 atm), and maximum rate of ethanol (R(max) = 0.172 mmol/L/h at P(CO) = 0.598 atm) and acetate (R(max) = 0.096 mmol/L/h at P(CO) = 0.539 atm) production were determined from the applied models.

Characterization and evaluation of the novel agarose-nickel composite matrix for possible use in expanded bed adsorption of bio-products.

Agarose-nickel (Ag-Ni) composite matrix was evaluated for its use in expanded bed adsorption (EBA). Bovine serum albumin (BSA) and lysozyme were used as model proteins in batch and column adsorption studies. Accordingly, Reactive Green 19 (RG19) dye-ligand was covalently immobilized onto the support matrix to prepare affinity adsorbent for protein adsorption. Results were then compared with data obtained from Streamline commercial matrix. In batch experiments RG19 derivatives of Ag-Ni (RG19-Ag-Ni) exhibited high adsorption rate; and also a higher binding capacity of BSA (31.4mg/ml adsorbent) was observed for Ag-Ni compared to the commercial adsorbent. More than 70% of the adsorption capacity was achieved within 30min which is a reasonable contact time for EBA operations. The equilibrium adsorption data well agreed with Langmuir isotherm model. The expanded bed adsorption studies showed a reasonable breakthrough behavior at high flow rates and a higher dynamic binding capacity (DBC) was obtained for novel matrix in compare to streamline at the same fluid velocity. DBC at 10% breakthrough reached 66% of the saturated adsorption capacity at the high flow velocity of 450cm/h which indicates the favorable column efficiency. Additionally, two different Ag-Ni size fractions (75-150 and 150-300µm) were examined to investigate the expanded bed performance dependency on the adsorbent particle size with respect to the hydrodynamic stability and adsorption properties using lysozyme as model protein. Interestingly, the small ones showed less axial dispersion coefficient (<1.0×10(-5)m(2)/s) which resulted in higher bed stability in high fluid viscosities. Overall, the adsorption experiments results demonstrated that small size fraction of Ag-Ni matrices acts more effectively for expanded bed adsorption of bio-molecules.

Biohydrogen production from CO-rich syngas via a locally isolated Rhodopseudomonas palustris PT.

Biohydrogen production through water­gas shift (WGS) reaction by a biocatalyst was conducted in batch fermentation. The isolated photosynthetic bacterium Rhodopseudomonas palustris PT was able to utilize carbon monoxide and simultaneously produce hydrogen. Light exposure was provided as an indispensable requirement for the first stage of bacterial growth, but throughout the hydrogen production stage, the energy requirement was met through the WGS reaction. At ambient pressure and temperature, the effect of various sodium acetate concentrations in presence of CO-rich syngas on cell growth, carbon monoxide consumption, and biohydrogen production was also investigated. Maximal efficiency of hydrogen production in response to carbon monoxide consumption was recorded at 86 % and the highest concentration of hydrogen at 33.5 mmol/l was achieved with sodium acetate concentration of 1.5 g/l. The obtained results proved that the local isolate; R. palustris PT, was able to utilize CO-rich syngas and generate biohydrogen via WGS reaction.

Determination of optimum conditions for dairy wastewater treatment in UAASB reactor for removal of nutrients.

In this study, the granular sludge was generated for simultaneous nitrification, denitrification and phosphorus removal (SNDPR) and studied on a laboratory scale. Analyzing the nutrients removal percentages from wastewater were scrutinized by using an optimization of the variables, i.e., COD:N:P ratio, OLR, aeration time, MLSS, F:M and HRT. These 6 interrelated parameters were evaluated as the process response. Microscopic observations of the performance of the SNDPR process revealed that the granules included Bacillus sp. in the bacterial community. According to these results, the UAASB system produced an effluent that lends dairy wastewater suitable for land irrigation and that this an attractive process of using granular sludge is appropriate for achieving carbon, nitrogen and phosphorus removal from nutrient-rich wastewater by a biological method.

Biofiltration of ethyl acetate by Pseudomonas putida immobilized on walnut shell.

A biofilter packed with walnut shells was used to eliminate ethyl acetate from an air stream. The shells treated with NaOH were used as medium for immobilization of Pseudomonas putida PTCC 1694. At an empty bed residence time (EBRT) of 60s, a removal efficiency of 99% was achieved at inlet concentrations lower than 430ppm of ethyl acetate. The removal efficiency decreased below 80% with an increase in inlet concentration of ethyl acetate. When the EBRT was increased to 75 s, the removal efficiency remained above 80% even though the inlet loading rate was increased to 421g/m(3)h. Michaelis-Menten type and zero-order diffusion limited models were employed and the predicted data perfectly matched the experimental data. Thus P. putida immobilized on walnut shell has potential for the removal of ethyl acetate from air streams.