Batch Kinetic Model Research Articles

Denitrification Kinetics of Nitrate by a Heterotrophic Culture in Batch and Fixed-Biofilm Reactors

Herein, the progress of nitrate removal by a heterotrophic culture in a batch reactor and continuous-flow fixed-biofilm reactor was examined. Two batch experiments for nitrate reduction with acetate degradation using 250 mL batch reactors with acclimated denitrifying biomass were conducted. The experimental results indicated that the nitrate was completely reduced; however, the acetate remained at a concentration of 280 mg/L from initial nitrate concentration of 100 mg/L. However, the acetate was fully biodegraded by the denitrifying biomass at an initial nitrate concentration of 300 mg/L. To evaluate the biokinetic parameters, the concentration data of nitrate, nitrite, acetate, and denitrifying biomass from the batch kinetic experiments were compared with those of the batch kinetic model system. A continuous-flow fixed-biofilm reactor was used to verify the kinetic biofilm model. The removal efficiency of nitrate in the fixed-biofilm reactor at the steady state was 98.4% accompanied with 90.5% acetate consumption. The experimental results agreed satisfactorily with the model predictions. The modeling and experimental approaches used in this study could be applied in the design of a pilot-scale, or full-scale, fixed-biofilm reactor for nitrate removal in water and wastewater treatment plants.

Preparation and performance of alginate/basil seed mucilage biocomposite for removal of eriochrome black T dye from aqueous solution

Mucilage extracted from Basil seeds were captured in calcium alginate biobeads. The beads were tested as eco-friendly adsorbents to eriochrome black T dye from aqueous solution. The synthesized biocomposite was characterized by FESEM, EDX, TGA, and FTIR techniques. Batch and continuous experiments were performed for dye adsorption studies using the synthesized biocomposite. The effect of contact time, pH, initial concentration of dye, and amount of adsorbent on dye adsorption capacity, and also kinetics, isotherm, thermodynamics, regeneration, and swelling investigations were performed. The results showed that the adsorption of eriochrome black T follows the pseudo-second-order batch kinetic model, Yoon–Nelson and Thomas dynamic models, and Freundlich isotherm model. The thermodynamic results showed that the dye adsorption process with the synthetic adsorbent is an exothermic spontaneous process.

Treatment of arsenic (III) contaminated water by dynamically modified iron-coated sand (DMICS)

In this paper, dynamically modified iron-coated sand (DMICS) was synthesized by dynamic soaking of iron onto the sand. The DMICS was tested for As(III) removal from the aqueous solution by adsorption studies. The effects of particle size, initial arsenic concentration and adsorbent dose on arsenic removal efficiencies were evaluated by batch kinetic studies. Two batch kinetic models i.e. chemical reaction rate and pseudo-second order have been applied to see the behaviour of As(III) adsorption over DMICS. Langmuir, Freundlich and Temkin isotherms were used to describe the equilibrium studies data. Langmuir isotherm was found better fit when compared with other isotherms based on coefficient of correlation (R2) values. The maximum adsorption capacity of DMICS was calculated as 0.29 mg/g as per Langmuir isotherm. The adsorption process was pH-dependent and maximum arsenic removal occurred in the pH range of 6–8. Scanning electron microscope was conducted on arsenic-loaded sand whereas, X-ray diffractogram (XRD) analysis was conducted on plain sand, DMICS and arsenic-loaded DMICS. XRD spectra supported the presence of arsenic on the surfaces of DMICS. The breakthrough and exhaustion times for 60 cm media column were 114 h and 200 h, respectively, based on column studies data. The DMICS has shown a good potential for arsenic remediation from aqueous medium.

Effect of MW and pH on poly(ethylene glycol) adsorption onto carbon

Poly(ethylene glycol) (PEG) is a water-soluble polymer commonly found in industrial and domestic wastewaters. In this study the adsorption onto granular activated carbon (GAC) of PEG, of different molecular weights, from aqueous solutions was examined to evaluate its applicability to wastewater treatment. Batch kinetic models have been tested to predict the rate constant of adsorption. The amount of PEG adsorbed on activated carbon depends mainly on the pH, the MW and on the solution characteristics. The adsorption at fixed temperature decrease by MW (PEG-8000 350 mg/g) at low and high pH values show a great potential for GAC. The adsorption process can be described well with the Langmuir and the pseudo first order equation. The effective intraparticle diffusion coefficients of PEG molecules in the GAC adsorbent varying according to the MW values in the range 8.45 × 10−3–9.71 × 10−7.

Geochemical Study on CO2-rich Waters of Daepyeong Area, Korea: Monitoring Implication for CO2 Geological Storage

Geochemical monitoring was performed on dilute CO2-rich water as a natural analogue study of CO2 geologic storage. Field measurement and sampling for dissolved ions analyses and isotope analysis were carried out from July of 2009 to November of 2010. Spring and groundwater samples were classified into diluted CO2-rich water (average pH=4.6, EC=151 S/cm), concentrated CO2-rich water (average pH=6.1, EC=1,301), and ordinary groundwater (average pH=6.6, EC=201). pH, EC and dissolved major ions were not changed noticeably during monitoring period which indicates that reservoir of CO2-rich water was not affected by changes of surface condition and recharged groundwater. pH and EC of diluted CO2-rich water from this study area is lowest value among the CO2-rich waters from South Korea. On the other hand, concentrated CO2-rich water was also observed in 5 km north of diluted CO2 - rich water of Daepyeong area. Carbon isotope ratio (δ13 C) of concentrated CO2-rich water is -7.4% and average δ13 C of diluted CO2 rich water is -7.2% which indicates that the CO2 source of concentrated and diluted CO2-rich water could be closely related. The result of simple mixing model revealed that low pH and high TDIC (Total Dissolved Inorganic Carbon) concentration of diluted CO2-rich water was not explained by simple mixing between groundwater and concentrated CO2-rich water. Therefore, inflow of excess CO2 and/or secondary accumulated CO2 should be applied CO2-rich water system in Daepyeong area and reacted with host rock. A batch kinetic model was applied for simulating the ion concentration, pH and TDIC of diluted CO2-rich water after reacting with groundwater, rock and high CO2 condition (50.2 mmol/L). As a result of batch kinetic model, Na+ and K+ concentration of DPw-4 sample was reached in about 20 years. Conclusively, low EC, dissolved ions and high TDIC contents of dilute CO2-rich water indicate that water-rock interaction has been took place in short period of time after input of CO2. The result of this study implies that shallow groundwater quality except pH could not change significantly in the early stage of leakage of CO2. The water-rock reaction rate might not be fast enough in surface environment.

Combination effect of pH and acetate on enzymatic cellulose hydrolysis

The productivity and efficiency of cellulase are significant in cellulose hydrolysis. With the accumulation of volatile fatty acids (VFAs), the pH value in anaerobic digestion system is reduced. Therefore, this study will find out how the pH and the amount of acetate influence the enzymatic hydrolysis of cellulose. The effects of pH and acetate on cellulase produced from Bacillus coagulans were studied at various pH 5-8, and acetate concentrations (0-60 mmol/L). A batch kinetic model for enzymatic cellulose hydrolysis was constructed from experimental data and performed. The base hypothesis was as follows: the rates of enzymatic cellulose hydrolysis rely on pH and acetate concentration. The results showed that the suitable pH range for cellulase production and cellulose hydrolysis (represents efficiency of cellulase) was 2.6-7.5, and 5.3-8.3, respectively. Moreover, acetate in the culture medium had an effect on cellulase production (K(I) = 49.50 mmol/L, n = 1.7) less than cellulose hydrolysis (K(I) = 37.85 mmol/L, n = 2.0). The results indicated that both the pH of suspension and acidogenic products influence the enzymatic hydrolysis of cellulose in an anaerobic environment. To enhance the cellulose hydrolysis rate, the accumulated acetate concentration should be lower than 25 mmol/L, and pH should be maintained at 7.

Characterization and adsorption of arsenate and selenite onto Kemiron

Kemiron, a commercially available, porous iron oxide sorbent was evaluated in batch systems for arsenate (As(V)) and selenite (Se(IV)) removal from aqueous solutions as a function of pH, ionic strength, and particle size (< 38 μ m and between 250 and 425 μ m). BET surface area of Kemiron is 39.8 m2/g and Electron dispersive spectroscopy (EDS) studies found Kemiron to be 40.37% iron and 42.25% oxygen by mass. Langmuir isotherms best described the As(V) and Se(IV) removal at pH 7 with maximum adsorption capacity of 82 mg/g and 52 mg/g respectively. As(V) and Se(IV) sorption decreased as pH increased and both anions were unaffected by sodium nitrate (NaNO3) background electrolyte. As(V) sorption was not affected in surface water samples from the Hillsborough River. Batch kinetic models of the experimental data on the 250 to 425 μ m particle size yielded mass transfer coefficients of 0.0008 min−1 and 0.009 min−1 for As(V) and Se(IV) respectively.

Biosorptive Removal of Ni(Ii) from Wastewater and Industrial Effluent

The objective of the present work was to investigate the removal of Ni(II) by the fresh biomass (FBM) and chemically treated leached biomass (LBM) of Calotropis procera. The scope of the work included screening of the biosorbents for their metal uptake potential, batch equilibrium, column mode removal studies and kinetic studies at varying pH (2-6), contact time, biosorbent dosages (1-25 g/L) and initial metal ion concentration (5-500 mg/L). The development of batch kinetic model and determination of order, desorption studies, column studies were investigated. It was observed that pH had marked effect on the Ni(II) uptake. Langmuir and Freundlich models were used to correlate equilibrium data on sorption of Ni(II) metallic ion by using both FBM and LBM at 28 degrees C and pH 3 and different coefficients were calculated. It was found that both biomasses were statistically significant fit for Freundlich model. The biomass was successfully used for removal nickel from synthetic and industrial effluents and the technique appears industrially applicable and viable.

Scale-up of batch kinetic models

The scale-up of batch kinetic models was studied by examining the kinetic fitting results of batch esterification reactions completed in 75 mL and 5 L reactors. Different temperatures, amounts of catalysts, and amounts of initial starting reagents were used to completely characterize the reaction. A custom written Matlab toolbox called GUIPRO was used to fit first-principles kinetic models directly to in-line NIR and Raman spectroscopic data. Second-order kinetic models provided calibration-free estimates of kinetic and thermodynamic reaction parameters, time dependent concentration profiles, and pure component spectra of reagents and product. The estimated kinetic and thermodynamic parameters showed good agreement between small-scale and large-scale reactions. The accuracy of pure component spectra estimates was validated by comparison to collected NIR and Raman pure component spectra. The model estimated product concentrations were also validated by comparison to concentrations measured by off-line GC analysis. Based on the good agreement between kinetic and thermodynamic parameters and comparison between actual and estimated concentration and spectral profiles, it was concluded that the scale-up of batch kinetic models was successful.

Adsorption kinetics of herbicide paraquat from aqueous solution onto activated bleaching earth

In the present study, the activated bleaching earth was used as adsorbent for the herbicide paraquat adsorption in a batch adsorber. The rate of adsorption has been investigated under the controlled process parameters like agitation speed, initial paraquat concentration, adsorbent dosage and temperature. A batch kinetic model, based on the assumption of a pseudo-second order mechanism, has been tested to predict the rate constant of adsorption, equilibrium adsorption capacity, time of half-adsorption, and equilibrium concentration by the fittings of the experimental data. The results of the kinetic studies show that the adsorption process can be well described with the pseudo-second order equation. Based on the isotherm data obtained from the fittings of the adsorption kinetics, Freundlich model appears to fit the adsorption better than Langmuir model. In addition, the effective diffusion coefficient has also been estimated based on the restrictive diffusion model.

Adsorption of polyethylene glycol (PEG) from aqueous solution onto hydrophobic zeolite

In the present study, a hydrophobic zeolite was used as an adsorbent for the adsorption of polyethylene glycol (PEG) in water solution and electroplating solution at 25 °C. The adsorption capacities were determined through the adsorption isotherms in a thermostated shaker. The rate of adsorption, on the other hand, was investigated in a batch adsorber under controlled process parameters such as initial PEG concentration (30, 70, 110, 150, 200, and 300 mg dm −3), agitation speed (200, 800, and 1000 rpm), and adsorbent particle size (0.72, 1.44, and 2.03 mm). A batch kinetic model, according to a pseudo-second-order mechanism, has been tested to predict the rate constant of adsorption, equilibrium adsorption capacity, time of half-adsorption, and equilibrium concentration by the fitting of the experimental data. The results of the adsorption isotherm and kinetic studies show that the adsorption process can well be described with the Langmuir and Freundlich models and the pseudo-second-order equation, respectively. Comparing the values of adsorption parameters of PEG in water solution and electroplating solution, there are no significant differences. In addition, the effective diffusion coefficient of the PEG molecule in the microporous adsorbent has been estimated at about 3.20×10 −8 cm 2 s −1 based on the restrictive diffusion model.

The Adsorption of Fluoride Ion from Aqueous Solution by Activated Alumina

The adsorption of fluoride ion in aqueous solution by using alumina was studied in this research. The experimental resultsindicated that the removal efficiency was influenced significantly by solution pH and the optimum operating pH wasfound to be in the range of 5 to 7. For neutral and acidic solutions, the adsorption capacities of fluoride by alumina wasinterfered by the presence of sulfate. The Langmuir and Freundlich isotherms can well describe the equilibrium behaviorsof the adsorption processes. The experimentally determined lowvalues of activation energy indicate nonspecific adsorption isthe predominant mechanism. The surface reaction-limiting batchkinetic model can adequately describe the removal behaviors offluoride ion by alumina adsorption in the batch system.

A comparative study of the mass transfer kinetics of metal biosorption by microbial biomass

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 initial metal concentration. The metal concentration profiles could be well predicted using a batch kinetic model.

Kinetic model of growth and lactic acid production from lactose by Lactobacillus bulgaricus

Batch and continuous fermentation kinetics of Lactobacillus bulgaricas were examined in detail. The batch kinetic model includes the effect of pH, lactate and substrate. The effect of pH on the enzyme β-galactosidase is reflected in the value of μ max, the Monod's growth constant. Empirical expressions to estimate model parameters based on pH were established. These were further used to estimate the cell mass and lactic acid concentration for the fermentation proceeded with no pH control. At high pH lactic acid was mostly formed by growth associated mechanisms and at low pH it was due to the cell maintenance. The relationship between ATP concentration and cell mass in a batch fermentation could be approximated by a Leudeking—Piret like relationship. The continuous fermentation was studied with varying pH and initial substrate conditions. A maximum productivity of 6·2 g/litre per hour was obtained at pH 5·6 for the CSTR system, which was three times the productivity obtained for a batch system at the same pH. The CSTR system had a high productivity over a very small range of retention times. Three stages were found to be sufficient to utilize completely the lactose, but at the cost of decreasing the productivity to 4·8 g/litre per hour.

Mathematically modeling the removal of heavy metals from a wastewater using immobilized biomass

A technique developed by the US Bureau of Mines using biomass, sphagnum peat moss, immobilized in porous polysulfone beads selectively removed Zn, Cd, and other metals from a zinc mining wastewater to concentrations well below the National Drinking Water Standards. The objective of this paper was to obtain experimental data on the biosorption of several heavy metals onto the beads containing sphagnum peat moss and to develop the appropriate mathematical models that might be used to describe the multicomponent phenomena. Nonequilibrium multicomponent mathematical models were developed and experimental data obtained for the simultaneous, competitive adsorption of six metal ions from an actual wastewater for both batch kinetic and semicontinuous packed-bed experiments. Experimental results indicated a selectivity order of Al > Cd > Zn > Ca > Mn > Mg and that metal ion breakthroughs were quite sensitive to ionic concentrations and adsorptive capacity. In addition, it was observed that, for the packed-bed experiments, the adsorptive capacity of the beads appeared to increase after the first few cycles. Mathematical models provided effective multicomponent equilibrium constants, adsorptive capacities, and reduced overall mass-transfer coefficients. The constants obtained from the packed-bed model were in reasonable agreement with those obtained from the batch kinetic model.