Kinetic Modelling

This research work evaluates the impact of stormwater infiltration on the removal of organics, solids, nitrogen and phosphorus in a LECA-based horizontal subsurface flow constructed wetland. Stormwater runoff for the period between January 2008 and June 2010 (30 months) was estimated for the drainage basin of the Vila Fernando wastewater treatment plant (constructed wetland system) and it was observed proportionality between the increase in surface runoff and the infiltration flow rate that reached the plant. The average stormwater infiltration rate that reached the plant was 67.4 m(3) d(-1) (77% of the influent flow rate into the plant). The 30 month monitoring campaign set up at one of the reed beds showed that stormwater infiltration led to a high variation of the hydraulic loading rate (HLR) throughout the bed, which affected its performance in the removal of organic matter, suspended solids and nitrogen. For a HLR below 20 cm d-1 the removal efficiencies for BOD5, COD and TSS doubled. The removal of nitrogen was too low and was associated with the weak development of nitrifying biofilm and the poor growth of reeds. However, it was observed a good relationship between the applied and removed loads for most of the parameters, which seems to indicate that the organic, solid, nitrogen and phosphorus loading rates influenced the respective removal rates. The use of a bed material with high specific surface area, such as LECA, can only improve the treatment capacity of horizontal subsurface flow systems if the organic and solid loading rates, as well as the HLR, can be effectively controlled.

A kinetic model is presented giving a mathematical description of batch culture of Pseudomonas putida PGA1 grown using saponified palm kernel oil as carbon source and ammonium as the limiting nutrient. The growth of the micro-organism is well-described using Tessier-type model which takes into account the inhibitory effect of ammonium at high concentrations. The ammonium consumption rate by the cells is related in proportion to the rate of growth. The intracellular production of medium-chain-length poly-(3-hydroxyalkanoates) (PHAMCL) by P. putida PGA1 cells is reasonably modeled by the modified Luedeking-Piret kinetics, which incorporate a function of product synthesis inhibition (or reduction) by ammonium above a threshold level.

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Nitrogen (N) cycle involves a complex set of potential biochemical pathways with reactions catalyzed by different microorganisms. Elementary mass balances for COD, DO, NH4-N and alkalinity were conducted and stoichiometric relationships were investigated to explain possible pathways of the nitrogen removal mechanisms in a lab-scale submerged down flow biological packed bed (BPB) reactor. Four sets of experiments were performed by modifying the organic loading and C/N ratio in comparison with steady-state conditions. Approximately 90% of COD and NH4-N removal occurred in two upper sections occupying 1/5 of the reactor height. The elementary
mass balances could not explain all the experimental results with respect to nitrogen removal and oxygen consumption by known mechanisms. The mass balance calculations, excluding the possibility of nitrification, were in general in accordance with the observations indicating no or minimal NO3-N production. The theoretical stoichiometric requirements for nitrification reaction
were satisfied in 6 experiments and in another 8 experiments nitrification may have occurred, but stoichiometry was not satisfied. Using C/N ratio as the variable, only at C/N ratio = 10, the predictions confirmed the possibility of nitrification in the same 3 (out of 4) assays as observed in practice. The results of this study reveal that the nitrogen transformations occurring in the studied reactor are complex and cannot be explained by simple mechanisms of microbial assimilation and nitrification.

The discharge of Palm Oil Mill Effluent (POME) to river or sewage has caused serious environmental problems for the past several decades. This has prompted many researchers to find alternative technologies such as the use of an ultrasonic-assisted membrane anaerobic system, also known as UMAS. However, further use of UMAS in treating POME tends to create blockage on the membrane surface, which is commonly known as membrane fouling. In this study, kinetic parameters of POME samples which contributed to the fouling were investigated, namely; the biomass growth rate, μ max and substrate utilization rate, K s. Two different sources of POME samples were taken from namely; a final discharge pond at Felda Sungai Tengi, Selangor and decanter processing units at Felda Jengka, Pahang. The POME samples were treated by UMAS in a 26-Litre laboratory reactor which operated 5 h per day for a HRT of 7 days so as to observe their performance in terms of percentage COD removal and CH 4 production. Performance results revealed that maximum COD removal efficiencies were 82.75% and 94.43% for the final discharge pond and decanter processing unit samples respectively. All these data were collected and curve fitting methods were then used to construct appropriate profiles for μ max and K s following a Monod model. It was found that the high OLR sample (decanter) apparently yielded better efficiency of POME treatment (i.e. calculated μ max of 0.327 day À1 , K s of 0.361 g COD/g VSS. d, and volume of CH 4 gas produced at 25 m 3) compared to that of low OLR sample from ponds (i.e. calculated μ max of 0.237 day À1 , K s of 0.1674 g COD/VSS. d, and volume of CH 4 gas produced at 9 m 3). In conclusion, it shows that UMAS is a promising treatment to treat POME in which its calculated kinetic coefficients of μ max and K s are similar to the theoretical values when Monod Model

A clear and relatively simple algorithm for generating a unique (canonical) form of the reaction mechanism is presented based on symbolic algebra and SMILES (Simplified Molecular Input Line Entry System)/USMILES (Unique SMILES)language. This algorithm allows comparing and/or merging of different mechanisms and is useful for modeling complex reactions such as combustion. A computer program for generating the canonical form of the mechanism, called CANMECH (CANon-izedMECHanism), is available from the authors. The only required input to the program is the text file that translates species names used in the original mechanism to its SMILES counterparts or any other form, containing connectivity information. The algorithm is illustrated with example mechanisms in the CHEMKIN format.

Several lines of evidence demonstrate involvement of serotonin 1A receptors (5-HT 1A Rs) in the pathophysiology of neuropsychiatric disorders such as depression, suicidal behavior, schizophrenia, and Alzheimer's disease. We recently published the synthesis and initial evaluation of [O-methyl-11 C]2-(4-(4-(2methoxyphenyl)piperazin-1-yl)butyl)-4-methyl-1,2,4-triazine-3,5 (2H,4H)dione ( 11 C-MMP), a 5-HT 1A R agonist. Here we determine the optimal modeling parameters for 11 C-MMP under its new name, 11 C-CUMI-101, in Papio anubis. Methods: PET scans were performed on 2 adult male P. anubis; 166.5 MBq 6 43.0 (4.50 6 1.16 mCi) of 11 C-CUMI-101 were injected as an intravenous bolus, and emission data were collected for 120 min in 3-dimensional mode. We evaluated 4 different models (1-and 2-tissue compartment iterative and noniterative kinetic models, basis pursuit, and likelihood estimation in graphical analysis [LEGA]), using binding potential (BP F 5 B max /K d ) (B max 5 maximum number of binding sites; K d 5 dissociation constant) as the outcome measure. Arterial blood sampling and metabolitecorrected arterial input function were used for full quantification of BP F . To assess the performance of each model, we compared results using 6 different metrics (percentage difference, withinsubject mean sum of squares [WSMSS] for reproducibility; variance across subjects, intraclass correlation coefficient [ICC] for reliability; identifiability based on bootstrap resampling of residuals; and time stability analysis to determine minimal required scanning time) at each of 6 different scanning durations. Models were also evaluated on scans acquired after injecting the 5-HT 1A antagonist [N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl) cyclohexane carboxamide] [WAY100635] 0.5 mg/kg, intravenous) and the 5-HT 1A agonist 8-hydroxy-2-(di-n-propylamino) tetralin) [8-OH-DPAT] 2 mg/kg, intravenous). Results: All metabolites are more polar than 11 C-CUMI-101, and no significant change in metabolites was observed in the blocking studies. The free fraction is 59% 6 3%. We determined that 100 min of scanning time is adequate and that for the region-of-interest (ROI)-level analysis, the LEGA model gives the best results. The median test-retest percentage difference for BP F is 11.15% 6 4.82% across all regions, WSMSS 5 2.66, variance 5 6.07, ICC 5 0.43, and bootstrap identifiability 5 0.59. Preadministration of WAY100635 and 8-OH-DPAT resulted in 87% and 76% average reductions in BP F values, respectively, across ROIs. Conclusion: On the basis of the measurable free fraction, high affinity and selectivity, adequate blood-brain permeability, and favorable plasma and brain kinetics, 11 C-CUMI-101 is an excellent candidate for imaging high-affinity 5-HT 1A Rs in humans.

A monitoring campaign in a horizontal subsurface flow constructed wetland under the influence of transient loads of flow-rate, organic matter, nitrogen and suspended solids showed an irregular removal of COD and TSS and lower both removal efficiencies and mass removal rates than the ones observed in other studies for similar operating conditions. This circumstance is associated to the presence of large amount of particulate organic matter from non-point sources. The mass removal rate of ammonia increased 39% as both the water and soil temperatures increased from weeks 1–8 to weeks 9–14. A good correlation between mass load and mass removal rate was observed for all measured parameters, which attests a satisfactory response of the bed under to transient loads.

Water has a precious value and each drop must be accounted-for in water scarce regions such as the Middle East and North Africa. Therefore, wastewater has to be reclassified as a renewable water resource rather than waste. This helps in augmenting water availability, and at the same time in preventing environmental pollution. Utilization of this resource requires collection, treatment, and use of all generated wastewater. Although reuse of wastewater is recognized in most water-scarce countries, the reuse of wastewater is still very low. This paper analyzes the major components of a sustainable wastewater reuse scheme. It also reviews the different methods that are frequently used to quantify and report progress and achievements in wastewater reuse. The paper also introduces an alternative yardstick named by the author as the wastewater Reuse Index (WRI) that has a value between 0-100; WRI is calculated by dividing the amounts of wastewater being actually reused by the total amounts of wastewater generated at country level. WRI enables water resource managers and policy-makers to put a figure on the gap between achievements at different junctures. Moreover, WRI recognizes water saving efforts such as low water consumption and reducing losses; thus, highlights the way forward for improving the reuse efficiency as an integral part of water resources management. The paper highlights the major barriers to extensive reuse of the reclaimed wastewater in the MNEA countries.

Scholarly Abstract Water has a precious value and each drop must be accounted-for in water scarce regions such as the Middle East and North Africa. Therefore, wastewater has to be reclassified as a renewable water resource rather than waste. This helps in augmenting water availability, and at the same time in preventing environmental pollution. Utilization of this resource requires collection, treatment, and use of all generated wastewater. Although reuse of wastewater is recognized in most water-scarce countries, the reuse of wastewater is still very low. This paper analyzes the major components of a sustainable wastewater reuse scheme. It also reviews the different methods that are frequently used to quantify and report progress and achievements in wastewater reuse. The paper also introduces an alternative yardstick named by the author as the Wastewater Reuse Index (WRI) that has a value between 0-100; WRI is calculated by dividing the amounts of wastewater being actually reused b...

The removal of Volatile Fatty Acids (VFA) , from wastewater deriving from numerous sources such as chemical plants has been an area of research interest for more than a century. With the global petroleum resources facing scarcity and the constantly rising awareness of the environmental impact the carbon based economy has created , research has been focused in developing alternative methods of their production, such as biofermentation. In biofermentation, the hydrolysis of target solid wastes followed by the microbial conversion of them to biodegradable organic content results in the production of intermediate organic acids, specifically VFA. VFA are detected at high concentrations in the effluent streams and mixed liquors of anaerobic membrane reactor systems, because of sudden variations in hydraulic and organic loading rates. Several studies have shown possible environmental and commercial benefits using filtration as a source separation process in comparison to integral wastewater treatment. These benefits include the relief of municipal treatment plants, the use of favourable nutrients and the composition of urine free wastewater for biotreatment. and insufficient capacity of microfiltration and ultrafiltration systems for their rejection, mainly due to their low molecular weight. Anaerobic effluents need to be treated with a more advanced treatment process such as nanofiltration and reverse osmosis.

A clear and relatively simple algorithm for generating a unique (canonical) form of the reaction mechanism is presented based on symbolic algebra and SMILES (Simplified Molecular Input Line Entry System)/USMILES (Unique SMILES)language. This algorithm allows comparing and/or merging of different mechanisms and is useful for modeling complex reactions such as combustion. A computer program for generating the canonical form of the mechanism, called CANMECH (CANon-izedMECHanism), is available from the authors. The only required input to the program is the text file that translates species names used in the original mechanism to its SMILES counterparts or any other form, containing connectivity information. The algorithm is illustrated with example mechanisms in the CHEMKIN format.

A low-cost biosorbent hybrid material ready for application was obtained in this work. Yerba mate (Ilex paraguariensis) milling residual dust was used as a polyphenol source by ethanolic extraction. Polyphenols were immobilized within a SiO(2) matrix to form an interpenetrated polymer after glutaraldehyde cross-linking. Pb(II), Cr(III) and Cr(VI) were chosen as model metals for adsorption. The hybrid materials were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and Nitrogen Adsorption Isotherms. Adsorption experimental data were analysed using Langmuir, Freundlich, Dubinin-Radushkevich, Temkin, Redlich-Peterson, Sips and Toth isotherm models along with the evaluation of adsorption energy and standard free energy (ΔG°). The adsorption was observed to be pH dependent. The main mechanism of metal adsorption was found to be a spontaneous charge associated interaction. Electron Spin Resonance (ESR) spectroscopy confirmed that Cr(VI) adsorption was an adsorption-coupled reaction and the adsorbed specie was Cr(V). The hybrid matrix probed its adsorption capacity of Cr(III) in a non-treated tannery wastewater.

The stability of ascorbic acid and colour intensity in pasteurised blood orange juice (Citrus sinensis [L.] Osbeck) during one month of storage was investigated at 4-37 °C. The effects of ascorbic acid fortification (at 100, 200 mg L −1) and deaeration, temperature/time storage on the kinetic behaviour were determined. Ascorbic acid was monitored by HPLC-DAD and colour intensity by spectrophotometric measurements. Degradation kinetics were best fitted by first-order reaction models for both ascorbic acid and colour intensity. Three models (Arrhenius, Eyring and Ball) were used to assess the temperature-dependent degradation. Following the Arrhenius model, activation energies were ranged from 51 to 135 kJ mol −1 for ascorbic acid and from 49 to 99 kJ mol −1 for colour intensity. The effect of storage temperature and deaeration are the most influent factors on kinetics degradation, while the fortification revealed no significant effect on ascorbic acid content and colour intensity.

This work assesses the effects of various amino acids, including serine, alanine, methionine, and proline, on calcium tartrate tetrahydrate (CTT) crystals. The crystallization experiments were performed in batch mode at 25 °C, pH 9 with three amino acid concentrations. The CTT crystals were characterized by XRD, FTIR, SEM, particle size and zeta potential analysis. All of the amino acids used in this study were found to significantly affect the surface electrical charge, size, and morphology of the obtained crystals. In addition, the thermal decomposition of the produced crystals obtained in pure media was examined and the obtained data were used to investigate the decomposition kinetics of the crystals with the help of three different model-free kinetic methods, namely Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Starink. The average activation energy of the crystals for the first, second, third, and fourth stages using the FWO, KAS, and Starink methods was calculated to be 91.0, 158.0, 249.1, and 224.8 kJ/mol; 89.6, 155.9, 250.7, and 221.1 kJ/mol; 88.6, 156.8, 250.5, and 220.4 kJ/mol, respectively. Thus, the results of this work are useful for selecting CTT morphology modifiers and explaining the decomposition kinetics of CTT crystals.

Multiple-open-tubular columns enabling transverse diffusion (MOTTD) are made of straight, parallel, and cylindrical flow channels separated by a mesoporous stationary phase. In Part 1, a model of band broadening along MOTTD columns accounting for longitudinal diffusion, the trans-channel velocity bias, and mass transfer resistance in the stationary phase was proposed and validated. In this Part 2, the model is completed by considering the impact of short-range inter-channel velocity biases on the MOTTD plate number. These velocity biases are caused by the wide distribution of the channel diameters. Different ratios, ρ, of the average inner diameter, 2 < r c >, of the flow channels to their closest center-to-center distance d (d = 5 μm, ρ = 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9) with a relative standard deviation (RSD) increasing from 0 to 50% are considered. The zone retention factor k 1 was increased from 1 to 25. The complete model of band broadening is validated after adjustment to dispersion data obtained by 1) the lattice-Boltzmann method for modeling fluid flow, 2) a random-walk particle-tracking (RWPT) technique to address advective-diffusive transport, and 3) by considering two distinct populations of flow channels (inner radii r c, 1

An indigenous purple non-sulfur bacteria Rhodopseudomonas palustris PBUM001 was used to produce hydrogen gas via batch photofermentation of palm oil mill effluent (POME). The photofermentation hydrogen production was carried out in a 5-l reactor (B. Braun Biostat V R B) with a working volume of 3.5 l (height: 39 cm and diameter: 16 cm) under anaerobic condition. The stirred tank reactor (STR) was conducted at temperature, 30 6 2 C; POME concentration, 100% (v/v); light intensity, 4.0 klux; pH 6, inoculum size, 10% (v/v); agitation rate, 250 rpm, and operated for 66 h. Two sets of experiments were run in STR (R1 and R2) and the data obtained were used for kinetic study of photofermentation hydrogen production. Unstructured models were used to describe the bacterial growth, substrate consumption, and hydrogen gas production by R. palustris PBUM001. The discrepancy between the proposed model and the experimental data in simulating hydrogen production from POME by R. palustris PBUM001 was measured by using residual sum of squares (RSS). Logistic model could be adopted to describe the kinetics of bacterial growth (RSS: 0.3039-0.2313) and the proposed model for substrate consumption agreed well with the experimental data obtained in this study as shown by its RSS value of 19.1319 and 26.8259 for R1 and R2, respectively. A modified Leudeking-Piret model was applied for the data fitting to determine the relationship between the cell growth and photofermentation hydrogen production (RSS: 1.3267-26.3741). V

A monitoring campaign in a horizontal subsurface flow constructed wetland under the influence of transient loads of flow-rate, organic matter, nitrogen and suspended solids showed an irregular removal of COD and TSS and lower both removal efficiencies and mass removal rates than the ones observed in other studies for similar operating conditions. This circumstance is associated to the presence of large amount of particulate organic matter from non-point sources. The mass removal rate of ammonia increased 39% as both the water and soil temperatures increased from weeks 1-8 to weeks 9 -14. A good correlation between mass load and mass removal rate was observed for all measured parameters, which attests a satisfactory response of the bed under to transient loads.

Nitrogen (N) cycle involves a complex set of potential biochemical pathways with reactions catalyzed by different microorganisms. Elementary mass balances for COD, DO, NH 4 -N and alkalinity were conducted and stoichiometric relationships were investigated to explain possible pathways of the nitrogen removal mechanisms in a lab-scale submerged down flow biological packed bed (BPB) reactor. Four sets of experiments were performed by modifying the organic loading and C/N ratio in comparison with steady-state conditions. Approximately 90% of COD and NH 4 -N removal occurred in two upper sections occupying 1/5 of the reactor height. The elementary mass balances could not explain all the experimental results with respect to nitrogen removal and oxygen consumption by known mechanisms. The mass balance calculations, excluding the possibility of nitrification, were in general in accordance with the observations indicating no or minimal NO 3 -N production. The theoretical stoichiometric requirements for nitrification reaction were satisfied in 6 experiments and in another 8 experiments nitrification may have occurred, but stoichiometry was not satisfied. Using C/N ratio as the variable, only at C/N ratio = 10, the predictions confirmed the possibility of nitrification in the same 3 (out of 4) assays as observed in practice. The results of this study reveal that the nitrogen transformations occurring in the studied reactor are complex and cannot be explained by simple mechanisms of microbial assimilation and nitrification.

A monitoring campaign in a horizontal subsurface flow constructed wetland under the influence of transient loads of flow-rate, organic matter, nitrogen and suspended solids showed an irregular removal of COD and TSS and lower both removal efficiencies and mass removal rates than the ones observed in other studies for similar operating conditions. This circumstance is associated to the presence of large amount of particulate organic matter from non-point sources. The mass removal rate of ammonia increased 39% as both the water and soil temperatures increased from weeks 1-8 to weeks 9 -14. A good correlation between mass load and mass removal rate was observed for all measured parameters, which attests a satisfactory response of the bed under to transient loads.

This research work evaluates the impact of stormwater infiltration on the removal of organics, solids, nitrogen and phosphorus in a LECA-based horizontal subsurface flow constructed wetland. Stormwater runoff for the period between January 2008 and June 2010 (30 months) was estimated for the drainage basin of the Vila Fernando wastewater treatment plant (constructed wetland system) and it was observed proportionality between the increase in surface runoff and the infiltration flow rate that reached the plant. The average stormwater infiltration rate that reached the plant was 67.4 m 3 d −1 (77% of the influent flow rate into the plant). The 30 month monitoring campaign set up at one of the reed beds showed that stormwater infiltration led to a high variation of the hydraulic loading rate (HLR) throughout the bed, which affected its performance in the removal of organic matter, suspended solids and nitrogen. For a HLR below 20 cm d −1 the removal efficiencies for BOD 5 , COD and TSS doubled. The removal of nitrogen was too low and was associated with the weak development of nitrifying biofilm and the poor growth of reeds. However, it was observed a good relationship between the applied and removed loads for most of the parameters, which seems to indicate that the organic, solid, nitrogen and phosphorus loading rates influenced the respective removal rates. The use of a bed material with high specific surface area, such as LECA, can only improve the treatment capacity of horizontal subsurface flow systems if the organic and solid loading rates, as well as the HLR, can be effectively controlled.

This study was on the technical and biological characteristics of a partial-SHARON submerged-filter bioreactor of 3 L. The main focus was the influence of the hydraulic retention time (HRT) on biofilms. For this purpose, we used molecular tools based on the partial 16S rRNA genes. The results showed that the HRT may affect the nitrification processes of a bioreactor using synthetic
wastewater containing 600 mg/L of ammonia. It was found
that an HRT of 0.5 day transformed 100 % of the ammonium
into nitrite. However, when the HRT was decreased to 0.4 day, there was a significant reduction (35 %) in the quantity of ammonia transformed, which confirmed the complexity of the system operation. Moreover, a PCRTGGE approach highlighted the differences observed. The results obtained showed that an HRT of 0.5 day reduced bacterial biodiversity in the biofilms, which were mainly formed by Nitrosomonas and Diaphorobacter. In contrast, an HRT of 0.4 day facilitated the formation of heterogeneous biofilms formed by nitrifying bacteria, such as Nitrosomonas sp., Nitrosospira sp., and Nitrosovibrio sp.).