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The hydrogen-producing bacteria SP4 and SP6 were isolated from the compost and identified by 16S rRNA gene sequencing as Clostridium butyricum and Clostridium beijerinckii , respectively. A comparative study on the biohydrogen-producing activity of the isolated strains was carried out using mono-, di- and tri-saccharides belonging to both hexoses (maltose, glucose, mannose, fructose, lactose, galactose, sucrose, raffinose, cellobiose) and pentoses (xylose). To assess the biotechnological significance, real wastewater rich in sugars (cheese whey, confectionery wastewater, sugar beet processing wastewater) was also used as a substrate. C. butyricum SP4 fermented sugars with a yield of 0.93–1.52 mol H 2 /mol hexose (pentose); the maximum yield was obtained from fructose, the minimum – from raffinose and cellobiose. The most preferred substrate for C. beijerinckii SP6 was sucrose with a yield of 1.76 mol H 2 /mol hexose, while cellobiose yielded only 0.64 mol H 2 /mol hexose. Overall, the efficiency of converting wastewater to H 2 by C. butyricum SP4 was also slightly lower (66–93 ml H 2 /g chemical oxygen demand (COD)) than that of C. beijerinckii SP6 (76–103 ml H 2 /g COD). Even though the main soluble metabolite products (SMPs) for both isolates were acetate and butyrate, C. butyricum SP4 also produced a significant amount of ethanol (up to 21.5% of SMPs) and formate (up to 32.5% of SMPs), and C. beijerinckii SP6 – lactate (up to 25% of SMPs). A distinctive feature of C. beijerinckii SP6 was a significantly lower (almost 2 times) yield of SMPs, while C. butyricum SP4 had a higher rate of H 2 production according to the results obtained from the kinetic study using the modified Gompertz equation and the first order equation. Analysis of Spearman's rank correlation coefficients revealed a statistically significant relationship between the kinetic parameters of H 2 production and the concentration of butyrate and the final pH of the medium for C. butyricum SP4, and with the concentration of ethanol for C. beijerinckii SP6. These findings provide valuable information on the metabolic capabilities of the most studied hydrogen-producing representatives of the Clostridium genus for their use in optimizing the technology for biohydrogen production by dark fermentation of various organic wastes. [ABSTRACT FROM AUTHOR]

The results of modelling the effect of cell sizes on the microorganism disintegration process are presented. Experiments were conducted in a horizontal bead mill for baker's yeast Saccharomyces cerevisiae. The kinetics of the cell disruption process was investigated by optical image analysis and the release of intracellular protein by Bradford method. A large variation in the size of yeast from one production cycle has been demonstrated. A significant increase in the constant rate of the process with an increase in the range of the cell size class was demonstrated. More beneficial values of the coefficient of determination were obtained for the spherical model of the cell. Worse results of the process description were obtained for the ellipsoidal model. They may result from large variations in cell volume in individual size classes. The greatest changes in the cell Elongation parameter within one size class ranged from 1.00 to 1.54. Unlabelled Image • The theory of random transformation of dispersed matter were used for modelling. • Baker's yeast Saccharomyces cerevisiae has very different cell sizes and shapes. • The rate constant of yeast disintegration depends on the size of cells. • Process description results are better for a spherical cell model then ellipsoidal. • The resultant of linear component processes is a linear total process. [ABSTRACT FROM AUTHOR]

To explore the process kinetics of hydrogen evolution reaction (HER) on carbon-based Ni/NiO nanocomposite in the microbial electrolysis cells (MECs), the performance was systematically studied by different time-course sampling of five parallel single-chamber MECs operated under identical operating conditions, which included the electrochemical performance of anodes and cathodes, and the mechanism and kinetics of HER. It was hypothesized that the decreased performance of the nickel cathodes was due to corrosion and Ni dissolution. These results provide valuable insights into the effects of long-term operation on MEC performance. Image 1 • The time-course investigation into HER in a MEC. • The process kinetics of HER in a MEC. • Long-term HER shows correlation with characterisation variation of Ni/NiO. [ABSTRACT FROM AUTHOR]

Abstract Hydrogen (H 2) is considered as fuel for future and its biological production from renewable feedstocks is very promising. Dark fermentation of fruit-vegetable waste (FVW) and cottage cheese whey (CCW) for the production of H 2 constitutes a promising way for combining energy generation and lignocellulosic waste management. In this work, process kinetics of biohydrogen production via dark fermentation of FVW and CCW by pretreated anaerobic sludge inocula were investigated. To inhibit H 2 consuming methanogens, the effects of various inoculum pretreatment, viz., 2-bromoethanesulfonate, heat-shock, acid, alkali, UV, and ultrasonication on H 2 -production were investigated which revealed 2-bromoethanesulfonate, heat-shock and acid-treated inoculum resulted in maximum bioH 2 production and yield of 118.12 ± 1.05, 93.37 ± 1.3, 96.32 mMol/L and 1.66, 1.22 ± 0.01, 1.39 ± 0.02 mMol/gCOD initial , respectively. The effects of system initial pH, substrate to inoculum (S 0 /X 0) and carbon to nitrogen (C/N) ratio on H 2 -production were evaluated which revealed maximum H 2 production and yield could be achieved at pH 7, S 0 /X 0 of 10.6 g COD /g VS , and C/N 26.8. Modified Gompertz model and Modified Logistic model were used to define various kinetic parameters pertaining to cumulative H 2 -production which showed high R 2 values (≥0.98). The influence of pH on H 2 and ethanol/volatile fatty acids production kinetics were evaluated using Andrew's and Ratkowsky's model showing relatively good R 2 values (≥0.62). Remarkably high production of ethanol (2.43 ± 0.28 mg/L) was noticed alongside H 2 production at pH 7 suggesting that bioethanol can be recovered at the end of fermentative H 2 production. Terminal Restriction Fragment Length Polymorphism and 16s rDNA sequencing revealed dominance of 9 bacterial species such as Escherichia coli , Clostridium butyricum , Streptococcus henryi , and 6 others uncultured bacteroides. This research determined different kinetic parameters for an enhanced H 2 production strategy by co-fermentation of FVW and CCW providing an understanding of process behavior which will in turn help in the upscaling of the H 2 -production processes. Graphical abstract Unlabelled Image Highlights • Various inoculum pretreatments were evaluated to maximize H 2 production. • Characterization of H 2 production from co-fermentation of fruit-vegetable waste and cheese whey. • Kinetic analyses of H 2 production using various unstructured mathematical models. • Microbial population analysis of consortium was conducted using t-RFLP and 16s rDNA sequencing. [ABSTRACT FROM AUTHOR]

Self-assembly of nanoscale materials represents the prevailing bottom-up strategy toward constructions of nanoarchitectures with hierarchical structures and desirable functionalities. Differentiated from the synthesis-then-assembly approach which involves organization of preformed uniform nanoparticles (NPs), the synthesis-cum-assembly , where the formation and the assembly of the primary NPs occur simultaneously within the same experimental settings is endowed with inherent advantages in building functional architectures of well-defined morphologies, hierarchical structures, controllable dimensions, permanent stability and excellent processability. Current methodologies to operate synthesis-cum-assembly could be broadly divided into three major categories: (i) the process involving solid particles as both precursors and templates, such as SiO 2 beads, coordination polymer colloidal particles, inorganic–organic supermolecules, metal/metal oxides; (ii) the one assisted with inertial templates such as micelles, vesicles and emulsions of various amphiphiles including surfactants, polymers and biomolecules; and (iii) the template-free case which is relatively less reported. Salient features of these methods were analyzed and compared by selecting typical studies, in order to demonstrate the working principles in each approach. This review puts emphasis upon strategies to balance the process kinetics between the chemical reactions of generating primary NPs and the physical assembly process; the various postsynthetic modifications and applications of 1D–3D endproducts gained from various synthesis-cum-assembly studies toward heterogeneous catalysis, adsorptions, electrocatalysis, lithium-ion batteries etc ., are also covered, and future research directions are present as well. [ABSTRACT FROM AUTHOR]

The study investigated the effect of sludge age on substrate utilization kinetics, soluble microbial product generation, and composition of the microbial community sustained in asuperfast submerged membrane bioreactor(SSMBR). For this purpose, a laboratory-scale membrane bioreactors (MBR) unit was operated at steady state, with three different sludge ages in extremely low range of 0.5–2.0 d, and a hydraulic retention time of 8.0 h. Substrate feeding was adjusted to 220–250 mg COD/L and involved a synthetic mixture representing the readily biodegradable COD fraction in domestic sewage. The MBR operation at sludge age of 1.0 d was duplicated with acetate feeding as the sole organic carbon source. Under different operating conditions,SSMBR was able to secure complete removal of available soluble/readily biodegradable substrate, with a residual microbial product level as low as 20–30 mg COD/L, partly retained and accumulated in reactor volume. Phylogenic analysis based on polymerase chain reactions-denaturing gradient gel electrophoresis analysis indicated that selected sludge ages affected the composition of microbial community. Lower sludge ages selected a community characterized by faster rates for microbial growth. Results confirmed the existence of a functional relationship between variable process kinetics and changes in the microbial community structure, even for slight variations that can be inflicted on the culture history while operating superfast MBR systems. [ABSTRACT FROM AUTHOR]

The study evaluated the chronic impact of sulfamethoxazole on metabolic activities of fast growing microbial culture. It focused on changes induced on utilization kinetics of acetate and composition of the microbial community. The experiments involved a fill and draw reactor, fed with acetate and continuous sulfamethoxazole dosing of 50 mg/L. The evaluation relied on model evaluation of the oxygen uptake rate profiles, with parallel assessment of microbial community structure by 454-pyrosequencing. Continuous sulfamethoxazole dosing inflicted a retardation effect on acetate utilization in a way commonly interpreted as competitive inhibition, blocked substrate storage and accelerated endogenous respiration. A fraction of acetate was utilized at a much lower rate with partial biodegradation of sulfamethoxazole. Results of pyrosequencing with a replacement mechanism within a richer more diversified microbial culture, through inactivation of vulnerable fractions in favor of species resistant to antibiotic, which made them capable of surviving and competing even with a slower metabolic response. [ABSTRACT FROM AUTHOR]

Highlights: [•] Full substrate removal with super fast membrane bioreactor at high loading. [•] Permeate COD lower than 50mg/L attributed to soluble microbial products. [•] Entrapment of soluble products due to membrane effective filtration size (8–14nm). [•] Major changes in the composition of the microbial culture at high substrate loading. [ABSTRACT FROM AUTHOR]

The physicochemical regularities of chemical vapor deposition (CVD) of nickel films from bis-(ethylcyclopentadienyl) nickel [(EtCp)2 Ni] have been experimentally studied for two reaction systems: (EtCp)2 Ni–H2–Ar and (EtCp)2 Ni–Ar. A model reaction scheme of (EtCp)2 Ni transformations has been developed in accordance with the data from the time-of-flight mass-spectrometry of the reaction gas phase. The results from a study of process kinetics and morphology of the deposited layers show that the growth process is controlled by nucleation step in the deposition temperature range 760–840K in case of (EtCp)2 Ni pyrolysis and within the interval 640–810K when hydrogen is added (at P[(EtCp)2 Ni]=75Pa). The values of activation energy of the processes are 189±9 and 115±6kJ·mol−1 for the temperature ranges mentioned, respectively. [ABSTRACT FROM AUTHOR]

Highlights: [•] Microbial population structure was assessed using sequencing of 16S rRNA gene. [•] Different microbial community was observed when the culture history was changed. [•] Model evaluation indicated variable process kinetics as function of culture history. [•] Change in the microbial community was a major factor for variable process kinetics. [Copyright &y& Elsevier]

Abstract: The study evaluated the fate of grey water in a membrane bioreactor (MBR). It mainly involved the evaluation of system performance based on modeling biodegradation characteristics of grey water. The investigation was conducted on grey water using a pilot-scale MBR operated at a sludge age of 60 days. The system secured full removal of biodegradable organics with only 10mg/L residual COD in the effluent, suitable for reuse. Model calibration of cyclic dissolved oxygen profiles fitted the experimental data and defined all related model coefficients with a lower maximum growth rate and lower hydrolysis rates compared with domestic sewage. Model simulation using process kinetics confirmed full removal of available biodegradable COD and generation of soluble microbial products. Significantly, higher soluble COD levels in the bulk liquid compared with the process effluent could be explained by means of cake filtration in the membrane, capturing larger fractions of soluble residual COD. Consequently, entrapment and partial biodegradation of soluble residual organics ensured the very low levels of effluent COD. [Copyright &y& Elsevier]

Abstract: The study evaluated the biodegradation characteristics of a mixture of organics with different biodegradation characteristics in an integrated chemical plant effluent. The wastewater had a total chemical oxygen demand (COD) content of 12,800mg/L, mostly soluble and 93% biodegradable. The evaluation was based on respirometry, and mainly consisted on model calibration and interpretation of the oxygen uptake rate data, which exhibited an original and specific profile with a sequence of two peaks and three plateaus. A specific model was defined for this purpose, which identified four different biodegradable COD components with significantly different process kinetics. The major fraction accounting for 57% of the total biodegradable COD in the wastewater had to be hydrolyzed before biodegradation with a low hydrolysis rate of 1.3day−1. The analysis of the experimental data showed that the oxygen utilization started with a delayed response after substrate addition. The delayed logarithmic phase could be characterized by a Haldane type of inhibition kinetics. [Copyright &y& Elsevier]

Abstract: This paper evaluated the effect of mixing the effluent of a pharmaceutical plant producing acetylsalicylic acid with tannery wastewater, on the biodegradation of the effluents. The evaluation involved the analysis of the oxygen uptake rate (OUR), profiles of each wastewater and the mixture by respirometry. Model calibration using the experimental OUR data identified major COD fractions and associated process kinetics for all samples analyzed. The tannery sample was a plain-settled effluent having a total COD of around 2200mg/L with a readily biodegradable fraction of 15%. The same fraction was 57% in the pharmaceutical wastewater sample having a much stronger total COD content of 40,435mg/L. Consequently, mixing of the pharmaceutical effluent with the tannery wastewater up to 38% of the total COD in the mixture increased the readily biodegradable COD fraction but had an inhibitory effect on the biodegradation kinetics. This effect was relatively lower on growth, but quite significant on the hydrolysis of the slowly biodegradable COD decreasing the maximum hydrolysis rate from 2.0day−1 to 1.2day−1. Model evaluation of the respirometric data, as performed in this study sets a workable protocol for the assessment of the compatibility of different wastewater mixtures for biological treatability. [Copyright &y& Elsevier]

Hydrogen sulfide absorption and oxidation by corroding concrete surfaces was quantified in a test rig consisting of 6 concrete pipes operated under sewer conditions. The test rig was placed in an underground sewer monitoring station with access to fresh wastewater. Hydrogen sulfide gas was injected into the pipe every 2nd hour to peak concentrations around 1000 ppm. After some months of operation, the hydrogen sulfide became rapidly oxidized by the corroding concrete surfaces. At hydrogen sulfide concentrations of 1000 ppm, oxidation rates as high as 1 mg S m−2 s−1 were observed. The oxidation process followed simple nth order kinetics with a process order of 0.45–0.75. Extrapolating the results to gravity sewer systems showed that hydrogen sulfide oxidation by corroding concrete is a fast process compared to the release of hydrogen sulfide from the bulk water, resulting in low gas concentrations compared with equilibrium. Balancing hydrogen sulfide release with hydrogen sulfide oxidation at steady state conditions demonstrated that significant corrosion rates—several millimeters of concrete per year—can potentially occur at hydrogen sulfide gas phase concentrations well below 5–10 ppm. The results obtained in the study advances the knowledge on prediction of sewer concrete corrosion and the extent of odor problems. [Copyright &y& Elsevier]

Abstract: Results of studies on the disruption of cells depending on the concentration of microorganism suspension are presented. Studies were conducted using baker’s yeast Saccharomyces cerevisiae. The process was carried out in a horizontal bead mill. The cell disruption kinetics was determined based on the number of living microorganisms. Computer microscopic image analysis was applied. It was proved that growing disruption rate constants of cells which appear with an increase of the concentration of microorganisms suspension excludes a possibility of using a linear description of general process modelling. Based on the analysis of cell size distribution and spatial location of yeast cells in the continuous phase, it was found that the mutual relations between cells intensified with an increase of their concentration. The initial number of cells and their disintegration degree has an influence on the process run. Hence process conditions change during the disintegration. A non-linear model based on mass transfer described cell wall disruption. Hypotheses concerning a non-linear run of the process are given. [Copyright &y& Elsevier]

The process kinetics of the mesophilic (35 °C) anaerobic digestion of ice-cream wastewater was investigated. The Monod equation and the Contois equation were used to develop two basic steady-state models. The kinetic parameters required for the application for the steady-state models were determined using a laboratory-scale continuously stirred tank reactor (5 l) fed with a synthetic ice-cream wastewater at a range of hydraulic retention times (2.99–7.45 days). Both models were evaluated with a set of routine analytical data obtained from a pilot-scale (5 m3) anaerobic contact digester treating the ice-cream wastewater at a commercial site. The steady-state model obtained with the Contois equation was more suitable than that obtained with the Monod equation for describing the process kinetics of the pilot-scale anaerobic contact process. The main reason for this is that the kinetic model based on the Contois equation considers the effect of any changes in influent substrate concentration in its prediction. [Copyright &y& Elsevier]

• Acute SMX impact was evaluated by modelling, for all processes of mixed culture. • Acute SMX exposure revealed partial peptone mixture binding/blockage. • SMX caused non-competitive inhibition on nitritation and nitratation. • SMX slightly affected substrate storage and subsequent substrate utilization rates. • Enhanced endogenous respiration is linked to higher maintenance energy requirement. This study explored acute impact of sulfamethoxazole (SMX) on mixed microbial culture by means of respirometric analysis and modeling of process kinetics. The culture was developed in a laboratory-scale activated sludge reactor fed with peptone mixture. The reactor was maintained at steady state at SRT of 10 days allowing the culture to sustain both heterotrophic and autotrophic fractions. Response of biomass under pulse feeding of 50 mg/L and 200 mg/L SMX was determined by monitoring corresponding oxygen uptake rate (OUR) profiles. Model calibration of OUR profiles enabled numerical assessment of the repressive action of SMX on all processes, heterotrophic growth; substrate binding and storage; two-step nitrification; endogenous respiration. The maximum growth rate of Nitrite Oxidizing Bacteria (NOB) was reduced by 35 %, compared to a slight decrease for Ammonia Oxidizing Bacteria (AOB). Upon exposure, significant substrate binding of around 40–50 % by SMX was observed, drastically reducing the amount of available carbon source for microbial growth. Substrate was directed towards storage with a 15–25% increase in the maximum storage rate. Pulse exposure to 200 mg/L of SMX induced a 50 % increase in the endogenous respiration rate, presumably to meet a higher need for maintenance energy potential for resistance and survival. [ABSTRACT FROM AUTHOR]

• We introduce the concept of self-optimizing attainable regions. • The concept defines performance targets under temperature uncertainty. • Incorporating uncertainty reduces operating limits but increases robustness. • Digester structures as opposed to single digesters increase operating limits. • Economic decisions can now be made under conditions of uncertainty. Uncertainty in operating parameters such as temperature undermines the reliability of using kinetic models in performance projections for plants operated under ambient non-isothermal conditions. This study develops a theoretical framework, which uses process kinetics, uncertainty quantification to define robust operating limits known as self-optimizing attainable regions, where by instead of defining a very large operating limit, which will be achieved some of the times for some of the reactor configurations, we define a self-optimizing limit, which will be achieved all the times for all possible reactor configurations (despite variations in temperature). Using a temperature range of 20 – 60∘ C , , the results indicate that decreasing temperature uncertainty, increasing process temperature or using a multistage digester structure increases the self-optimizing operating limits: 1.53 × 10 − 4 , 4.95 × 10 − 4 and 6.32 × 10 − 4 (g / L) 2 obtained for temperatures of 20.00, 31.60 and 52.40∘ C respectively. The findings highly important in defining performance targets especially when there is uncertainty in environmental conditions. [ABSTRACT FROM AUTHOR]

• Ethanol showed high potential for Mangiferin extraction from Mangifera indica leaves. • Leaf age, time, temperature and feed to volume ratio affected yield of bio compound. • Peleg model fitted the process kinetic data's to a greater extent. • Liquid phase molecular diffusion transport phenomena were analyzed. An analysis of extraction method using different solvents for efficient obtention of bioactive compounds from plant sources is very important because there is a large demand for these compounds in the food, pharmaceutical and other allied industries. Mangiferin, a phenolic compound, present in large proportion in mango leaves and is endow to have exceptional antioxidant property apart from demonstrating remarkable prospective demand in nutraceutical, cosmetic and food industries. In the present investigation, the extraction by solvent modus operandi was followed to extract the mangiferin compound from mango leaves. The effect of solvent type, age of leaf, time of extraction (1–6 h) and extraction temperature (40–70 °C) on the recovery of mangiferin were investigated. It was inferred that the yield of mangiferin from young leaves and old leaves were 22.28% and 10.74% respectively at the optimum condition. The extraction efficiency of four solvents ethanol, acetone, ethyl acetate and hexane were evaluated. The extraction method using ethanol as solvent was considered to be productive because significant quantity of desired compound was obtained. This can be attributed to the polar characteristic of the extracting agent. The optimized extraction time, temperature and sample mass to solvent volume ratio for maximum mangiferin extraction were found to be 6 h, 70 °C and 1:15 respectively. The rate of extraction was analyzed using first and second order kinetic model and the parameters were evaluated using linear regression technique. The extraction process rate constant and temperature were linearly related with an activation energy factor 20.25 kJ/mol. Thermodynamic factors which include activation enthalpy (ΔH*) and activation Gibb's free energy (ΔG*) were evaluated and it was concluded that the process is endothermic and non-spontaneous in identity. The intra particle diffusion coefficient was estimated using Wilke Chang model. The result concluded that the diffusion coefficient of active component is directly proportional to temperature. The applicability of Peleg model and logarithmic model to narrate the kinetics of the solid-liquid extraction process were tested. Based on the significance of the statistical parameters, it can be ascertained that Peleg model has a fine agreement with the experimental values. The regression coefficient was found to be high in Peleg model (R2 = 0.9923) with least Root Mean Squared Deviation RMSD value of 0.0135 confirms the applicability of this model. [ABSTRACT FROM AUTHOR]