Coupling of sequencing batch reactor and mesh filtration: operational parameters and wastewater treatment performance

Wastewater treatment performance of the combined process of sequencing batch reactor (SBR) and mesh filtration bio-reactor was investigated with a synthetic wastewater. In this system, the filtration was performed only by the water level difference between the reactor and the effluent port, with the help of a sludge layer which accumulated on the mesh filter.

A half volume of the mixed liquor was filtrated for ca. 1 h, and the filtration time was not affected by the initial pressure within the range of 0.5–2.0 m-H₂O. Since the mesh filter could effectively reject the biomasses in the reactor, the effluents contained SS of less than 1 mg/L and BOD of less than 10 mg/L under continuous or intermittent aeration conditions. Nitrogen was also removed effectively with the adjustment of aeration time under the intermittent aeration conditions.

The results obtained in this work indicate that mesh filtration could be effectively combined with SBR and improve the performance of SBR.

In addition, it was shown that the performance of the mesh filtration such as filtration time and solids separation was influenced significantly by the saccharide content in the exocellular polymer of the activated sludge.     

Evaluation of some halogen biocides using a microbial biofilm system

A simple method for the formation of microbial biofilms of three species, Pseudomonas fluorescens, Pseudomonas aeruginosa, and Klebsiella pneumoniae, on a small glass slide was established, and its suitability for evaluation of disinfectant efficacy was examined. The biofilms formed were observed in situ by confocal laser scanning microscopy (CLSM). Using the biofilms established, biocidal efficacy of several halogen biocides, such as hypochlorite (HOCl), bromochlorodimethylhydantoin (Br, Cl-DMH), ammonia monochloramine (NH2Cl), a stabilized hypobromite biocide named STABREX, and a mixed solution of NH4Br and HOCl, was evaluated. The formation of NHBrCl in the mixed solution was indicated by UV spectra analysis. Biofilm cells were more resistant to these biocides than planktonic cells and the extent of resistance varied with the biocide tested. Among the biocides tested, the biocidal potency of HOCl was the most susceptible to the change brought about by biofilm formation. By CLSM observation, differences in biofilm conformation were revealed between the microbial species. The efficacy of the biocide tested varied with the structure of biofilms formed. The assay method developed in the present study would be useful for further investigation on biofilm disinfection.     

Organic air pollutants inside and outside residences in Shimizu, Japan: levels, sources and risks

Concentrations of 38 organic air pollutants including aromatic hydrocarbons (AHCs), carbonyl compounds (CCs), volatile organic halogenated compounds (VOHCs), and organophosphorus compounds (OPCs) were measured in indoor and outdoor air in an industrial city, Shimizu, Shizuoka Prefecture, Japan. Levels of pollutants tended to be higher indoors than outdoors in both summer and winter except for benzene, carbon tetrachloride, trichloroethylene, tetrachloroethylene, and dichlorvos (DDVP). This trend was especially pronounced for CCs such as formaldehyde and acetaldehyde. For the organic air pollutants, the concentrations of AHCs and VOHCs substantially increased in winter, but not those of CCs and OPCs; the trends were similar for both indoors and outdoors. We investigated possible indoor sources of pollutants statistically. Multiple regression analysis of corresponding indoor and outdoor concentrations and the responses to our questionnaire showed that indoor concentrations of certain AHCs were significantly affected by their outdoor concentrations and cigarette smoking. For formaldehyde, indoor concentrations were significantly affected by house age and the presence of carpet or pets. For p-dichlorobenzene (pDCB), the concentrations in bedroom trended to be higher than those in other indoors and outdoors, suggested that mothballs for clothes present in bedrooms are the principal indoor source of pDCB. We compared indoor and outdoor pollutant concentrations to acceptable risk limits for 11 organic air pollutants. In indoors without smoking samples, the geometric mean concentrations of benzene, formaldehyde, acetaldehyde, carbon tetrachloride, pDCB, and DDVP exceeded the equivalent concentration representing the upper bound of one-in-one-hundred-thousand (1x10(-5)) excess risk over a lifetime of exposure.     

Anaerobic treatment of municipal wastewater at ambient temperature: Analysis of archaeal community structure and recovery of dissolved methane

Anaerobic treatment is an attractive option for the biological treatment of municipal wastewater. In this study, municipal wastewater was anaerobically treated with a bench-scale upflow anaerobic sludge blanket (UASB) reactor at temperatures from 6 to 31 °C for 18 months to investigate total chemical oxygen demand (COD) removal efficiency, archaeal community structure, and dissolved methane (D-CH₄) recovery efficiency. The COD removal efficiency was more than 50% in summer and below 40% in winter with no evolution of biogas. Analysis of the archaeal community structures of the granular sludge from the UASB using 16S rRNA gene-cloning indicated that after microorganisms had adapted to low temperatures, the archaeal community had a lower diversity and the relative abundance of acetoclastic methanogens decreased together with an increase in hydrogenotrophic methanogens. D-CH₄, which was detected in the UASB effluent throughout the operation, could be collected with a degassing membrane. The ratio of the collection to recovery rates was 60% in summer and 100% in winter. For anaerobic treatment of municipal wastewater at lower temperatures, hydrogenotrophic methanogens play an important role in COD removal and D-CH₄ can be collected to reduce greenhouse gas emissions and avoid wastage of energy resources.     

Deformation and recrystallization textures of copper single crystals and bicrystals

Recrystallization textures in rolled copper specimens have been investigated so as to elucidate the mechanisms of cube texture formation. The specimens are single crystals with the orientations corresponding to the main components of the rolled textures, such as {112}111,{110}112, etc. and bicrystals consisting of such oriented crystals. The cube texture was not observed in any single crystal specimens, but observed in only two bicrystal specimens with {112}/111{100}001 and {110}112/{100}001 orientations. The formation of cube texture seems to require the existence of a cube oriented region in the deformed state, and the favourable oriented matrix to allow the growth of such nuclei.     

Determination of refractive index and absorption coefficient of iron- oxide-bearing slags

The refractive index and absorption coefficient of amorphous Fe₂O₃-SiO₂-CaO-Al₂O₃ slags have been determined at room temperature as functions of the basicity of [mass pct CaO]/[mass pct SiO₂] and the Fe₂O₃ concentration. The refractive index has been measured by an ellipsometer at 546 nm, and the absorption coefficient has been determined from transmittance measured by a spectrophotometer in the wavelength range of 350 to 1000 nm. The refractive index increases with increasing basicity of [CaO]/[SiO₂] and the Fe₂O₃ concentration. On the other hand, with decreasing basicity of [CaO]/[SiO₂], the absorption coefficient is increased in the near-infrared region, and the absorption edge by the charge transfer band is shifted to a shorter wavelength. With increasing Fe₂O₃ concentration, the absorption coefficient is increased in the measured wavelength range, and the absorption edge by the charge transfer band is shifted to a longer wavelength. These dependences of refractive index and absorption coefficient on the basicity and the Fe₂O₃ concentration are discussed.     

Disposition of the selective alpha1A-adrenoceptor antagonist tamsulosin in humans: comparison with data from interspecies scaling

Tamsulosin-HCl is an alpha1A-adrenoceptor antagonist that is mainly eliminated by metabolism in animals and humans and is highly bound to alpha1-acid glycoprotein in blood plasma. The disposition of the compound (0.4 mg as modified-release granules in a capsule) was determined in male volunteers, using intravenous (iv) infusion of tamsulosin-HCl (0.125 mg over 4 h) as reference treatment for the assessment of absolute oral bioavailability. Disposition parameters of iv tamsulosin in humans was compared with data predicted from animal data by interspecies scaling techniques. Levels after iv dosing in humans showed a biexponential decline, with mean half-lives (+/-SD) of 1.2 +/- 0.6 and 6.8 +/- 3.5 h, respectively. The mean systemic clearance (+/-SD) was low (viz., 48 +/- 24 mL/min). The mean volume of distribution (+/-SD) was rather small (21 +/- 6 L), and was estimated at 16 +/- 4 L in the steady state. The mean absolute oral bioavailability (+/-SD) was approximated at 100 +/- 19%. Systemic clearance in humans was poorly predictable from a logarithmic clearance versus body weight relation of rat, rabbit, and dog data. The prediction improved dramatically (accuracy 213%) when scaling was done with systemic clearance values of unbound drug, and it improved further (accuracy 59%) with the product of unbound clearance and maximum life-span potential. Also, the prediction of volume of distribution improved dramatically (accuracy 81%) after correction for differences in extent of protein binding between species. The terminal disposition half-life of 7.0 h, as predicted after integrating maximum life-span potential and protein binding in scaling of clearance, was very close to the value of 6.8 h established experimentally in humans. The present results with tamsulosin underline the importance of correction for extent of protein binding in allometric scaling of clearance and distribution volume.     

Apolipoprotein E epsilon 4 allele distribution in Wernicke-Korsakoff syndrome with or without global intellectual deficits

Recent genetic studies show that the apolipoprotein E (ApoE) epsilon 4 allele is a risk factor for Alzheimer's disease (AD). Whether this allele is associated with other dementing diseases is the next important question. The information could provide a clue to the pathogenetic role of ApoE. In the present study, patients with Wernicke-Korsakoff syndrome (WKS) of alcoholic etiology were divided into two groups according to the severity of intellectual deficits, i.e., those of "classical" Korsakoff patients with preserved intellectual function other than amnesia and those with global intellectual deficits. Genotyping showed that the frequency of ApoE epsilon 4 allele was significantly higher in the patients with global deficits, suggesting the involvement of this allele in the intellectual decline of WKS. In contrast, distributions of other two markers, alpha 1-antichymotrypsin and presenilin-1, did not differ between the two groups. These results added further support to the notion that the consequence of acute insult to the brain is influenced by the ApoE genotype, and suggested ApoE's role in the development of a certain group of "alcoholic dementia."     

Thermodynamics of iron oxide in Fe x O-dilute CaO+Al2O3+Fe x O fluxes at 1873 K

The distribution of iron between Fe _x O-dilute CaO+Al₂O₃+Fe _x O fluxes and Pt+Fe alloys, as well as the redox equilibrium of iron ions in these fluxes, was experimentally investigated in pressure-controlled CO₂/CO gas at 1873 K. Total iron content in flux (pct Fe ^T ) and the ratio of (pct Fe²⁺) to (pct Fe ^T ) in fluxes with constant can be related to the activity of iron, α _Fe, and the partial pressure of oxygen, a _Fe, using the following equation:

Crystal structure of DNA photolyase from Anacystis nidulans

Micronutrient deficiencies probably have few direct effects on the functioning of immune cells. The main effect appears to be a reduction in cell mass that may indirectly affect immune cell function, particularly where T helper cell numbers are reduced. Results of many human studies are contradictory. Some of this contradiction may be accounted for by the fact that disease may lower concentrations of micronutrients in plasma that may be misinterpreted as deficiency. Low plasma vitamin A concentrations however appear to impair immune responsiveness and have deleterious effects on membrane integrity and mucosal function. Zinc may have similar effects on gut integrity and appears to be particularly useful in the treatment of acute diarrhoea. Low concentrations of other nutrients such as ascorbate and iron, may not necessarily impair immune function. Low plasma ascorbate may assist the removal of iron from plasma and low iron concentrations appear to increase the cytotoxicity of macrophages.