خيارات البحث
النتائج 1 - 8 من 8
Using elevated temperatures to enhance in-situ remediation in low-permeable soils and groundwater
1997
Heron, G.
PLATIN (PLant-ATmosphere INteraction) II: co-occurrence of high ambient ozone concentrations and factors limiting plant absorbed dose
1997
Grunhage, L. | Jager, H.J. | Haenel, H.D. | Hanewald, K. | Krupa, S. (Institute for Plant Ecology, University of Giessen, Heinrich-Buff-Ring 38, D-35392 Giessen, Germany)
Composting of spent pig litter at different seasonal temperatures in subtropical climate
1997
Tiquia, S.M. | Tam, N.F.Y. | Hodgkiss, I.J. (Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China))
Major pathways for nitrogen removal in waste water stabilization ponds
1997
Lai, Patrick C. C. | Lam, Paul K. S.
A study on the factors influencing nitrogen removal in waste water stabilization ponds was undertaken in an eight-pond series in Werribee, Australia. Nitrogen species including Kjeldahl nitrogen, total ammonia nitrogen, nitrite and nitrate were monitored monthly from March 1993 to January 1994. At the same time, pH, temperature, chlorophylla content and dissolved oxygen were also recorded. Highest nitrogen removal occurred during the period with highest levels of chlorophylla content and dissolved oxygen, but the rate of nitrogen removal was not related to temperature and pH. Enhanced photosynthetic activities resulting from an increased phytoplankton abundance due to prolonged detention time caused an increase in dissolved oxygen, and created an optimum condition for nitrification to occur. In this process, ammonia was oxidized to nitrite and nitrate which were subsequently reduced to elemental nitrogen. Apart from nitrification-denitrification which was the major nitrogen removal pathway in the study system, algal uptake of ammonium, nitrate and nitrite as nutrient sources also contributed to the nitrogen removal. The role of phytoplankton and zooplankton in the treatment process in waste stabilization ponds was discussed.
اظهر المزيد [+] اقل [-]General assessment of the occurrence of keratinolytic fungi in river and marine beach sediments of catalonian waters (spain)
1997
ULFIG, K. | Guarro, J. | CANO, J. | Gené Badía, Joan | Vidal, P. | Figueras, M. J.
Sediments from 8 river mouths of the Catalonian coast (Spain) were examined for keratinolytic fungi. Out of 1250 river and marine samples examined, 499 (39.9%) were positive for these fungi. Aphanoascus fulvescens (anamorph + teleomorph), Chrysosporium keratinophilum, Ch. tropicum, Ch. an. of Arthroderma curreyi, Ch. pannicola, Ch. europae and Ch. indicum were the predominant species in the sediments. River samples were rich in keratinolytic fungi, whereas in marine beach sediments they occurred sporadically. The results of a preliminary experiment demonstrated that, marine water exerted a dramatical impact on river keratinolytic fungi causing their total or near-total elimination. The qualitative and quantitative compositions of river keratinolytic mycoflora depended on the degree of water contamination with sewage and on natural factors (mainly temperature). The keratinolytic mycoflora of two rivers was possibly altered dramatically by water contaminants, including poisons of industrial origin, and marine salinity. The problem of public health risk resulting from the distribution of keratinolytic fungi within the highly-frequented recreational waters is discussed.
اظهر المزيد [+] اقل [-]The seasonal changes of keratinolytic fungi in sediments of Catalonian Rivers (Spain)
1997
Ulfig, K. | Łukasik, W. | Guarro, J. | Cano, J. | Gené Badía, Joan | Vidal, P. | Figueras, M. J.
The Catalonian river sediments were found to be rich in keratinolytic fungi. The keratinolytic fungal populations showed clear seasonal changes in the river sediments. The main factors ‘regulating’ these populations in such habitat were temperature, dissolved oxygen concentration, pH, ammonium, nitrates, total fungal number, BOD₅, water poisons (cyanides, detergents, phenols), salinity and, presumably, strong insolation associated with low water levels. The last was probably of special importance in the deterioration of the fungal populations in the spring/summer season. A toxic effect on keratinolytic fungi in sediments was observed.Chrysosporium keratinophilum was found to be most resistant to industrial contaminants and salinity. Therefore, this species could be used as an indicator of water pollution.
اظهر المزيد [+] اقل [-]Zero test emissions of sulphur dioxide from large coal under staged fluidized bed combustion
1997
Khan, W. Z. | Gibbs, B. M.
This paper reports the emissions of SO₂ from large coal under staged combustion without any additive. A stainless steel combustor, 2 m high and 0.3×0.3 m in cross section was used. Fluidizing air was supplied through a multihole distributor. An adjustable secondary air injector was used along the vertical axis of the combustor to introduce secondary air in the freeboard. From 0–40% of total air was injected in the freeboard above the bed. The experiments were carried out at fluidizing velocities of 1–2 m s⁻¹, bed temperatures of 1103–1153°K, 20–40% excess air, and bed particle sizes of 665μm. Bed temperature and level of air staging had the most significant effect on SO₂ emissions.
اظهر المزيد [+] اقل [-]Microbial phenol degradation of organic compounds in natural systems: Temperature-inhibition relationships
1997
Eismann, Frank | Kuschek, Peter | Stottmeister, Ulrich
The combined influence of high phenol concentrations and low temperatures on aerobic and anaerobic phenol degradation kinetics was investigated in microbial enrichment cultures to evaluate temperature-inhibition relationships with respect to the ambient conditions in polluted habitats. The inhibition of microbial phenol degradation by excess substrate was found to be temperature-dependent. Substrate inhibition was intensified when temperatures were lower. This results in an elevated temperature sensitivity of phenol degradation at inhibitory substrate concentrations.The synergistic amplification of substrate inhibition at low temperatures may help to explain the limited self-purification potential of contaminated habitats such as soils, sediments and groundwater aquifers where high pollutant concentrations and low temperatures prevail.
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