Monitoring of human enteric viruses and coliform bacteria in waters after urban flood in Jakarta, Indonesia.

Floodwaters in Kampung Melayu village, Jakarta, Indonesia, as well as river water and consumable water (including groundwater and tap water) samples in flooded and non-flooded areas, were quantitatively analysed to assess occurrence of viruses and total coliforms and E. coli as bacterial indicators after flooding event. High numbers of enterovirus, hepatitis A virus, norovirus (G1, G2) and adenovirus were detected at high concentration in floodwaters and waters sampled from Ciliwung River which runs across metropolitan Jakarta and is used widely for agriculture and domestic purposes by poor residents. One out of three groundwater wells in the flooded area was contaminated with all viruses tested while no viruses were found in groundwater samples in non-flooded areas and tap water samples. The results revealed that human enteric viruses, especially hepatitis A virus and adenovirus, were prevalent in Jakarta, Indonesia. This study suggested that flooding posed a higher risk of viral infection to the people through contamination of drinking water sources or direct contact with floodwaters.     

Dynamical modelling of an activated sludge system of a petrochemical plant operating at high temperatures.

The Mexican petrochemical industry, Morelos S.A. de C.V., is one of the biggest and more important petroleum industries in Mexico and Latin America. It has an activated sludge system to treat its wastewater flow, which is approximately 7,000 m3/d. The wastewater contains volatile organic carbon substances classified as toxics. The old surface aeration system was changed for fine bubble diffusers; however, one major drawback of the new aeration system is that the temperature in the bioreactor has increased due to the compression of the air, which at the compressor exit reaches 85 degrees C. This effect results in the temperature in the bioreactor attaining 32 degrees C during the fall, whereas in the spring and summer, the bioreactor temperature reaches higher values than 40 degrees C. The high temperatures reduce the microorganism activity and cause a higher volatilisation rate of volatile compounds, among other effects, which affect the performance of the biological treatment. This work was performed to obtain a better modelling of the wastewater treatment from the petrochemical industry. The model describes the effect of the temperature on the performance of the biological treatment. The model was obtained from tests that were carried out in laboratory reactors with 14 L capacity, which were operated at different temperatures (from 30 to 45 degrees C), with the same wastewater and conditions as the actual system.     

Boosting nitrification by membrane-attached biofilm.

Nitrification is a key step for reliable biological nitrogen removal. In order to enhance nitrification in the activated sludge (AS) process, membrane-attached biofilm (MAB) was incorporated in a conventional activated sludge tank. Simultaneous organic carbon removal and nitrification of the MAB incorporated activated sludge (AS + MAB) process was investigated with continuous wastewater treatment. The effluent TOC concentration of AS and the AS + MAB processes were about 6.3 mg/L and 7.9 mg/L, respectively. The TOC removal efficiency of both AS and AS + MAB were above 95% during the wastewater treatment, indicating excellent organic carbon removal performance in both processes. Little nitrification occurred in the AS process. On the contrary, successful nitrification was obtained with the AS + MAB process with nitrification efficiency of about 90%. The volumetric and surface nitrification rates were about 0.14 g/Ld and 6.5 g/m2d, respectively. The results clearly demonstrated that nitrification in the conventional AS process was boosted by MAB. Furthermore, the microfaunal population in the AS + MAB process was different from that in the AS process. The high concentration of rotifers in the AS + MAB process was expected to decrease the generation of excess sludge in the process.     

Nanolayered lightweight flexible shields with multidirectional optical transparency

New nanolayered coatings are designed and deposited on flexible plastic substrate having the thickness of 100 /spl mu/m, in order to realize lightweight ultrathin transparent shielding foils. The structure of the coating is optimized considering three figures of merit: the average transmittance in the visible range for normal incidence, the normalized average transmittance for oblique incidence at 550 nm, and the transmittance quality factor. The nanotechnology exploited for the deposition of the transparent metals is the dual ion beam sputtering. Tests of durability, optical transmission, and shielding effectiveness demonstrate that the film has a high adhesion under mechanical solicitation, high resistance against aging, peak transmittance in the visible range higher than 70%, omnidirectional properties in the range 0/spl deg/-60/spl deg/, and shielding effectiveness of 40 dB up to 6 GHz.     

Effect of temperature and cyclic heating on the structure and strength of glass textolite

The article established the regularities of change of the physicomechanical characteristics and strength of glass textolites in single and repeated thermal loading. It shows that under multiple loading the intense loss of strength of the investigated materials is due to increased porosity on account of the large number of microcracks appearing in the structure. A correlation is obtained between the elastic and strength characteristics and porosity in dependence on the temperature of multiple heating which in the first approximation is described by a polynomial of second degree with respect to temperature, multiplied by the reciprocal of porosity.Translated from Problemy Prochnosti, No. 6, pp. 53–58, June, 1991.     

Comfort limits for asymmetric thermal radiation

Groups of 32 and 16 subjects of both sexes were exposed in an environmental chamber to radiant asymmetry caused by a cool wall, a warm wall, and a cool ceiling. Each subject was tested individually while seated and clothed at 0.6 clo. During each 3.5-hour experiment the subject was exposed to six radiant temperature asymmetries. He was asked whether and where he experienced any local cool or warm sensation, and whether it was felt to be uncomfortable. During the entire experiment he was kept thermally neutral by changing the air temperature according to his wishes.For cool walls, warm walls, and cool ceilings curves have been established showing the percentage of dissatisfied subjects as a function of the radiant asymmetry. Radiant asymmetry at a warm wall caused less discomfort than a cool wall. A cool ceiling caused less discomfort than a warm ceiling. Accepting that 5% of the subjects may feel uncomfortable. a radiant temperature asymmetry of 10°C is allowable at a cool wall, 23°C at a warm wall, and 14°C under a cool ceiling. A previous study showed that 4°C is allowable under a warm ceiling. Radiant asymmetry had no significant impact on the operative temperatures preferred by the subjects. No significant differences were observed between the responses of men and women exposed to radiant asymmetry.