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761.
The use of sub-surface constructed wetlands for wastewater treatment in the Czech Republic: 10 years experience 总被引:7,自引:0,他引:7
Wetlands have been intensively studied in the Czech Republic for more than 30 years, but the first full-scale constructed wetland (CW) for wastewater treatment was built in the Czech Republic in 1989. By the end of 1999, about 100 CWs were put in operation. The majority of the systems are horizontal subsurface flow (HSF) CWs and are designed for the secondary treatment of domestic or municipal wastewater. The size of CWs ranges between 18 and 4500 m2 and between 4 and 1100 population equivalent (PE). Most frequently used filtration media are gravel and crushed rock with size fractions of 4/8 and 8/16 mm and Phragmites australis is the most commonly used plant. The treatment efficiency is high in terms of BOD5 (88.0% for vegetated beds) and suspended solids (84.3% for vegetated beds). The removal of nutrients is lower for vegetated beds, and averages 51 and 41.6% for total phosphorus and total nitrogen, respectively. 相似文献
762.
John R. Barton Andreas Schneider Johannes Jager 《The International Journal of Life Cycle Assessment》2002,7(1):11-17
Establishing BAT (Best Available Techniques) for processes subject to IPPC is a new barrier and one that processes in the
development stage need to be aware of. For multi-functional processes, the sectorial approach adopted under IPPC (Integrated
Pollution Prevention and Control) increases the potential problems. Life Cycle Assessment (LCA) is an established tool to
assist establishing BAT but is difficult to apply in its full form at the Research and Development (R&D) stage. A review of
LCA in the context of a case study, the Trefoil kiln process, concludes that it has the flexibility to cope with multi-functionality
and that use of key environmental issues and key indicators could overcome the informational gaps. Environmental burdens can
be presented appropriately provided the research identifies appropriate allocation methods. The use of LCA thinking provided
useful insight on the content of the research programme. 相似文献
763.
The modification reaction of sago starch with succinic anhydride (SA) using pyridine (PY) and/or 4-dimethyaminopyridine (DMAP) as catalyst and N,N-dimethylacetamide (DMA)/lithium chloride (LiCl) system as solvent was studied. A series of succinylated starch derivatives were prepared with a degree of substitution (DS) ranging from 0.14 to 1.54. The structure of the resulting polymers determined by means of 13C NMR spectroscopy indicated that substitution preferably occurs at the C2 and C6 hydroxyl groups. The thermal stability of the material was decreased by chemical modification. Effects of reactant molar ratio, reaction time, and the concentrations of DMAP and LiCl on the reaction efficiency are discussed. 相似文献
764.
Kamalaporn Phumpradab Shabbir H. Gheewala Masayuki Sagisaka 《The International Journal of Life Cycle Assessment》2009,14(4):354-363
Background, aim, and scope The main primary energy for electricity in Thailand is natural gas, accounting for 73% of the grid mix. Electricity generation
from natural gas combustion is associated with substantial air emissions. The two technologies currently used in Thailand,
thermal and combined cycle power plant, have been evaluated for the potential environmental impacts in a “cradle-to-grid”
study according to the life cycle assessment (LCA) method. This study evaluates the environmental impacts of each process
of the natural gas power production over the entire life cycle and compares two different power plant technologies currently
used in Thailand, namely, combined cycle and thermal.
Materials and methods LCA is used as a tool for the assessment of resource consumption and associated impacts generated from utilization of natural
gas in power production. The details follow the methodology outlined in ISO 14040. The scope of this research includes natural
gas extraction, natural gas separation, natural gas transmission, and natural gas power production. Most of the inventory
data have been collected from Thailand, except for the upstream of fuel oil and fuel transmission, which have been computed
from Greenhouse gases, Regulated Emissions, and Energy use in Transportation version 1.7 and Global Emission Model for Integrated
Systems version 4.3. The impact categories considered are global warming, acidification, photochemical ozone formation, and
nutrient enrichment potential (NEP).
Results The comparison reveals that the combined cycle power plant, which has a higher efficiency, performs better than the thermal
power plant for global warming potential (GWP), acidification potential (ACP), and photochemical ozone formation potential
(POCP), but not for NEP where the thermal power plant is preferable.
Discussion For the thermal power plant, the most significant environmental impacts are from power production followed by upstream of
fuel oil, natural gas extraction, separation, and transportation. For the combined cycle power plant, the most significant
environmental impacts are from power production followed by natural gas extraction, separation, and transportation. The significant
difference between the two types of power production is mainly from the combustion process and feedstock in power plant.
Conclusions The thermal power plant uses a mix of natural gas (56% by energy content) and fuel oil (44% by energy content); whereas, the
combined cycle power plant operates primarily on natural gas. The largest contribution to GWP, ACP, and NEP is from power
production for both thermal as well as combined cycle power plants. The POCP for the thermal power plant is also from power
production; whereas, for combined cycle power plant, it is mainly from transmission of natural gas.
Recommendations and perspectives In this research, we have examined the environmental impact of electricity generation technology between thermal and combined
cycle natural gas power plants. This is the overview of the whole life cycle of natural gas power plant, which will help in
decision making. The results of this study will be useful for future power plants as natural gas is the major feedstock being
promoted in Thailand for power production. Also, these results will be used in further research for comparison with other
feedstocks and power production technologies. 相似文献
765.
Md. Khurshid Alam Khan Utpal Das Md. Hamidur Rahaman Md. Imtaiyaz Hassan A. Srinivasan Tej P. Singh Faizan Ahmad 《Journal of biological inorganic chemistry》2009,14(5):751-760
Amino acid sequences of seven subfamilies of cytochromes c show that other than heme binding residues there are only four positions which are conserved in all subfamilies: Gly/Ala6,
Phe/Tyr10, Leu/Val/Phe94, and Tyr/Trp/Phe97. These residues are 90% conserved in all sequences reported and are also considered
to be involved in a common folding nucleus. To determine the importance of conserved interactions offered by the side chain
of Leu94, we made an L94G mutant of horse cytochrome c. Characterization of this mutant by the far-UV, near-UV, and Soret circular dichroism, intrinsic and 1-Anilino-8-naphthalene
sulfonate fluorescence, and dynamic light scattering measurements led to the conclusion that the L94G mutant has all the common
structural characteristics of a molten globule at pH 6.0 and 25 °C. NaCl induces a cooperative transition between the acid-denatured
state and a state of L94G having all the common structural characteristics of a pre-molten-globule state at pH 2 and 25 °C.
Thermal denaturation studies showed that the midpoint of denaturation of the mutant is 28 °C less than that of the wild-type
protein. Interestingly, the structure analysis using the coordinates given in the Protein Data Bank (1hrc) also suggested
that the L94G mutant would be less stable than the wild-type protein. 相似文献
766.
This paper studies the energy valorization of sewage sludge using a batch fry–drying process. Drying processes was carried out by emerging the cylindrical samples of the sewage sludge in the preheated recycled cooking oil. Experimental frying curves for different conditions were determined. Calorific values for the fried sewage sludge were hence determined to be around 24 MJ kg−1, showing the auto-combustion potential of the fried sludge. A one-dimensional model allowing for the prediction of the water removal during frying was developed. Another water replacement model for oil intake in the fried sewage sludge was also developed. Typical frying curves were obtained and validated against the experimental data. 相似文献
767.
Maja Berden-Zrimec Jasmina Kožar Logar Alexis Zrimec Luka Drinovec Mladen Franko Alenka Malej 《Central European Journal of Biology》2009,4(3):313-320
A new approach to the studies of the microalgal cell lysis by utilizing a combination of two complementary methods is presented.
Delayed fluorescence (DF) is a measure of the living algal biomass, detecting only cells with active photosynthesis. Thermal
lens spectrometry (TLS) detects the total pigment amount released from lysed cells. Both methods select for photosynthetic
organisms, reducing possible background from other sources (e.g. heterotrophic bacteria, zooplankton, and abiotic substances).
The DF/TLS method was tested with a laboratory Skeletonema costatum culture exposed to a geometric dilution series of the
lysing factor poly- APS. The exposure resulted in similar EC50 values for DF intensity, TLS and dissolved esterase activity of 0.8±0.2, 1.77±0.35, and 1.25±0.1 mg poly-APS l−1, respectively. The combined DF/TLS method enabled a rapid evaluation of the living vs. dead cells without any sample pretreatment
or manipulation. 相似文献
768.
Early Ilerdian (Early Eocene, Shallow Benthic Zones 5 and 6) carbonate systems of the Pyrenees shelf were deposited after a time of severe climatic (‘Paleocene–Eocene Thermal Maximum, PETM’) and phylogenetic (‘Larger Foraminifer Turnover’) changes. They reflect the radiation of nummulitid, alveolinid, and orbitolitid larger foraminifera after remarkable biotic changes at the end of the Paleocene, and announce their subsequent flourishing in the Middle Eocene.A paleoenvironmental model for tropical carbonate environments of this particular time interval is provided herein. During the Early Ilerdian, the inner and middle ramp deposits from Minerve, Campo and Serraduy revealed the end-member of a tropical carbonate factory with carbonate production dominated by the end-members of biotically (photo-autotrophic skeletal) controlled and biotically induced carbonate precipitation. Inner platform environments are dominated by alveolinids and in part by orbitolitids, middle platform environments are dominated by nummulitids. Corals are present, but they do not form reefs, which is a typical feature for the Eocene. Nummulite shoal complexes, which are well-known from the Middle Eocene are also absent during the studied Early Ilerdian interval, which may reflect the early evolutionary stage of this group. 相似文献
769.
Amphibian populations have been declining globally for the last several decades, and climate change is often regarded as one of the most important factors driving these declines. Amphibians are particularly sensitive to climatic changes due to their physiological, ecological and behavioral characteristics. Here we performed a laboratory experiment to investigate how temperature affects ovipositing females, eggs and hatchlings in two syntopic populations of alpine newts, Ichthyosaura alpestris, and smooth newts, Lissotriton vulgaris. Female newts were assigned to two different oviposition temperatures (11 °C and 14 °C) for the duration of their oviposition period. Deposited eggs were equally divided and assigned to three different incubation temperatures (11 °C, 14 °C and 17 °C). We hypothesized that oviposition will be affected by temperature, that the combination of different oviposition and incubation temperatures may have an effect on embryonic and hatchling traits (embryonic mortality, days to hatch and hatchling length), and that these effects might differ between the two newt species. Temperature affected the number of deposited eggs in smooth newts, but not in alpine newts. Larval hatching success was not affected by oviposition or incubation temperature. Temperature effects on hatching time and hatchling length differed between the two species. These results suggest that temperature changes may have disparate effects on amphibian reproduction, even in syntopic taxa. 相似文献
770.
A thermal therapy for cancer in skin tissue is numerically investigated using three bioheat conduction models, namely Pennes, thermal wave and dual-phase lag models. A laser is applied at the surface of the skin for cancer ablation, and the temperature and thermal damage distributions are predicted using the three bioheat models and two different modeling approaches of the laser effect. The first one is a prescribed surface heat flux, in which the tissue is assumed to be highly absorbent, while the second approach is a volumetric heat source, which is reasonable if the scattering and absorption skin effects are of similar magnitude. The finite volume method is applied to solve the governing bioheat equation. A parametric study is carried out to ascertain the effects of the thermophysical properties of the cancer on the thermal damage. The temperature distributions predicted by the three models exhibit significant differences, even though the temperature distributions are similar when the laser is turned off. The type of bioheat model has more influence on the predicted thermal damage than the type of modeling approach used for the laser. The phase lags of heat flux and temperature gradient have an important influence on the results, as well as the thermal conductivity of the cancer. In contrast, the uncertainty in the specific heat and blood perfusion rate has a minor influence on the thermal damage. 相似文献