pH control

Aerosol pH controls important multiphase chemical pathways in the atmosphere but absolute values are poorly constrained. As part of the New England Air Quality Study, aerosol pH was quantified based on multiple independent approaches and results were intercompared for consistency. Soluble, reactive trace gases with pH-dependent solubilities (HNO3, NH3, HCl, HCOOH, and CH3COOH) were sampled with mist chambers. Size-segregated aerosols

A two-stage reverse osmosis (RO) process for high water recovery (up to 95%) desalination of Colorado River water was evaluated and demonstrated at the pilot scale. The two-stage process involved intermediate chemical demineralization (ICD) of the concentrate stream from a primary RO (PRO) process followed by secondary RO (SRO) desalting. Using alkaline-induced precipitation in a pilot-scale solids contact reactor (SCR), the membrane scaling propensity of the PRO desalting step was reduced, allowing for further recovery of product water via SRO of the demineralized PRO concentrate stream. When operating the SCR effluent above pH 10, the removal of Ca 2+ , Ba 2+ , Sr 2+ , and silica -the principal scale-forming precursors -were attained via ICD at levels upwards of 94%, 97%, 88%, and 67%, respectively. Despite significant process variations, 95% overall water recovery desalination was demonstrated to be feasible in the pilot scale via the PRO-ICD-SRO approach, with SRO desalting operated at specific permeate flux varying by ≤7% and at stable normalized salt passage of 2.9 ± 0.7% over extended periods of time. This study suggests that long-term implementation of the PRO-ICD-SRO process to achieve overall water recovery ≥95% would require robust on-line pH control strategy to attain consistent SCR effluent pH, along with appropriate selection and use of make-up antiscalants for the secondary RO desalting step, primarily to control membrane scaling by silicates and gypsum.

Several kinds of algal-based ecotechnologies are being studied for removing nutrients and sediments from polluted waters. Algae take up the pollutants through multiple mechanisms, and water quality is improved when the algal biomass is harvested. One of the benefits of this approach is that the harvested biomass is a byproduct of the water quality function and can be used in an economic process. In this study, data are reported on potential use of harvested algae to make a fertilizer. Building on earlier studies algae of known nutrient content that had been harvested from an algal turf scrubber in the Chesapeake Bay watershed, algae were added to potting soil in a plant growth experiment. The mass of algae added to the soil was scaled so that the amount of nitrogen added would be equivalent to the recommended commercial fertilizer application rate. Cucumber seeds were planted in the potting soil and their germination and plant height were compared between pots with algae fertilizer ...

A 15-litre bench-top multipurpose bioreactor was designed and constructed. The vessel is a glass type with a stainless flat headplate incorporating 9 access ports allowing for a variety of interchangeable probes and actuators. The stirring speed ranges between 0 and 250 rpm, the aeration rate (0-2 l/m), the pH control loop uses HI 1131 probe, two 100 ml bottles of HCl and NaOH solutions and operates a close feedback system. The temperature control module is a close loop using a PT 100 RTD thermocouple and an auxiliary vessel containing a cooling solution. The aeration and feed flow rates are open loops. The system incorporates attributes of a good bioreactor design as discussed by Naraendranathan (1998). Sterility is achieved by autoclaving different units of the system. This machine has been tested on an array of local standard fermentation processes.

The Rainbow hydrothermal field is located at 36°13.8 0 N-33°54.15 0 W at 2300 m depth on the western flank of a nonvolcanic ridge between the South AMAR and AMAR segments of the Mid-Atlantic Ridge. The hydrothermal field consists of 10-15 active chimneys that emit high-temperature ($365 °C) fluid. In July 2008, vent fluids were sampled during cruise KNOX18RR, providing a rich dataset that extends in time information on subseafloor chemical and physical processes controlling vent fluid chemistry at Rainbow. Data suggest that the Mg concentration of the hydrothermal end-member is not zero, but rather 1.5-2 mmol/kg. This surprising result may be caused by a combination of factors including moderately low dissolved silica, low pH, and elevated chloride of the hydrothermal fluid. Combining end-member Mg data with analogous data for dissolved Fe, Si, Al, Ca, and H 2 , permits calculation of mineral saturation states for minerals thought appropriate for ultramafic-hosted hydrothermal systems at temperatures and pressures in keeping with constraints imposed by field observations. These data indicate that chlorite solid solution, talc, and magnetite achieve saturation in Rainbow vent fluid at a similar pH (T,P) (400 °C, 500 bar) of approximately 4.95, while higher pH values are indicated for serpentine, suggesting that serpentine may not coexist with the former assemblage at depth at Rainbow. The high Fe/Mg ratio of the Rainbow vent fluid notwithstanding, the mole fraction of clinochlore and chamosite components of chlorite solid solution at depth are predicted to be 0.78 and 0.22, respectively. In situ pH measurements made at Rainbow vents are in good agreement with pH (T,P) values estimated from mineral solubility calculations, when the in situ pH data are adjusted for temperature and pressure. Calculations further indicate that pH (T,P) and dissolved H 2 are extremely sensitive to changes in dissolved silica owing to constraints imposed by chlorite solid solution-fluid equilibria. Indeed, the predicted correlation between dissolved silica and H 2 defines a trend that is in good agreement with vent fluid data from Rainbow and other hightemperature ultramafic-hosted hydrothermal systems. We speculate that the moderate concentrations of dissolved silica in vent fluids from these systems result from hydrothermal alteration of plagioclase and olivine in the form of subsurface gabbroic intrusions, which, in turn are variably replaced by chlorite + magnetite + talc ± tremolite, with important implications for pH lowering, dissolved sulfide concentrations, and metal mobility.

Sources of inorganic carbon (Ci) for photosynthesis and calcification and the mechanisms involved in their uptake in scleractinian corals were investigated in microcolonies of Galaxea fascicularis. Direct measurements of Ca 2 + , pH and O 2 on the surface and inside the polyp's coelenteron were made with microsensors. Gross photosynthesis (Pg) and net photosynthesis (Pn) were measured on the surface. Light respiration (LR) was calculated from Pg and Pn. The effect of light/dark and dark/light switches on Ca 2 + and pH dynamics on the surface and inside the coelenteron were followed. To evaluate the different sources of Ci for photosynthesis and calcification, Ci-free seawater and 6-Ethoxyzolamide and Acetazolamide, inhibitors for carbonic anhydrase (CA) were used. In normal seawater, Pg was about seven times higher than Pn, the LR was ca. 80 -90% of the Pg. Thus, most of the O 2 produced in Pg are immediately consumed in respiration, indicating the presence of a highly active internal C-cycle. As the internal C-cycle is highly active, a large part of the Ci for calcification will have passed through the metabolism of the symbiont. The high LR provides ATP for energy requiring processes in light. Ci for photosynthesis and calcification can come from seawater in the form of free Ci, respiration of photosynthates (internal C-cycle) or respiration of the ingested plankton. These sources form a common carbon pool (C-pool) that is used for the different processes. In Ci-free seawater, Pg decreased by about 12.5%, indicating that most of the photosynthetically fixed Ci can temporarily be supplied from internal sources. The initial decalcification, observed directly upon the switch to Ci-free seawater, showed that the Ca-pools in the coral are exchangeable. Part of the Pg in Ci-free seawater may depend on this decalcification for its Ci supply.

A fully automatic membrane inlet mass spectrometric (MIMS) on-line instrumentation for the analysis of aroma compounds in continuous beer fermentation processes was constructed and tested. The instrumentation includes automatic filtration of the sample stream, flushing of all tubing between samples and pH control. The calibration standards can be measured periodically. The instrumentation has also an extra sample line that can be used for off-line sample collection or it can be connected to another on-line method. Detection limits for ethanol, acetic acid and eight organic beer aroma compounds were from g l -1 to low mg l -1 levels and the standard deviations were less than 3.4%. The method has a good repeatability and linearity in the measurement range. Response times are shorter than or equal to 3 min for all compounds except for ethyl caproate, which has a response time of 8 min. In beer aroma compound analysis a good agreement between MIMS and static headspace gas chromatographic (HSGC) measurements was found. The effects of different matrix compounds commonly present in the fermentation media on the MIMS response to acetaldehyde, ethyl acetate and ethanol were studied. Addition of yeast did not have any effect on the MIMS response of ethanol or ethyl acetate. Sugars, glucose and xylose, increased the MIMS response of all studied analytes only slightly, whereas salts, ammonium chloride, ammonium nitrate and sodium chloride, increased the MIMS response of all three studied compounds prominently. The system was used for on-line monitoring of continuous beer fermentation with immobilised yeast. The results show that with MIMS it is possible to monitor the changes in the continuous process as well as delays in the two-phase process.

The nature and the action pattern of apoplastic pectinmethylesterase (PME) isoforms were investigated in mung bean [Vigna radiata (1.) Wilzeck] hypocotyls. Successive extractions of neutral and alkaline PME isoforms present in hypocotyl native cell walls (referred to as PE,, PE,, PE,, PE, , with increasingly basic isoelectric points) revealed that solubilization of PE,, PEZ, and PE, did not induce any significant decrease in the cell-wall-bound PME activity. The in vitro de-esterification occurring when isolated cell walls were incubated with pectin resulted, then, from the activity of PE,. In addition, p H control of PME activity was shown to be much stronger for enzymes bound to cell walls, in their native state or reintroduced after solubilization, than for enzymes in solution. Mature cell walls showed much more activity than young cell walls, and were relatively enriched in two acidic PME isoforms missing in young cell walls. One acidic PME was also detected in the extracellular fluid. The acidic and neutral isoforms that could be easily transferred from their binding sites to their substrate might be those involved in the demethylation process developing along the mung bean hypocotyl.

Sorbitol is a sugar alcohol largely used in the food industry as a low-calorie sweetener. We have previously described a sorbitol-producing Lactobacillus casei (strain BL232) in which the gutF gene, encoding a sorbitol-6phosphate dehydrogenase, was expressed from the lactose operon. Here, a complete deletion of the ldh1 gene, encoding the main L-lactate dehydrogenase, was performed in strain BL232. In a resting cell system with glucose, the new strain, named BL251, accumulated sorbitol in the medium that was rapidly metabolized after glucose exhaustion. Reutilization of produced sorbitol was prevented by deleting the gutB gene of the phosphoenolpyruvate: sorbitol phosphotransferase system (PTS Gut ) in BL251. These results showed that the PTS Gut did not mediate sorbitol excretion from the cells, but it was responsible for uptake and reutilization of the synthesized sorbitol. A further improvement in sorbitol production was achieved by inactivation of the mtlD gene, encoding a mannitol-1-phosphate dehydrogenase. The new strain BL300 (lac::gutF Δldh1 ΔgutB mtlD) showed an increase in sorbitol production whereas no mannitol synthesis was detected, avoiding thus a polyol mixture. This strain was able to convert lactose, the main sugar from milk, into sorbitol, either using a resting cell system or in growing cells under pH control. A conversion rate of 9.4% of lactose into sorbitol was obtained using an optimized fed-batch system and whey permeate, a waste product of the dairy industry, as substrate.

In the digester, it is necessary to organize periodic mixing of the substrate, which ensures the effective and stable operation of the BSU. The purpose of mixing is the release of biogas formed, mixing of fresh substrate and bacteria (grafting), preventing the formation of crust and sediment, preventing the formation of areas of different temperatures inside the digester, ensuring uniform distribution of the bacterial population, preventing the formation of voids and clusters that reduce the effective area of the digester. When choosing a mixing method, it should be taken into account that the fermentation process is a vital process of symbiosis of various bacterial strains, and if this community is destroyed, the fermentation process will be unproductive until a new bacterial community is formed. Therefore, too frequent or prolonged mixing is harmful. Slow mixing of the substrate every 4-6 hours is recommended. Optimal mixing of the feed increases biogas yield up to 50%. A comparat...

The purpose of the study was to investigate how effectively the penalty function methods are able to solve constrained optimization problems. The approach in these methods is to transform the constrained optimization problem into an equivalent unconstrained problem and solved using one of the algorithms for unconstrained optimization problems. Algorithms and matrix laboratory (MATLAB) codes are developed using Powell's method for unconstrained optimization problems and then problems that have appeared frequently in the optimization literature, which have been solved using different techniques compared with other algorithms. It is found out in the research that the sequential transformation methods converge to at least to a local minimum in most cases without the need for the convexity assumptions and with no requirement for differentiability of the objective and constraint functions. For problems of non-convex functions it is recommended to solve the problem with different starting points, penalty parameters and penalty multipliers and take the best solution. But on the other hand for the exact penalty methods convexity assumptions and second-order sufficiency conditions for a local minimum is needed for the solution of unconstrained optimization problem to converge to the solution of the original problem with a finite penalty parameter. In these methods a single application of an unconstrained minimization technique as against the sequential methods is used to solve the constrained optimization problem.

Ich möchte mich an dieser Stelle bei all denjenigen bedanken, die auf verschiedene Art und Weise zum Zustandekommen der vorliegenden Arbeit mit beigetragen haben. Mein besonderer Dank gilt Prof. Dr.-Ing. Dirk Weuster-Botz für die hervorragende Betreuung und dafür, dass er mir die Möglichkeit gegeben hat, für meine Promotion ein sehr anwendungsorientiertes Thema zu bearbeiten. Das Vertrauen und die Freiheit, die er mir dabei gewährt hat, zusammen mit seiner Präsenz, wenn Diskussionen über Engpässe notwendig wurden, haben mir ein optimales Arbeiten ermöglicht. Darüber hinaus habe ich auch die beratenden Gespräche bezüglich meiner weiteren Entwicklung sehr geschätzt. Ein weiteres Dankeschön geht an Dr. Heiner Schlieker, Dr. Peter Hohmann und Dr. Michael Hans von DSM Nutritional Products für die bemerkenswert offenen und konstruktiven Diskussionen und das persönlich sehr angenehme Klima während unserer Zusammenarbeit und für die Bereitstellung der Bacillus-Stämme.

The optimum culture dissolved oxygen concentration and culture pH for the production of cutinase from Fusarium solani pisi by the recombinant Saccharomyces cerevisiae SU50 strain was investigated. Dissolved oxygen concentrations in the fermentation culture of 5, 30 and 60% of air saturation were evaluated. A high cutinase production, specific cutinase activity and the highest cutinase yield on biomass and the highest specific cutinase production rate were obtained with a 5% of air saturation, which could have impact on process economics. Furthermore, at a low dissolved oxygen concentration, the specific growth rate, specific cutinase production rate, cutinase yield on biomass, cutinase activity and specific cutinase activity were increased when the pH control was changed from 5.25 to 6.25. The cutinase, accumulated in the yeast culture presents two glycosilated isoforms with molecular weights of 22.8 and 24.9 kDa measured by SDS-PAGE. Furthermore, cutinase in clarified culture samples presents a linear relationship between estereolytic and lypolitic activity and a high stability at room temperature.

Lactobacillus helveticus grown in milk with pH control at 6.2 had a slower growth rate (=0.27 h–1) and produced less exopolysaccharide (49 mg l–1) but increased lactic acid production (425 mM) compared to cultures without pH control (=0.5 h–1, 380 mg exopolysaccharide l–1, and 210 mM lactate), respectively. Both cultures displayed a mixed-acid fermentation with formation of acetate, which is linked not only to citrate metabolism, but also to alternative pathways from pyruvate.

Because of existing uncertainties and non-linearity characteristics of wastewater plants, highly affected by the state of the bacteria involved in each stage, their real-time control must follow an adaptive control rule. This paper presents the control strategy and fuzzy logic rules for a two stage anaerobic wastewater treatment plant in the food sector. PH, temperature and NaOH are controlled in the acidogenic reactor, and a second stage for ph and temperature control takes place in the methanogenic. The solution was tested ina simulated environment and was implemented on a pilot plant on a S7-300 PLC using simple IF.. THEN rules. We connected the plant to a remote Decision Support System to perform better state analysis, process optimization and abnormal situation management.

Experiments involving boron co-precipitation with calcite have been carried out inorganically under controlled pH conditions (7.9 Ϯ 0.05, 8.3 Ϯ 0.05 and 8.6 Ϯ 0.05) to determine the dependence of the boron isotopic composition (␦ 11 B) of calcite on the pH of seawater. Another purpose of these experiments was to estimate the magnitude of the biogenic influence on the ␦ 11 B value of foraminifera by comparing their boron isotopic composition with that of the inorganic calcite over a common pH range. The results show a clear relationship between ␦ 11 B of inorganic calcite and the pH of artificial seawater. The variation of boron isotopic fractionation between seawater and calcite with pH, estimated from these experiments, is similar to that estimated for cultured O. universa and the theoretically predicted trend. The results also support the hypothesis that B(OH) 4 Ϫ is the dominant species incorporated into the calcite structure. However, the boron isotopic fractionation between seawater and inorganic calcite is lower than that estimated for O. universa indicating the presence of a biogenic effect on the boron isotopic composition at least of this species of foraminifera. Most importantly, the results imply that in spite of a small biogenic influence on the boron isotopic composition of foraminifera, the variation in ␦ 11 B of foraminiferal shells with pH (at least for O. universa) is comparable to that for inorganic calcite, supporting the potential of this isotopic signature in foraminifera as a reliable paleo pH proxy.

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Water droplets or mist occur naturally in the air at seashores. These water droplets carry inorganic and organic substances from the sea to the land via the air, creating fertile land in sandy coastal areas (1). The same phenomenon occurs in an air-fluidized bed bioreactor (2). In an air-fluidized bed reactor, proteins can be transferred from the bioreactor semisolid bulk phase to an enriched droplet phase. This protein transfer process (droplet fractionation) can be experimentally simulated by shking a separatory funnel containing a dilute solution of a given protein, which can be an enzyme like invertase. The created droplets become richer in invertase (protein) than that of the original dilute solution. The droplets can then be coalesced by trapping them and recovering the concentrated protein in the new liquid phase. Typically, in such a droplet fractination process a collected enzyme can be degraded in its ability to catalyze a chemical reaction. In this article, we explore whether the initial solution pH control variable can be adjusted to minimize the decrease of enzyme activity in this process. The protein droplet recovery problem is one in which the recovered amount of desired protein (enzyme) in the droplet is maximized, subject to the minimization of the enzyme activity loss. The partitin coefficient, which is the ratio betweenthe protein concentration in the droplets and the residual solution, is maximized at approx 4.8 and occurs at pH 3.0. Here, the partition coefficient for invertase decreases as the initial solution pH increases between pH 3.0 and 8.0. Interestingly, the initial solution surface tension seems to be inversely proportional to the partition coefficient. The partition coefficient reaches a maximum value at a surface tension value of approx 63 mN/m at pH 3.0. The enzymatic activity of the initial, the residual, and the droplet solutions all decrease as the bulk solution pH increases. A decrease of enzymaticactivity was observed in the residual bulk solutionn when compared with that in the initial bulk solution at all pH levels. Also, up to 90% of the invertase activity was lost in the droplets when compared to the initial bulk solution.

When G. oxydans ATCC 621-H was grown in batch culture in a complex medium with glucose, ketogluconates were produced when the pH in the culture was maintained at 5.5. Without pH control gluconate was the only product of glucose oxidation, but at pH 5.5 the gluconate so produced was further oxidized to ketogluconates. Production of ketogluconates started when glucose was almost completely exhausted. It was shown that the actual glucose and gluconate concentrations in the culture do not determine the onset of ketogluconate formation during growth. Both 2 and 5 ketogluconate were produced. Addition of CaCO3 to the medium favored the production of 5 ketogluconate, However, under these conditions minor quantities of 2 ketogluconate were also formed. The sequential production of gluconate and ketogluconates from glucose was not only restricted to G. oxydans ATCC 621-H. A number of G. oxydans strains when grown under standard conditions in a pH controlled batch culture, all produced ketogluconates from glucose via an intermediate accumulation of gluconate. Although the ratios of the ketogluconates produced varied from strain to strain, all strains produced both 2 and 5 ketogluconate.

This research work presents a study of Top of the Line Corrosion (TLC) on carbon steels in the presence of carbon dioxide and acetic acid. The influence of different parameters such as the presence of mono-ethylene glycol (MEG) and the use of pH control were studied in a 4" diameter flow loop. Two sets of experiments were conducted; one at 70ºC, high CO 2 partial pressure and a "critical" condensation rate and another one at 80ºC, low CO 2 partial pressure and a high condensation rate. Weight loss techniques and surface analysis were used to evaluate the corrosion rate and products. It was found that the presence of HAc at the concentrations evaluated does not affect the general corrosion rate at the top of the line. Top of the line corrosion rates correlate with the De Waard / Lotz estimate of 10% of bottom of the line rates 15. It is believed that the corrosion mechanism is still controlled by CO 2 partial pressure at the experimental conditions evaluated in this study. The presence of MEG has not shown any effect on TLC due to the fact that the condensation rate was kept constant. The use of pH control in the supply

Sanitary landfill leachates are considered as heavily polluted industrial wastewaters, presenting significant time and spatial variations of their physical-chemical parameters. Special care is required for their efficient treatment and disposal. The main aim of this work was to examine the application of coagulation-flocculation for the treatment of raw and partially stabilized leachates. Jar-test experiments were employed in order to determine the optimum conditions for the removal of organic matter and color, i.e. coagulant-flocculant combination, effective dosage and pH control. Ferric chloride, aluminium sulphate and lime were tested as conventional coagulants, whereas four commercial polyelectrolytes were co-examined: one anionic, two cationic and a non-ionic polymer. High chemical oxygen demand (COD) removal capacities (about 80%) were obtained during the addition of ferric chloride to the partially stabilized leachates, whereas low COD reductions (i.e. lower than 35%) were measured during the addition of coagulants in the raw samples. The addition of polyelectrolytes and pH adjustment in the alkaline region were found to affect slightly the removal of pollutants. The physico-chemical process may be used as a useful pretreatment step, especially for fresh leachates, prior to biological treatment, or as a post-treatment (polishing) step for partially stabilized leachates.

Influência das variáveis de processo na etapa Ep do branqueamento ECF Influence of process variables of ECF Ep bleaching stage Palavras-chave: Branqueamento ECF, estágio alcalino, peróxido de hidrogênio, polpas kraft RESUMO As polpas kraft são de branqueamento difícil, pois que a lignina residual não se dissolve em um só estágio de aplicação de compostos clorados, sendo necessários múltiplos estágios e uma quantidade expressiva de reagentes para a obtenção de altos níveis de alvura. A inclusão de peróxido de hidrogênio no último estágio alcalino do branqueamento ECF (Elemental Chlorine Free) de polpas kraft é atualmente uma prática comum, pois incrementa a alvura e sua estabilidade, além de preservar a viscosidade das polpas e melhorar a qualidade dos efluentes. O presente trabalho consistiu em avaliar as variáveis de processo do estágio Ep de uma polpa kraft de pinho. Foi inicialmente aplicado um desenho fatorial fracionado, utilizando-se como variáveis a temperatura (72ºC-90ºC), o pH inicial (10,5 e 11,5), a concentração inicial de H 2 O 2 (0,2% e 0,4% sobre polpa a.s.-absolutamente seca) e dois tipos de quelantes (DTPA e DTPMPA) a 0,025% sobre polpa a.s. Foi simulado branqueamento em laboratório com consistência de 10% e com tempo de residência de 1h. As variáveis significativas para as propriedades ópticas das polpas foram: a temperatura, a concentração inicial de H 2 O 2 e o pH. Com os primeiros dois fatores foi aplicado um desenho experimental tipo central composto

One of foremost air-polluting which can be determined as being deterioration in the quality of the air is the emission of sulfur-dioxide gas. In this study, CaCO 3 solution which is one of the method used for the removal of the waste gas SO 2 from air was used. The neutralization of CaCO 3 with H 2 SO 4 was realized experimentally at the pH value that dissolution rate is maximum. The neutralization of limestone with H 2 SO 4 was realized in a stirred continuous reactor. pH value of the medium was controlled by utilizing self-tuning PID (STPID) algorithm and the on-line computer control system. ARMAX was used as the system model. A pseudo-random binary sequence (PRBS) was utilized as a forcing function in order to identify the dynamics of the process to be controlled and the system output was measured. The model parameters were evaluated by using Bierman algorithm. The tuning parameters of the STPID controller were determined.

Three Lactococcus strains (Lactococcus ssp. lactis var. diacetylactis, Lactococcus ssp. lactis cremoris and Lactococcus ssp. lactis var. lactis) isolated from the Tunisian lben were grown at constant pH on CSL medium in stirred fermentors for lactic starters production. The agitation required to homogenate alkali used to pH control should be low because it affects the Lactococcus growth. Scale up from 20-liter fermentor to 400-liter fermentor was carried out at constant impeller tip speed below 150 cm s A1. The CSL supplementation and fed-batch with glucose increased the yield in the upper 10 10 cfu/ml. The consumed glucose during fermentation was converted into lactic acid and cell. Before fed-batch, the maximum spe-ci®c growth rate of Lactococcus ssp. lactis var. diacetylactis was around 1 h A1 and the number of cells increased 20 to 40 times according to inoculum size. After fed-batch, the glucose consumption rate remains constant but speci®c growth rate decreased and number of cell trebled only.

Cu modified-MCM-22 has been prepared by hydrothermal crytalization from the resource of copper acetate solution. The properties of Cu-MCM-22 was charactered by XRD, SEM,TEM, TPR-H z mesurements. The catalytic activity of Cu-MCM-22 was tested DeNOx by propene .The resulst shown that Cu-MCM-22 contains two positions of copper after ion-exchange Cu 2 + ions and CuO particles nanosize, this catalyst has high activity in DeNOx by propene process from 260°C to 400°C.

Finely divided aspen and spruce woods and a high lignin pine kraft pulp have been selectively delignified to low lignin levels using aqueous solutions of polyoxometalates under anaerobic conditions. The reduced polyoxometalates in the solutions can be reoxidized with oxygen and act as wet oxidation catalysts for the mineralization of the solubilized lignin and carbohydrate fragments to carbon dioxide and water.

Polyoxometalates. Polyoxometalates (POMs), of which alpha-Keggin anions are representative, are a diverse and rapidly growing class of water-soluble cluster-anion structures with applications ranging from molecular catalysis to materials. [1] POMs are inexpensive, minimally or non-toxic, negatively charged clusters comprised of earlytransition-metals, usually in their d o electronic configurations (e.g. W(VI), Mo(VI), V(V), Nb(V), Ti(IV)), bridged by oxygens (formally oxide, or occasionally hydroxide ions). POMs have a number of attributes that render them attractive for applications in catalysis[2] and other technologies. For example, POMs exhibit extensive reversible redox processes,[3] and their reduction potentials, acidities, and other properties relevant to catalysis and materials science can be extensively yet readily altered by the elemental composition of the POM unit itself. For all the above reasons, yearly citations of articles on POMs have been growing steadily and, for each of the past three years, have outnumbered articles on fullerenes. Electron Transfer from POMs to O 2. The mechanism of O 2 reduction by POMs is of fundamental importance to all POM-catalyzed O 2 oxidations. Prior to the studies described here, it had been reported that isopoly-and heteropolytungstates in their reduced forms (H 2 W 10 O 32 4and P 2 W 18 O 62 7-) reduce O 2 without incorporation of 17 O into the POM products. While not unequivocal, these data are consistent with a mechanism that does not involve intermediate covalent W-O bonds and therefore, as in certain other POM reductions, is likely outer sphere. (In contrast, reaction of reduced polymolybdates with O 2 had been proposed for years, and was recently demonstrated by Neumann to proceed by an inner-sphere Mars van Krevelen-type mechanism). We now provide: (1) detailed kinetic data that unequivocally demonstrate that 1e-reduced alpha-Keggin anions, X n+ W 12 O 40 (7-n)-(X = Al(III), Si(IV), P(V)) reduce O 2 by an outer-sphere mechanism, and (2) the first systematic and quantitative evaluation of the role of heteroatom, X, on the reorganization energies, λ in , of alpha-Keggin anions. The reorganization energy, λ in is the sum of the energies associated with changes in atomic coordinates (bond lengths and

The application of liming material should consider the amount and quality of chemicals related to cost expenditure and target of expected soil properties since it is usually done with an incorrect number's estimation and expected soil-water quality which produces unsuccessful results. This study aimed to analyze the effect of different percentages from each combination of dolomite and hydrated lime (DH); DH1 (75:25), DH2 (50:50), and DH3 (25:75), which used five replications to the soil and water quality. The soil samples were taken from the earthen pond of semi-intensive tilapia fish (Oreochromis niloticus) culture in Lat Bua Luang, Rangsit, Thailand, placed into 50 plastic pots (volume = 1.5 L), and mixed with lime of different compositions. Based on the results, the mixture of dolomite and hydrated lime (DH) increased the soil and water pH into the desirable ranges (7.4-8.6). The alkalinity of DH treatments was not higher than that of the single dolomite (DA) or hydrated lime (HA). However, the value was still sufficient (>75 mg/L as CaCO 3) to buffer water quality changes. Several depletions of the toxic materials (total aluminum, iron, and manganese) caused by sulfuric acid from pyrite (FeS2) oxidation had been observed in combination treatment, especially in DH1. On the contrary, the essential base cations, calcium, and magnesium increased beyond the single treatment, either dolomite (DA) or hydrated lime (HA). A combination of dolomite and hydrated lime (DH1) as an alternative treatment to remedy aquaculture ponds in acid-containing soil is suggested in terms of efficiency and possible cost-effectiveness.

Copper ion-exchanged and impregnated iron-pillared interlayer clays (Fe-PILCs), prepared by using copper solutions with different pH values and copper precursors, were tested in the selective catalytic reduction (SCR) of NO x by propene. Low pH values led to dehydroxylation of the iron pillars and damages in the clay structure. Samples prepared without pH control presented isolated Cu 2+ ions; those prepared by using alkaline pH solutions presented Cu 2+ ions and CuO clusters. It was observed that the presence of Cu 2+ ions accompanied by CuO clusters led to an improvement in the NO x yield to N 2 , which was in agreement with the best activity for C 3 H 6 combustion showed by these catalysts. The best catalytic results were obtained with samples prepared by ion exchange with copper II acetate under alkaline pH, where Cu 2+ ions and CuO clusters were simultaneously formed in an adequate proportion.

Electrical conductivity was used for characterizing the production of cheese starters on pilot and industrial scales. The variation of pH and conductivity with time was followed during growth of cultures used for Cheddar cheese production. Pilot-scale fermentations were carried out in triplicates with eight mesophilic mixed cultures, without pH control and mixing, in reconstituted milk. Industrial fermentations were performed for four of the eight starters with similar operating conditions. The "rst derivatives of pH and conductivity with time were calculated numerically from neural network models and several kinetic parameters were identi"ed, speci"cally maximum acidi"cation and conductivity rates of change (< , VG ) with corresponding times, and the pH and conductivity at which < and VG occurred. The conductivity was shown to be an adequate measurement for providing valuable information on the course of the fermentation process and the starter activity on the two production scales.

A secretion cassette, based on the expression and secretion signals of a S-layer protein (SlpA) from Lactobacillus brevis, was constructed. E. coli b-lactamase (Bla) was used as the reporter protein to determine the functionality of the S-layer signals for heterologous expression and secretion in Lactococcus lactis, Lactobacillus brevis, Lactobacillus plantarum, Lactobacillus gasseri and Lactobacillus casei using a low-copy-number plasmid derived from pGK12. In all hosts tested, the bla gene was expressed under the slpA signals and all Bla activity was secreted to the culture medium. The Lb. brevis S-layer promoters were very efficiently recognized in L. lactis, Lb. brevis and Lb. plantarum, whereas in Lb. gasseri the slpA promoter region appeared to be recognized at a lower level and in Lb. casei the level of transcripts was below the detection limit. The production of Bla was mainly restricted to the exponential phase of growth. The highest yield of Bla was obtained with L. lactis and Lb. brevis. Without pH control, substantial degradation of Bla occurred during prolonged cultivations with all lactic acid bacteria (LAB) tested. When growing L. lactis and Lb. brevis under pH control, the Bla activity could be stabilized also at the stationary phase. L. lactis produced up to 80 mg/l of Bla which to our knowledge represents the highest amount of a heterologous protein secreted by LAB so far. The short production phase implied a very high rate of secretion with a calculated value of 5×105 Bla molecules/cell per h. Such a high rate was also observed with Lb. plantarum, whereas in Lb. brevis the competition between the wild type slpA gene and the secretion construct probably lowered the rate of Bla production. The results obtained indicate wide applicability of the Lb. brevis slpA signals for efficient protein production and secretion in LAB.

A mathematical model has been created for the process of citric acid biosynthesis by yeast (mutant strain Yarrowia lipolytica) cultivated by the repeated batch (RB) method on ethanol under conditions of nitrogen limitation. The model accounts for cell growth as a function of nitrogen concentration in the culture liquid; nitrogen uptake by growing cells; citric acid production; pH control in the fermentor by means of NaOH addition; and changes in system volume. The model represents a system of five nonlinear differential equations. Experimental measurements of cell concentration, citric acid concentration, and cultivation broth volume were used with the least squares method to determine the values of eight model parameters. The parameter values obtained were consistent with literature data and general concepts of cell growth and citric acid biosynthesis. The model has been used to predict optimum RB culture conditions.

In the bio-scorodite process, arsenic is precipitated as crystalline iron arsenate, i.e. scorodite (FeAsO 4 •2H 2 O). This is a more economic and more environmentally friendly method for arsenic immobilization than the chemical production of iron-or calcium arsenate, as fewer chemicals are needed. Moreover, scorodite is an attractive medium for arsenic control and immobilization because it is stable, compact and has a very low solubility. Therefore it is regarded as the most ideal form for long-term arsenic storage. We have demonstrated that bio-crystallization of arsenic into scorodite crystals is possible with the aid of microorganisms. The operational conditions of the bio-scorodite process allow for a fast growth of the microorganisms and facilitate the crystallization of scorodite, avoiding the precipitation of other iron oxides or amorphous iron arsenates. The bio-scorodite process brings several advantages compared to chemical crystallization such as the lower required temperature (70°C), the control of supersaturation by biological oxidation and no need for crystal parents or seeds to begin the crystallization. Arsenic concentrations are removed to ppm level with starting concentrations ranging from 1000 to 2000 mg L-1. The produced bioscorodite crystals are very similar to the scorodite mineral found in nature. By control of the iron feed and the pH, the production of other iron precipitates is avoided. The latter facilitates easy separation of the solid product. Based on their highly crystalline nature, the biogenic scorodite crystals seem very suitable for safe disposal. At present the research has started with the continuous production of scorodite in bioreactors. The follow-up challenges are focused on the selection of a suitable reactor configuration.

pH control for multistep enzymatic synthesis reactions is important due to its potential industrial applications; however, it becomes d$ficult when the optimal pH for the individual steps of the reaction pathway differs by se~~eral units. The usual approach of using a compromised pH is neither satisfactory nor always feasible. An optimal pH control technique has been developed which allows a tie-step reaction to occur simultaneously in proxirniw to each other and at their respective optimal pH in a single reactor. This technique separates the microenvironments of the two steps of a reaction pathway by coating an immobilized enzyme pellet with a thin layer sf urease. Ammonia generated by the hydrolysis of urea consumes the hydrogen ions d@using from the acidic bulk solution into the immobilized enzyme pellet. In this paper, the pH control technique is demonstrated jar a two-step reaction where salicin is first converted by P-glucosidase to saligenin and glucose, followed by the isomerization of glucose catalyzed by glucose isomerase. The technique allows this two-step reaction to ta!ir place simultaneously at their respective optimal pH values of 5.0 j?)r P-glucosidase and 8.0 jar gluc~~se isomerase.

This study investigates the roles of both ionized and unionized species of flavopiridol in solubilization by complexation, micellization, and cosolvency. Control of pH was used in combination with surfactants (polysorbate 20 and polysorbate 80), cosolvents (ethanol and propylene glycol), as well as uncharged and anionic complexing agents [hydroxypropyl-cyclodextrin (HP CD) and sulfobutyl ether-cyclodextrin (SBE CD)] to solubilize flavopiridol. These combined techniques increase not only the solubility of the un-ionized flavopiridol but also the solubility of the ionized drug. This study confirms that previously developed equations effectively characterize the roles of pH, pK a , and either complexation constant, micelle partition coefficient, or cosolvent solubilizing power in determining drug total aqueous solubility.

Ammonium salts represent a major component of fine mode marine aerosol that play an important role in climate regulation, atmospheric pH control and nutrient supply to the oceans. We report here the results of analyses of aerosol samples collected in remote areas of the Atlantic Ocean. We show the isotopic abundance of aerosol ammonium varies with concentration, with isotopically light ammonium (−5 to −8‰) associated with the lowest ammonium concentrations compared to isotopically heavy ammonium (+10‰) associated with higher ammonium concentrations. We interpret the light ammonium signature as arising from marine emissions of ammonia. These results provide further evidence for the existence of a marine ammonia source and offers a method to define the relative contribution of marine and terrestrial ammonium to aerosols in remote areas and thereby investigate the role of these emissions in climate regulation.

The Rhizobium sp. T1 strain, which induces nodule formation on alfalfa and clover roots, produces, during growth, an extracellular polysaccharide composed of D-glucose and D-glucuronic acid noted glucoglucuronan. During the bacterial growth, the pH of the medium decreases slightly. The control of pH in the growth medium slightly reduces the glucoglucuronan production. Under the conditions tested in the present work, the weight-average molecular weight of the polymers produced with or without pH control are similar: Mw :2× 10 6 ; the repeating unit determined by chemical and NMR analyses corresponds to the disaccharide: 3)-b-D-GlcpA-(14)-b-D-Glcp-(1.

Carbonate in soil from karst region is a substantial carbon sink on Earth. Many karst regions are covered by Pdeficient soil. This study evaluated the influences of phosphate addition on fungal weathering (by typical phosphate-solubilizing fungus Aspergillus niger) of carbonate in the soil with red color from karst region. Two weathering pathways were recognized, i.e., biochemical and biomechanical deterioration. The biochemical pathway was performed by dissolving carbonate via secreting organic acids. Meanwhile, the dominant organic acid, i.e., oxalic acid, induced the formation of calcium oxalate, which prevented the loss of Ca 2+ cations. It was estimated that the ideal carbonate solubilization driven by geological fluorapatite and fungal weathering is up to 3.3% per year, based on the equation of 12 × (R Base + R PSF) × m × (A real /A PSF). Moreover, fungal weathering of carbonate is very sensitive to the solubility of phosphates. Phosphates supply essential P source for the fungal growth and subsequently raise water-soluble P content in the soil. The addition of bioapatite (a variety of natural apatite with relatively high solubility) elevated the value to 4.6% (a~40% enhancement compared with FAp). This research hence elucidated the tight correlation between carbonate weathering and P supply. Inorganic C release driven by P availability and microbial weathering should be addressed in karst region.

Candida sp. strain SY16 produces a glycolipidtype biosurfactant, mannosylerythritol lipid (MEL-SY16), which can reduce the surface tension of a culture broth from 72 to 30 dyne cm −1 and highly emulsify hydrocarbons when cultured in soybean-oil-containing media. As such, laboratory-scale fermentation for MEL-SY16 production was performed using optimized conditions. In batch fermentation, MEL-SY16 was mainly produced during the stationary phase of growth, and the concentration of MEL-SY16 reached 37 g l −1 after 200 h. The effect of pH control on the production of MEL-SY16 was also examined in batch fermentation. The highest production yield of MEL-SY16 was when the pH was controlled at 4.0, and the production was significantly improved compared to batch fermentation without pH control. In fed-batch fermentation, glucose and soybean oil (1:1, w/w) were used in combination as the initial carbon sources for cell growth, and soybean oil was used as the feeding carbon source during the MEL production phase. The feeding of soybean oil resulted in the disappearance of any foam and a sharp increase in the MEL production until 200 h, at which point the concentration of MEL-SY16 was 95 g l −1. Among the investigated culture systems, the highest MEL-SY16 production and volumetric production rate were achieved with fed-batch fermentation.

When the yeast Saccharomyces cerevisiae was grown under aerobic continuous culture conditions with a medium containing ethanol as carbon source, an autonomous sustained metabolic oscillation appeared. This oscillation was observed in rates and concentrations of various parameters such as, ethanol, oxygen uptake rate, carbon dioxide evolution rate, NaOH addition rate for pH control, acetate, and intracellular pH. No changes were observed in concentrations of stock carbohydrates. Intracellular pH changes were out of phase with oxygen uptake rate, which was reverse of the results with glucose-based oscillation. These results suggested that changes in glycolytic flux and intracellular pH were not regulating the oscillation. Analysis suggested that one of the oscillatory regulation points was located in the ethanol assimilation pathway.

In this paper an overview is given of a new biotechnological process to remove hydrogen sulphide from gas streams. This process is jointly developed by Wageningen University, Delft University of Technology, Paques B.V. and Shell Global Solutions International B.V. In 1992, the first full-scale installation for H 2 S removal from biogas was taken into operation whilst in 2002 the first unit for high pressure natural gas desulphurisation was started-up. The removal of sulphur dioxide from flue gasses is feasible as well and in 2006 the first unit went on-stream in China. Currently, more than 75 full-scale plants are in operation worldwide. The formed bio-sulphur has a hydrophilic nature which enables its re-use, e.g. as a fertilizer or fungicide. 1 RELEASE OF SULPHUR-CONTAINING GASSES INTO THE ATMOSPHERE The increase in global population from 6 billion people in 2005 towards an expected number of 9 billion in 2050 is inevitably associated with a continued industrialization, urbanization and motorization. Without doubt, this will lead to a strong growth of the need for energy, especially in countries such as India and China that are on the eve of an industrial revolution. According to the International Energy Agency the energy consumption will increase with some 60 per cent in 2030 whilst in 2050 the global CORE Metadata, citation and similar papers at core.ac.uk Provided by Repositorio da Universidade da Coruña

In this paper an overview is given of a new biotechnological process to remove hydrogen sulphide from gas streams. This process is jointly developed by Wageningen University, Delft University of Technology, Paques B.V. and Shell Global Solutions International B.V. In 1992, the first full-scale installation for H 2 S removal from biogas was taken into operation whilst in 2002 the first unit for high pressure natural gas desulphurisation was started-up. The removal of sulphur dioxide from flue gasses is feasible as well and in 2006 the first unit went on-stream in China. Currently, more than 75 full-scale plants are in operation worldwide. The formed bio-sulphur has a hydrophilic nature which enables its re-use, e.g. as a fertilizer or fungicide. 1 RELEASE OF SULPHUR-CONTAINING GASSES INTO THE ATMOSPHERE The increase in global population from 6 billion people in 2005 towards an expected number of 9 billion in 2050 is inevitably associated with a continued industrialization, urbanization and motorization. Without doubt, this will lead to a strong growth of the need for energy, especially in countries such as India and China that are on the eve of an industrial revolution. According to the International Energy Agency the energy consumption will increase with some 60 per cent in 2030 whilst in 2050 the global CORE Metadata, citation and similar papers at core.ac.uk Provided by Repositorio da Universidade da Coruña

On-line estimation of lactic acid produced by Lactobacitlus casei in a pilot scale reactor coupled with a microfiltration module is performed by measuring the conductance on the permeate effluent. Non-interference by other ions (inorganic and organic) present in the medium has been verified. This method is found more reliable that the estimation of lactate concentration from the amount of alkaline solution supplied for the pH control.

A Celulose Nipo-Brasileira é uma das maiores produtoras de celulose kraft branqueada de eucalipto no Brasil. Produz 860.000 tsa/ano em duas linhas, que são equipadas com digestores contínuos. Ambas as linhas fabricam polpa ECF (Elemental Chlorine Free) com as seqüências Dhot(EOP)D(EP)D e D(EOP)DP, respectivamente, na linha 1 e 2. A fábrica tem tratamento do efluente com lodo ativado com dois tanques de aeração com capacidade para 20.000 m³, equipados com aeradores superficiais seguidos por quatro clarificadores secundários (dois para cada reator). Nas últimas décadas, a fábrica tem otimizado e vem mudando seus processos, a fim de melhorar a preservação ambiental. Com o objetivo de reduzir o volume de efluente, DQO e carga de AOX, a seqüência Ahot(EOP)D(PO) proposta foi avaliada em testes laboratoriais, com reciclagem de filtrado parcial. Este artigo propôs a reciclagem de filtrado, que reduz o volume de efluente da fábrica em 9 m³/tsa (tonelada secada ao ar), isto é, mais ou menos 5...

Trees dominate terrestrial biotic weathering of silicate minerals by converting solar energy into chemical energy that fuels roots and their ubiquitous nutrientmobilising fungal symbionts. These biological activities regulate atmospheric CO 2 concentrations ([CO 2 ] a) over geologic timescales by driving calcium and magnesium fluvial ion export and marine carbonate formation. However, the important stabilising feedbacks between [CO 2 ] a and biotic weathering anticipated by geochemical carbon cycle models remain untested. We report experimental evidence for a negative feedback across a declining Cenozoic [CO 2 ] a range from 1500 to 200 ppm, whereby low [CO 2 ] a curtails mineral surface alteration via trenching and etch pitting by arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungal partners of tree roots. Optical profile imaging using vertical scanning interferometry reveals changes in nanoscale surface topography consistent with a dual mode of attack involving delamination and trenching by AM and EM fungal hyphae on phyllosilicate mineral flakes. This is consistent with field observations of micropores in feldspar, hornblende and basalt, purportedly caused by EM fungi, but with little confirmatory evidence. Integrating these findings into a process-based biotic weathering model revealed that low [CO 2 ] a effectively acts as a "carbon starvation" brake, causing a threefold drop in tree-driven fungal weathering fluxes of calcium and magnesium from silicate rock grains as [CO 2 ] a falls from 1500 to 200 ppm. The feedback is regulated through the action of low [CO 2 ] a on host tree productivity and provides empirical evidence for the role of [CO 2 ] a starvation in diminishing the contribution of trees and mycorrhizal fungi to rates of biological weathering. More broadly, diminished tree-driven weathering under declining [CO 2 ] a may provide an important contributory mechanism stabilising Earth's [CO 2 ] a minimum over the past 24 million years.