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Publications (114)
Plastics are now indispensable in our daily lives. However, the pollution from plastics is also increasingly becoming a serious environmental issue. Recent years have seen more
sustainable approaches and technologies, commonly known as upcycling, to transform
plastics into value-added materials and chemical feedstocks. In this review, the latest re...
The decline of fossil fuel reserves and the problems of climate change due to emission of greenhouse gases necessitates the need for alternative sustainable green biofuels. Biodiesel is one such green biofuel which is a mixtures of mono-alkyl esters. In the present study, fatty acid ethyl esters were synthesized from dry microalgae in supercritical...
Recently perovskite materials have received extensive attention for dry reforming of methane (DRM) reaction due to their stable ordered crystalline structure. In this work, materials with ionic substitutions of Ru, Pt, and Pd in LaAlO3 perovskite were synthesized using solution combustion synthesis route. The characterizations of catalysts were car...
Due to the limited access to safe drinking water, there is an emerging need to have a quick water decontamination strategy wherein all the major contaminants of water like dyes, organic compounds, and pathogenic bacteria can be removed using a sustainable approach. Herein, we introduce a facile method to strongly couple photocatalytic dual active A...
Photoelectrochemical cells have been used as one of the most common artificial photosynthetic approaches to mimic natural photosynthetic water splitting reactions. However, despite the tremendous advances made to improve the affordability and efficiency of photoelectrochemical water splitting, it is still not an economically feasible method to prod...
Unique optical properties render the semiconductor Nb2O5 nanoparticles suitable for light harvesting and photocatalytic applications. This study focuses on determining the optical properties such as band gap, conduction band edge,...
Photoelectrocatalytic mechanism of ZnO/CuI for antibiotic resistant bacterial disinfection.
In the present work, Z-scheme composite C3N4/CuWO4 was synthesised by sol-gel method for the photocatalytic degradation of a mixed population of Gram-positive bacteria (S. aureus) and Gram-negative bacteria (E. coli). The effect of the photoinactivation was observed for two different types of bacteria in the same medium together and individually in...
Interfacial coupling of semiconductor with metal has been demonstrated for inactivation of E. coli. Fe doped ZnO was synthesized by sol–gel method that resulted in enhanced absorbance in visible region. Various concentrations of Cu were impregnated on Fe doped ZnO that eventually turned into copper oxide and the photocatalytic activity of this mate...
Fatty acid methyl esters (FAMEs) are useful as biodiesel and have environmental benefits compared to conventional diesel. In this study, these esters were synthesized non-catalytically from non-edible vegetable oils: neem oil and mahua oil with two different methylating agents: methanol and methyl tert-butyl ether (MTBE). The effects of temperature...
A novel ternary hybrid, ZnO-CdS-Ag was synthesized and photocatalytic inactivation of E.coli using UV and visible light irradiation was performed. The morphology of synthesized materials was validated by SEM, whereas the crystal details were evaluated by XRD and TEM. Diffuse reflectance was measured to determine the band gap and analyse the absorpt...
The solubilities of two lipid derivatives, geranyl butyrate and 10-undecen-1-ol, in SCCO2 (supercritical carbon dioxide) were measured at different operating conditions of temperature (308.15 to 333.15 K) and pressure (10 to18 MPa). The solubilities (in mole fraction) ranged from 2.1x10-3 to 23.2x10-3 for geranyl butyrate and 2.2x10-3 to 25.0x10-3...
Co-doping of a transition metal ion (Cu) and non-metal ion (N) on metal oxide substrate ZnO was achieved for the first time. The transition metal doping and N doping was carried out using combustion synthesis and a hydrothermal method, respectively. The combined effect of Cu and N doping was observed by varying the Cu percentage and keeping the nit...
The cybernetic modeling framework provides an interesting approach to model the regulatory phenomena occurring in microorganisms. In the present work, we adopt a constraints based approach to analyze the nonlinear behavior of the extended equations of the cybernetic model. We first show that the cybernetic model exhibits linear growth behavior unde...
The cybernetic modeling framework for the growth of microorganisms provides for an elegant methodology to account for the unknown regulatory phenomena through the use of cybernetic variables for enzyme induction and activity. In this paper, we revisit the assumption of limited resources for enzyme induction (∑ui=1) used in the cybernetic modeling f...
Understanding the growth behavior of microorganisms using modeling and optimization techniques is an active area of research in the fields of Biochemical Engineering and Systems Biology. In this paper, we propose a general modeling framework, based on Monod model, to model the growth of microorganisms. Utilizing the general framework, we formulate...
Microorganisms exhibit varied regulatory strategies such as direct regulation, symmetric anticipatory regulation, asymmetric anticipatory regulation etc. Current mathematical modeling frameworks for the growth of microorganisms either do not incorporate regulation or assume that the microorganisms utilize the direct regulation strategy. In the pres...
The photocatalytic inactivation of Escherichia coli was studied with combustion synthesized TiO2 photocatalysts in the presence of visible light. A series of 400 W lamps irradiating in the visible region of the solar spectrum was used. The effect of various parameters, such as catalyst loading, light intensity, presence of inorganic ions, addition...
The photocatalytic antibacterial activity of Ag impregnated combustion synthesized TiO2 (0.25 g/L) was studied against Escherichia coli in presence of UV irradiation. The effect of various parameters, such as anions, cations, hydrogen peroxide and pH, on the photocatalytic inactivation was investigated. The addition of inorganic ions showed a negat...
Stirred tank bioreactors, employed in the production of a variety of biologically active chemicals, are often operated in batch, fed-batch, and continuous modes of operation. The optimal design of bioreactor is dependent on the kinetics of the biological process, as well as the performance criteria (yield, productivity, etc.) under consideration. I...
Degradation of dimethoate under UV irradiation using TiO(2)/polymer films prepared by the layer-by-layer (LbL) method was investigated. The thin films were fabricated on glass slides and the surface morphology and roughness of the thin films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force micros...
Photocatalysis using semiconductor catalyst such as TiO2, in presence of UV light, is a promising technique for the inactivation of various microorganisms present in water. In the current study, the photocatalytic inactivation of Escherichia coli bacteria was studied with commercial Degussa Aeroxide TiO2 P25 (Aeroxide) and combustion synthesized Ti...
The photocatalytic inactivation of Escherischia coli and Pichia Pastoris was studied with combustion synthesized titanium dioxide photocatalysts. Three different combustion synthesized (CS) catalysts were used viz., CS–TiO2, 1% Ag substituted in TiO2 and 1% Ag impregnated in TiO2. All the combustion synthesized catalysts showed higher activity as c...
Interpenetrating polymer networks (IPNs) comprising weakly acidic and weakly basic cross-linked polymers, namely, poly(acrylic acid-co-ethyleneglycol dimethacrylate) (XPAA) and 80% ethoxylated polyethyleneimine (EPEI) cross-linked with glutaraldehyde, were prepared by the copolymerization of acrylic acid (AA) and ethyleneglycol dimethacrylate by a...
Fabrication of multilayer ultrathin composite films composed of nanosized titanium dioxide particles (P25, Degussa) and polyelectrolytes (PELs), such as poly(allyl amine hydrochloride) (PAH) and poly(styrene sulfonate sodium salt) (PSS), on glass substrates using the layer-by-layer (LbL) assembly technique and its potential application for the phot...
Ferrous iron bio-oxidation by Acidithiobacillus ferrooxidans immobilized on polyurethane foam was investigated. Cells were immobilized on foams by placing them in a growth environment and fully bacterially activated polyurethane foams (BAPUFs) were prepared by serial subculturing in batches with partially bacterially activated foam (pBAPUFs). The d...
Crosslinked poly(acrylic acid) (XPAA) made by copolymerization of acrylic acid and ethylene glycol dimethacrylate in bulk was further reacted with 80% ethoxylated polyethyleneimine, and the latter insolubilized by treatment with glutaraldehyde. The resulting composite sorbent, XPAA(EPEI.XG), containing carboxylic acid groups and weakly basic tertia...
Biomethanation of herbaceous biomass feedstock has the potential to provide clean energy source for cooking and other activities in areas where such biomass availability predominates. A biomethanation concept that involves fermentation of biomass residues in three steps, occurring in three zones of the fermentor is described. This approach while at...
In India, engineering is one of the preferred choices for good students ready to undertake the undergraduate education after 12 years high school/junior college education. Rapid economic growth (8-9%) in past several years has fuelled a demand for engineering graduates. The enrolment of undergraduates in chemical engineering in India has steadily i...
The objective of this work was to analyse the scientometric parameters for chemical engineering publications. We have compared the number of journal publications and citations by various countries and institutions. The publication record in terms of quantitative aspects of the number of publications from China has increased exponentially over the l...
Applicability of Ohshima's soft-particle model to evaluate the surface potential of Acidithiobacillus ferrooxidans cells is discussed here. The electrokinetic properties were examined by electrophoretic mobility measurements and analyzed using the soft particle electrophoresis theory. As the ionic concentration increased, the mobility of the bacter...
A new methodology based on a metabolic control analysis (MCA) approach is developed for the optimization of continuous cascade bioreactor system. A general framework for representation of a cascade bioreactor system consisting of a large number of reactors as a single network is proposed. The kinetic and transport processes occurring in the system...
Natural fibers are increasingly being used as reinforcement in commercial thermoplastics due to their low cost, high specific properties and renewable nature. While the maleic anhydride modified polypropylene (MAPP) is most commonly used as compatibilizer to improve interfacial adhesion between hydrophilic wood–fibers and hydrophobic polypropylene,...
The optimal design of a multiproduct batch chemical plant is formulated as a multiobjective optimization problem, and the resulting constrained mixed-integer nonlinear program (MINLP) is solved by the nondominated sorting genetic algorithm approach (NSGA-II). By putting bounds on the objective function values, the constrained MINLP problem can be s...
A commercial acrylic fiber with 92% (w/w) acrylonitrile content was partially hydrolyzed converting a fraction of the nitrile (CN) groups to carboxylic acid (COOH) groups, to coat the fiber with polyethylenimine (PEI) resin, which was then crosslinked with glutaraldehyde and further quaternized with ethyl chloroacetate to produce a novel strong-bas...
In this work the effect of organic reducing reagents, namely, ascorbic acid, oxalic acid and L-cysteine on dissolution of commercial TiO(2) has been investigated. Kinetic studies showed that a maximum of about 45% of TiO(2) was dissolved by ascorbic acid in 4h when oxide:acid molar ratio was kept at 1:2. The dissolution of TiO(2) increased with inc...
Ferromanganese ocean nodules contain important transition metals like Cu, Co and Ni. They serve as an alternate source of these metals especially in countries like India, which does not have land-based resources of Co and Ni. The existing methods for metal dissolution from the nodules use highly acidic or alkaline media accompanied by strong organi...
The esterification of fatty acids of different chain lengths with isoamyl alcohol was studied in solvent free conditions and in supercritical carbon dioxide (SCCO2). Three different commercial lipases, Hog pancreas lipase (HPL), Lipolase 100T, and Novozym 435 were used for the synthesis of the esters. The results indicate that Novozym gave high con...
Many optimal control problems are characterized by their multiple performance measures that are often noncommensurable and competing with each other. The presence of multiple objectives in a problem usually give rise to a set of optimal solutions, largely known as Pareto-optimal solutions. Evolutionary algorithms have been recognized to be well sui...
Polymetallic ocean nodules offer an alternative source for extracting valuable strategic metals like Cu, Co and Ni. A novel biodissolution process was carried out, employing the cell-free spent growth medium from a marine organism (Bacillus M1) isolated from nodules; and Cu, Co and Ni solubilization from the nodules was observed to be beyond the th...
Octyl palmitate was enzymatically synthesized from palmitic acid and octanol. The synthesis of octyl palmitate was investigated in three supercritical fluids, namely, carbon dioxide, methane, and ethane, using three different enzymes. The effects of temperature, initial water content, alcohol concentration, and enzyme loading on the conversion were...
When using a genetic algorithm (GA) to solve optimal control problems that can arise in a fed-batch bioreactor, the most obvious direct approach is to rely on a finite dimensional discretization of the optimal control problem into a nonlinear programming problem. Usually only the control function is discretized, and the continuous control function...
Anaerobic digestion of animal waste in biogas plants for energy, manure and sanitation has made a significant impact in quality of rural life wherever it has been deployed. Insufficiency of animal dung resources limits the use of this technology to only an eighth of the overall Indian rural population. Yet the convenience of a biogas plant in rural...
Selective separation of pyrite from other associated ferrous sulphides at acidic and neutral pH has been a challenging problem. This paper discusses the utility of Acidithiobacillus ferrooxidans for the selective flotation of chalcopyrite from pyrite. Consequent to interaction with bacterial cells, pyrite remained depressed even in the presence of...
A commercial acrylic fiber containing 92 wt % acrylonitrile was hydrolyzed to convert a part of its nitrile (CN) groups to carboxylic acid (COOH) groups and then was coated chemically with 80% ethoxylated polyethylenimine (EPEI) resin, followed by crosslinking with glutaraldehyde. The resulting sorbent, PAN(CO2H)(EPEI.XG), containing carboxylic aci...
Polymetallic Indian Ocean nodules offer a lucrative resource for valuable strategic metals like Cu, Co and Ni. A novel bioleaching process to recover those metals from the nodules at near-neutral pH and ambient temperature is presented in this paper. The significant role of in situ microorganisms and their by-products in solubilization of valuable...
The determination of optimal feed rate profiles for fed-batch bioreactors with more than one feed rates is a numerically difficult problem involving multiple singular control variables. A solution strategy based on genetic algorithm approach for the determination of optimal substrate feeding policies for fed-batch bioreactors with multi-control var...
Polymetallic Indian Ocean nodules offer a lucrative resource for valuable strategic metals such as Cu, Co and Ni. A novel bioleaching process using cell-free spent growth medium from a fully-grown culture of a marine organism isolated from the nodules (Bacillus M1) dissolved about 45% Co, and 25% Cu and Ni at a the pH of 8.2 in 4 h. To enhance meta...
This article reviews the state of the art in processing and extracting ocean manganese nodules. It briefly reviews the mining sites where abundant rich nodules occur and also describes the metal distribution in nodules. The physicochemical characteristics of the nodules, touching upon different facets such as mineralogy, geochemistry, moisture cont...
A fabric made of 100% acrylic fiber "Cashmilon" has been partially hydrolyzed to convert a fraction of its nitrile (-CN) groups to carboxylic acid (-COOH) groups and then gel-coated with 80% ethoxylated polyerhyleneimine (EPEI) resin and cross-linked with glutaraldehyde to produce a novel sorbent in fabric form, containing weakly acidic and weakly...
The esterification of palmitic acid with ethanol was investigated at various temperatures (35- 70 °C) in the presence of three lipases (Novozym 435, Lipolase 100T, and hog pancreas lipase) in supercritical carbon dioxide $(SCCO_2)$ and under solvent-free conditions. All enzymes showed an optimum temperature of 55 °C under both conditions. The effec...
The determination of optimal feed rate profiles for fed-batch bioreactors with two feed rates is a numerically difficult problem involving two singular control variables. A solution strategy based on genetic algorithm approach for the determination of optimal substrate feeding policies for fed-batch bioreactors with two control variables is propose...
A marine organism ( Bacillus M1) isolated from Indian Ocean manganese nodules was characterized. The organism grew well in artificial seawater medium, at near neutral pH, 30 degrees C and 0.25 M NaCl, and showed MnO(2)-reducing activity. Growing cultures of Bacillus M1 as well as cell-free spent liquor from fully-grown cultures were employed to ext...
The esterification of myristic acid with ethanol was studied with a commercial lipase (crude Hog pancreas lipase, HPL). The reaction was investigated in solvent-free conditions and in two solvents: supercritical carbon dioxide (SCCO2) and acetonitrile. Conversions of up to 76% were obtained under solvent-free conditions while conversions of only up...
A thermodynamic model was developed for modeling the solubilities of fatty acids in supercritical carbon dioxide. The model combines the Peng–Robinson equation of state (EOS) with the two parameter van der Waal’s mixing rules. The model is applied to predict the solubilities of various fatty acids. The two adjustable interaction parameters in the m...
The results of modeling the biooxidation of a mixed sulfidic concentrate by Thiobacillus ferrooxidans is reported here. A kinetic model, which accounts for the dissolution of sulfide matrix due to both bacterial attachment onto the mineral surface and indirect leaching, has been proposed. A comprehensive system approach is employed for modeling the...
Indian Ocean manganese nodules offer a lucrative resource for valuable strategic metals like Cu, Co and Ni. A novel bio-leaching process to recover these metals in presence of organic reductants from the nodules at near neutral pH and ambient temperature is presented in this paper. The cell-free growth supernatant of a marine microorganism isolated...
This paper introduces a numerical technique for solving nonlinear optimal control problems. The universal function approximation capability of a three-layer feedforward neural network has been combined with a simulated annealing algorithm to develop a simple yet efficient hybrid optimisation algorithm to determine optimal control profiles. The appl...
An optimisation procedure based on genetic algorithm approach is developed for the determination of substrate feed profiles for the optimal operation of fed-batch bioreactors. The problem specific knowledge generated through the rigorous application of the optimal control theory is used to formulate the set of decision variables representing the qu...
A novel vinyl monomer with an isocyanate functional group, m-isopropenyl-alpha,alpha-dimethylbenzyl-isocyanate (m-TMI), was grafted onto isotactic polypropylene (i-PP) using dicumyl peroxide (DCP) as the initiator. This would open up the possibility of using the grafted polymer with the reactive isocyanate group as compatibilizer for blending carbo...
Metabolic control analysis (MCA) of pyruvate dehydrogenase multienzyme (PDH) complex of eucaryotic cells has been carried out using both in vitro and in vivo mechanistic models. Flux control coefficients (FCC) for the sensitivity of pyruvate decarboxylation rate to activities of various PDH complex reactions are determined. FCCs are shown to be str...
Pyruvate conversion to acetyl-CoA by the pyruvate dehydrogenase (PDH) multienzyme complex is known as a key node in affecting the metabolic fluxes of animal cell culture. However, its possible role in causing possible nonlinear dynamic behavior such as oscillations and multiplicity of animal cells has received little attention. In this work, the ki...
Strategies for efficient start-up of a continuous process for biooxidation of refractory gold ore and concentrate obtained from Hutti Gold Mines Limited (HGML), India are discussed in this work. The biooxidation of the concentrate at high pulp density (10%) with wild strain of Thiobacillus ferrooxidans isolated from HGML mines is characterized by s...
Commercially important flavor esters of isoamyl alcohol, catalyzed by crude hog pancreas lipase (HPL), were synthesized under solvent-free conditions and in supercritical carbon dioxide. The esters synthesized were isoamyl acetate, isoamyl propionate, isoamyl butyrate, and isoamyl octanoate. Very low yields (3-4%) of isoamyl acetate were obtained,...
A mathematical model is proposed to analyze the mass transfer limitations in phenol biodegradation using Pseudomonas putida immobilized in calcium alginate. The model takes into account internal and external mass transfer limitations, substrate inhibition kinetics and the dependence of the effective diffusivity of phenol in alginate gel on cell con...
A systematic analysis of the problem of determining optimal feeding strategies for immobilized enzyme reactions in fed batch bioreactor is presented in this paper. The optimal control theory is applied to a heterogeneous bioreactor model consisting of a bulk liquid phase and an immobilized enzyme phase. The optimal feeding policy and singular inter...
This paper describes some of the important microbiological and engineering challenges in scaling up biobeneficiation of bauxite. A soil bacterium Paenibacillus polymyxa was recently shown to selectively remove calcium and iron impurities from low grade bauxite (< 50% Al), for abrasive and refractory applications. respectively. An industrial scale f...
A waste fungal biomass containing killed cells of Aspergillus niger was efficiently used in the removal of toxic metal ions such as nickel, calcium, iron and chromium from aqueous solutions. The role of different parameters such as initial metal ion concentration, solution pH and biomass concentration on biosorption capacity was established. The ma...
A bacterium Bacillus polymyxa was found to be capable of selective removal of calcium and iron from bauxite. The bioleached residue was found to be enriched in its alumina content with insignificant amounts of iron and calcium as impurities. The developed bio- process was found to be capable of producing a bauxite product which meets the specifica-...
The biological removal of calcium SI-om a bauxite ore in the presence of the soil bacterium Paenibacillus polymyxa is demonstrated. A column bioreactor that call be either-operated in a fluidized-bed (FB) mode for coarser particles or in a total-recycle-slurry (TRS) mode for finer particles was designed fabricated and rested for this purpose. For t...
The decomposition and gas production pattern of eight unprocessed biomass feedstocks representing annual weeds, leaf litter, agro residues and market wastes were monitored in this laboratory study. Solid phase fermentation was effected with a weekly fed biomass bed sprinkled twice daily with recycled fermentor liquid to initiate and sustain biogas...
A comparative study of the kinetics of lead and zinc biosorption was carried out using the biomass of Streptoverticillium cinnamoneum, Penicillium chrysogenum and Citrobacter sp. The uptake of metals in all cases was found to be rapid in the first 10 min, reaching an equilibrium within 30 min of contact. The rate of metal uptake was independent of...
Electrobioleaching of a sphalerite flotation concentrate at a positive DC potential of +0.4V (SCE) has been discussed and compared with that at −0.5V(SCE). Probable mechanisms in the electrobioleaching process are considered with respect to oxidative and reductive dissolution as well as to direct and indirect roles of Thiobacillus ferrooxidans. The...
An algorithm using feedforward neural network model for determining optimal substrate feeding policies for fed-batch fermentation process is presented in this work. The algorithm involves developing the neural network model of the process using the sampled data. The trained neural network model in turn is used for optimization purposes. The advanta...
A strain of Thiobacillus ferrooxidans was adapted to grow at higher concentrations of copper by single step culturing in the presence of 20 g/L (0.314 mol/L) cupric ions added to 9K medium. Exposure to copper results in change in the surface chemistry of the microorganism. The isoelectric point of the adapted strain (pI = 4.7) was observed to be at...
The utility of a waste, dead fungal biomass in the removal of various metal ions such as calcium, iron, nickel and chromium when present individually and in possible combinations has been demonstrated. Although the tests were carried out using synthetic solutions of varying pH and metal ion concentrations, the results are representative of typical...
Biomass feedstocks, such as leaf litter, weeds and agroresidues, have been considered as alternative feedstocks to meet rural energy needs in India. Six different types of biomass substrates representing commonly available fresh and dry feedstocks were studied for their decomposition pattern and methanogenic activities in order to arrive at optimum...
The influence of different concentrations of base metal ions, such as Cu2+, Zn2+ and Fe3+, when present either alone or in different possible binary and ternary combinations in a 9K medium, on the ferrous ion oxidation ability of Thiobacillus ferrooxidans was studied. Levels and degree of toxicity of these ions have been quantified in terms of toxi...
A mathematical model describing the dynamics of mammalian cell growth in hollow fibre bioreactor operated in closed shell mode is developed. Mammalian cells are assumed to grow as an expanding biofilm in the extra-capillary space surrounding the fibre. Diffusion is assumed to be the dominant process in the radial direction while axial convection do...
A microbial survey of Jamnagar bauxite mines in Gujarat, India, revealed the indigenous presence of a variety of autotrophic and heterotrophic bacteria and fungi associated with the ore body and water ponds in the vicinity. Among these, bacteria belonging to the genera Thiobacillus, Bacillus and Pseudomonas are implicated in the weathering of alumi...
We seek efficient techniques to evaluate the performance of multistation production systems with limited interstation buffers and station breakdown. Our ultimate objective is to develop a practical computer implementation that can be used for analysis and design. Practically implies two design considerations: flexibility and computational efficienc...
Calcium and iron removal from a bauxite ore by Bacillus polymyxa has been demonstrated. Within a period of 7 days, the above organism could remove all the calcium and about 45% of iron from the ore in the presence of 2% sucrose in a Bromfield medium. The highest removal of calcium and iron corresponded with the maximum in extracellular polysacchari...
Enumeration of adhered cells of Thiobacillus ferrooxidans on sulphide minerals through protein assay poses problems due to interference from dissolved mineral constituents. The manner in which sulphide minerals such as pyrite, chalcopyrite, sphalerite, arsenopyrite and pyrrhotite interfere with bacterial protein estimation is demonstrated. Such int...
An isolate of Thiobacillus ferrooxidans derived from gold mine water samples was repeatedly subcultured at increasing temperatures (from 30° to 42°C) in 9K medium. The temperature-adapted strain was found to be more efficient in the bioleaching of pyrite mineral than the wild type. When temperature-tolerant strains were cultured repeatedly in 9K me...
Nonliving waste biomass consisting of Aspergillus niger attached to wheat bran was used as a biosorbent for the removal of copper and zinc from aqueous solutions. Copper and zinc uptake by the biomass obeyed Langmuir isotherms. The binding capacity of the biomass for copper was found to be higher than that for zinc. The metal uptake, expressed in m...
An adaptive optimization algorithm using backpropogation neural network model for dynamic identification is developed. The algorithm is applied to maximize the cellular productivity of a continuous culture of baker's yeast. The robustness of the algorithm is demonstrated in determining and maintaining the optimal dilution rate of the continuous bio...
A review of published literature on the biosorption of metals using nonliving biomass is presented. Factors such as pH, temperature, initial metal concentration, biomass loading, the presence of co-ions and the pretreatment of biomass influence the metal uptake by biomass. Although few generalizations are possible, unified theories regarding the me...
A mathematical model is developed to simulate oxygen consumption, heat generation and cell growth in solid state fermentation
(SSF). The fungal growth on the solid substrate particles results in the increase of the cell film thickness around the particles.
The model incorporates this increase in the biofilm size which leads to decrease in the poros...
Shake flask experiments on the leaching of particles of pyrite mineral with Thiobacillus ferrooxidans indicate that, under conditions of large particle sizes and high pulp density, the dissolution occurs primarily through direct attachment of the micro-organism on the mineral surface. Even though both Fe2+ and the cells are present in the aqueous p...
A mathematical model for glucose and oxygen consumption, and cell growth during fungal growth on a single solid particle is developed. A moving biofilm is assumed to be present on the surface of the solid particle. Initially only glucose is assumed to be growth limiting and later oxygen transferred from the gas phase on to the biofilm is also assum...
Affinity chromatography (biospecific adsorption) relies on specific interactions of biological molecules such as enzymes, antigens, antibodies, and proteins. The process consists of three steps: adsorption, washing, and elution. A mathematical model including convection, diffusion, and reversible reaction is formulated to analyse the breakthrough b...
The ability of various fungal species isolated from gold mines to uptake gold and base metals such as zinc, copper, iron and lead from gold-process cyanide effluents was investigated. Under identical treatment conditions, different strains showed wide variations in their ability to take up gold and other base metals. Aspergillus terreus exhibited a...
The optimization problem for fed-batch fermentation is formulated in a framework which allows comparison of optimal operating policies with four different control variables. These variables include the original control variable, namely the substrate feed rate, and three transformed control variables, i.e. the substrate concentration in the fermente...
