Long-term evaluation of a sequential batch reactor (SBR) treating dairy wastewater for carbon removal.

Many dairy industries have been using SBR wastewater treatment plants because they allow optimal working condition to be reached. However, to take advantage of SBR capabilities, strong process automation is needed. The aim of this work is to study the factors that influence SBR performance to improve modelling and control. To better understand the whole process we studied the kinetic modelling, the carbon removal mechanism and the relation between reactor performance, aerobic heterotrophic activity and bacterial population dynamics (by terminal restriction fragment length polymorphisms of 16S rDNA, T-RFLP). The heterotrophic activity values presented high variability during some periods; however, this was not reflected on the reactor performance. As sludge health indicator, the average activity in a period was better than individual values. Although all the carbon removal mechanisms are still unclear for this process, they seemed to be influenced by non-respirometric ways (storage, biosorption, accumulation, etc.). The variability of heterotrophic activity could be correlated with the bacterial population diversity over time. Despite the high variability of the activity, a simple kinetic model (pseudo ASM1) based on apparent constant parameters was developed and calibrated. Such modellisation provided a good tool for control purposes.     

Characterization by CO/FTIR spectroscopy of Pd/silica catalysts and its correlation with syn‐gas conversion

Well‐dispersed Pd catalysts, supported on two morphologically different silicas (meso‐ and microporous Davison G59 and G03 grades, respectively) and used for syn‐gas activation at T=493–523 K and P=1–4 MPa (CO/H₂= 1/2.5), have been studied by CO chemisorption using FTIR spectroscopy. The long‐term exposure to 760 Torr CO(g) at 298 K produces deep changes on the surface structure of Pd particles on both supports. The Pd particles become rougher and/or show more open crystal planes. This phenomenon of surface restructuring seems to depend both on the exposed metal fraction (FE) of palladium and the morphology of the support. The rate of surface restructuring but not its extent, is a function of the superimposed CO(g) pressure. On the microporous G03 silica CO chemisorbs in multicoordinated or “hollow” sites (H band), but these signals are not shown by preparations of the supported metal of comparable dispersity on mesoporous G59 grade. Terminal (L band) and di‐coordinated CO_s (B band) appear in both types of catalysts. The high‐loading preparations on the microporous support showed a higher proportion of Pd(111) planes than those of low Pd loading, which seems to contribute to the high TOF_CH4 and high selectivity to methane in syn‐gas activation of these catalysts, while the remaining ones show excellent capability for methanol production. This revised version was published online in July 2006 with corrections to the Cover Date.     

Marked intra-strain variation in response of Listeria monocytogenes dairy isolates to acid or salt stress and the effect of acid or salt adaptation on adherence to abiotic surfaces

During food processing, and particularly in cheese manufacturing processes, Listeria monocytogenes may be exposed routinely to environments of low pH or high salt concentration. It has been suggested that these environmental conditions may contribute to bacterial adherence to abiotic surfaces and increased resistance to disinfection. In this study strains isolated from the environment of artisanal cheese-making dairies were used to investigate the behaviour of L. monocytogenes in response to acid and salt stress and clear differences between strains was observed. In planktonic culture, strains varied in resistance to low pH or high NaCl concentration and in the occurrence of an adaptive response to moderate acid or NaCl. There was dislocation in responses to salt and acid. Strains resistant, or adaptive, to acid were not resistant or adaptive to NaCl. The reverse also was observed. Exposure to moderate acid did not promote adherence to polystyrene but survival, at low pH or high NaCl concentration, of cells adherent to stainless steel was increased, even for strains that had no adaptive response planktonically, but the detail of these observations varied between strains. In contrast to acid adaptation, with some strains salt adaptation enhanced adherence of L. monocytogenes to polystyrene but this was not true for all strains. For some strains salt- or acid adaptation may enhance the survival of sessile cells exposed to hypochlorite disinfection.     

Studies on the anthocyanin profile of <Emphasis Type="Italic">Vitis Vinifera</Emphasis> intraspecific hybrids (Monastrell × Cabernet Sauvignon)

A collection of 143 plants arising from crosses from Monastrell × Cabernet Sauvignon is available in our orchards. A 3-year study enabled us to identify the differences between the different plants. In 2005, we had studied the anthocyanin profile and color characteristics of the most promising hybrids as a part of a project to select those plants showing the most interesting enological characteristics. Differences in the anthocyanin profile were observed between Monastrell and Cabernet Sauvignon grapes, the hybrids showing, in general, an anthocyanin profile intermediate between these two varieties, although closer to that of Cabernet Sauvignon grapes. To the best of our knowledge, this is the first work to study how the anthocyanin profile of two premium Vitis vinifera varieties is inherited by the resulting hybrid plants. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Passivation of steel surface: An atomistic modeling approach aided with X-ray analyses

Using a quantum mechanics-based atomistic modeling approach and X-ray analyses, we explored the oxidation process of steel surface in a typical ambient condition. The growth of iron oxides on steel surface was found to be highly dependent on the thermodynamics and availability of reactants. Three oxidation stages were identified before the formation of a high-density triplex structure on steel surface, after which the oxidation of iron atoms progressed at a significantly reduced speed. Results from this atomistic study can be expected to improve the understanding of the passivation and depassivation of steel surface toward an effective control of iron corrosion.     

Sunflower Oil but Not Fish Oil Resembles Positive Effects of Virgin Olive Oil on Aged Pancreas after Life-Long Coenzyme Q Addition

An adequate pancreatic structure is necessary for optimal organ function. Structural changes are critical in the development of age-related pancreatic disorders. In this context, it has been reported that different pancreatic compartments from rats were affected according to the fat composition consumed. Since there is a close relationship between mitochondria, oxidative stress and aging, an experimental approach has been developed to gain more insight into this process in the pancreas. A low dosage of coenzyme Q was administered life-long in rats in order to try to prevent pancreatic aging-related alterations associated to some dietary fat sources. According to that, three groups of rats were fed normocaloric diets containing Coenzyme Q (CoQ) for two years, where virgin olive, sunflower, or fish oil was included as unique fat source. Pancreatic samples for microscopy and blood samples were collected at the moment of euthanasia. The main finding is that CoQ supplementation gives different results according to fat used in diet. When sunflower oil was the main fat in the diet, CoQ supplementation seems to improve endocrine pancreas structure and in particular β-cell mass resembling positive effects of virgin olive oil. Conversely, CoQ intake does not seem to improve the structural alterations of exocrine compartment previously observed in fish oil fed rats. Therefore CoQ may improve pancreatic alterations associated to the chronic intake of some dietary fat sources.     

The effects of consuming probiotic‐fermented milk on the immune system: A review of scientific evidence

Fermented dairy products are commonly used as the most efficient delivery vehicle for probiotics. These foods are well known for promoting the positive health benefits of consuming probiotics. Among their beneficial effects, their immunomodulatory properties have attracted a great deal of interest in recent years. Reports, both in vitro and in vivo, on the beneficial effects of consuming fermented milks containing probiotics have demonstrated the enhancement of various parameters in animal (e.g. rats and mice) and human immune systems, such as the production of cytokines and mediators by antigen‐presenting cells and cellular markers for different cell populations. Hence, the purpose of this review was to provide an overview of the scientific literature concerning the potential of probiotic‐fermented milks to influence the host's immune system, thereby modulating the immune response in a positive fashion.     

Comparison of five in vitro digestion models to study the bioaccessibility of soil contaminants

Soil ingestion can be a major exposure route for humans to many immobile soil contaminants. Exposure to soil contaminants can be overestimated if oral bioavailability is not taken into account. Several in vitro digestion models simulating the human gastrointestinal tract have been developed to assess mobilization of contaminants from soil during digestion, i.e., bioaccessibility. Bioaccessibility is a crucial step in controlling the oral bioavailability for soil contaminants. To what extent in vitro determination of bioaccessibility is method dependent has, until now, not been studied. This paper describes a multi-laboratory comparison and evaluation of five in vitro digestion models. Their experimental design and the results of a round robin evaluation of three soils, each contaminated with arsenic, cadmium, and lead, are presented and discussed. A wide range of bioaccessibility values were found for the three soils: for As 6-95%, 1-19%, and 10-59%; for Cd 7-92%, 5-92%, and 6-99%; and for Pb 4-91%, 1-56%, and 3-90%. Bioaccessibility in many cases is less than 50%, indicating that a reduction of bioavailability can have implications for health risk assessment. Although the experimental designs of the different digestion systems are distinct, the main differences in test results of bioaccessibility can be explained on the basis of the applied gastric pH. High values are typically observed for a simple gastric method, which measures bioaccessibility in the gastric compartment at low pHs of 1.5. Other methods that also apply a low gastric pH, and include intestinal conditions, produce lower bioaccessibility values. The lowest bioaccessibility values are observed for a gastrointestinal method which employs a high gastric pH of 4.0.