فهرست مطالب

Environmental Health Science and Engineering - Volume:3 Issue:4, 2007
  • Volume:3 Issue:4, 2007
  • 80 صفحه،
  • تاریخ انتشار: 1385/10/20
  • تعداد عناوین: 10
|
  • N. W. Chan Page 223
    Malaysia and Thailand are tropical countries relatively rich in water resources, but both suffer numerous water problems, chief of which is excessive domestic wastage. A lop-sided approach focusing on water supply management and neglecting water demand management have caused water problems to escalate in both countries in recent decades due to population explosion, rapid urbanization, industrial expansion and climate change. As the total quantity of available water is finite but demand increasing at geometrical rates, Malaysia and Thailand are facing water problems which have severe impacts, particularly on women. This study compares the main water issues faced by two cities, Georgetown in Malaysia and Pattaya in Thailand, both medium sized and major tourist destinations. This paper compares various water indicators for both cities, water use characteristics of consumers, and consumers’perception and willingness to pay. It also attempts to highlight the role of gender, documenting how women can manage water via water demand management in addressing water shortages. The paper concludes that water users need to be involved in a bottom-up approach in a sustained national water demand management initiative towards achieving sustainable management of water resources in both cities.
  • M. R. Monazzam Page 229
    Reactive barriers are one of the most promising and novel environmental noise barriers. In this case using Schroeder diffusers (e.g. quadratic residue diffusers) on the top surface of the T-shape barrier was shown to significantly improve the performance of absorbent T-shape barriers. The reasons behind the high performance of diffuser barriers are considered in this investigation. A question about the diffusivity behavior of Schroeder diffusers when they are utilized on the top of barrier was raised. Diffusion coefficients of a diffuser in different conditions at some receiver locations were predicted by using a 2D boundary element method. It was found that the diffusion coefficient of diffuser at the top of barrier is so small that the diffusivity of the structure is almost the same as rigid T-shape barrier. To find the barrier’s cap behavior, the total field above the top surface of profile barriers was also predicted. It was found that the lowest total energy is at the receiver side of the cap very close to the top surface,which could demonstrate the effect of top surface on absorbing the energy as wave transfers from source edge toward the receiver side of the cap. In this case the amount of minimum total energy depends on the frequency and the configuration of the top surface. A comparison between the reductions of total field at the source side of the cap with the improvements of barrier’s performance was also done. It was shown that the amount of decrease in total field compared to that of an absorbent barrier “Ref” is directly associated to the amount of improvement in the insertion loss made by the diffuser barrier compared to the “Ref” barrier in the wide area on the ground at the shadow zone. Finally it was concluded that the diffuser on the top of barrier does not act as a diffuser and a kind of similarity between the contribution of diffuser and absorbent material on the top of T-profile barrier is seen.
  • S. Sreedhar Reddy, B. Kotaiah Page 239
    The sorption of dyes from aqueous solutions on to sludge-based activated carbon have been studied and compared with commercial activated carbon. Adsorption parameters for the Langmuir and Freundlich isotherms were determined and the effects of effluent pH, adsorbent dosage, contact time and initial dye concentration were studied. A pseudo-second order kinetic model has been proposed to correlate the experimental data.
  • F. Halek, Gh. Nabi, H. Ganjidoust, M. Keyanpour, M. Mirmohammadi Page 247
    Polycyclic Aromatic Hydrocarbons are ubiquitous in the urban atmosphere and one of the most atmospheric pollutants to be identified as suspected carcinogens. The objective of this study was to compare particulate PAH profiles from several sites across Tehran. Atmospheric concentrations of Polycyclic Aromatic Hydrocarbons in Tehran were evaluated to study particulate PAH profiles in different sites. The particles size distributions were unimodal with a fine mode diameter (PM<0.49 μm). Five sites were selected in residential areas and one site in rural area for representing various situations and role of motor vehicles in producing Polycyclic Aromatic Hydrocarbons. Organics on the filter were extracted with acetonitrile and a group of 16 Polycyclic Aromatic Hydrocarbons was selected for evaluation. PAH identification was done by High Performance Liquid Chromatography. Total PAH concentration associated with particles collected on the six-stage cascade impactor stages and after-filter in different sites ranged between 0.132 to 234.3 ng/m3. The mean concentrations of Polycyclic Aromatic Hydrocarbons, collected on each stage were: 4.17 ng/m3 for PM10-7.2 μm, 5.69 ng/m3 for PM7.2 - 3 μm, 11.95 ng/m3 for PM3 - 1.5 μm, 9.18 ng/m3 for PM1.5-0.95 μm, 2.82 ng/m3 for PM0.95-0.49 μm and 47.91 ng/m3 for PM < 0.49 μm respectively.
  • M. Khosravi, S. Oryan, S.A. Haeri Rohani, K. Parivar, R. Marandi Page 255
    In the present study, it is shown that in vivo oral administration of glibenclamide (1-10 mg/kg/day), an adenosine triphosphate -sensitive potassium channel blocker, and yohimbine (1-5 mg/kg/day), an alpha 2-adrenoceptor antagonist, potently reduced glycemia in male rats. Diazoxide (1-45 mg/kg/day), a potassium channel opener, and clonidine (0.05-0.5 mg/kg/day), an alpha 2- adrenoceptor agonist, antagonized the effects of glibenclamide and yohimbine respectively. Administration of glibenclamide and yohimbine separately decreased the serum glucose levels, so it was expected that coadministration of these two drugs significantly decreased this parameter in fasted animals. It is well known that glibenclamide blocks the potassium channels and it is likely that, yohimbine also blocks these channels, but according to our data, it seems that yohimbine acts via a different binding site to that of glibenclamide. In this research it is also observed that administration of yohimbine and glibenclamide causes death in rats,, it seems that these drugs causes death in the experimental animals by lowering blood glucose level, which were the aim of this study and could be applied as a way to control the environmental health by abolishing rats.
  • E. Bazrafshan, A. H. Mahvi, S. Nasseri, A. R. Mesdaghinia, F. Vaezi, Sh. Nazmara Page 261
    The object of this study is the evaluation of cadmium removal from industrial wastewater by electrocoagulation process. For this study a glass tank in 1.56 L volume with four plate electrode was used to do experiments. The electrodes made of iron and connect to the positive and negative pole of DC power supply (bipolar mode). The tank was filled with synthetic wastewater that was containing cadmium ion in concentration 5, 50 and 500 mg/L and then it was started up. The percent of cadmium ion removal was measured at pH 3, 7 and 10 and in electric potential range of 20, 30 and 40 volts. At the end of each stage of experiment, volume of produced sludge was measured. The results obtained at different electrical potential showed that initial concentration of cadmium can effect on efficiency removal and for higher concentration of cadmium, higher electrical potential or more reaction time is needed. On the other hand, if the initial concentration increases, the time required of process should increase too. The final pH for iron electrodes was always higher than initial pH. As expected, the results showed that for a given time, the removal efficiency increased significantly with increase of current density. The highest electrical potential (40V) produced the quickest treatment with >99% cadmium reduction occurring after only 20 min. The result showed that, in this process, the use of different electrical potentials can provide a wide range of pH for doing this process and electrocoagulation process (using iron electrodes) is a reliable, safety, efficient and cost-effective method for removal of cadmium from industrial effluents, especially designed for pH =10 and voltage = 40V.
  • N. Mansouri, M. Pourmahabadian, M. Ghasemkhani Page 267
    Noise pollution is a major problem for the quality of life in urban areas. The present study was conducted to determine the noise levels of road traffic at central area of Tehran. It focused on one of the busy and crowded square along with its 7 connecting streets, which had a heavy traffic and located in the downtown of the city. Total of 115 measuring points were selected along the roads, pavements and in the shopping areas to adequately represent the different acoustically commercial situations. The measuring points were divided in to 4 site-groups namely; Street, Pavement, Shop and Barrier each with 60, 40, 10, and 5 measuring points respectively. The measurements were carried out during a full week days started on Saturday morning and end on Friday evening. The A-weighted continuous equivalent sound level values, LAeq; LA max; LA min; and the statistical levels: L1, L10, L50, L90 and L99 as well as the octave band center frequencies sound pressure levels were manually measured at each point separately. The mean values of LAeq for Street, Pavement, Shop and Barrier site groups were 78.5, 73.3, 68.7 and 70.8 dBA respectively and the overall mean of LAeq was 74.7 dBA. The statistical test (p<0.01) showed that the mean values for LAeq in all site groups as well as the overall mean value were higher than 65 dBA, which is the daytime governmentally prescribed noise limit for commercial areas. Comparing the individual measurements has also shown the 86.6% exceeded values from 65 dBA. The highest mean noise level in center frequencies upper than 1000 Hz was 71.5 dBA which was observed in the Street site group and the lowest one was 43.2 dBA in the Shop site group at 8000Hz center frequency. The corresponding values for the center frequencies lower than 1000 Hz were 78.2 and 66.1dBA at 63 and 500 Hz which were also observed in the Street and Shop site groups respectively. It can be concluded that the downtown of the city is environmentally noise polluted and the road traffic is the major source of it. Noting the noise emission standards, police control, and promoting the citizens awareness about the high level noise risk may help to relieve the noise problems in the city.
  • A. H. Javid, A. Emamzadeh, A. A. Hamidi, A. Arjmandzadeh Page 273
    Due to the close relationship between the energy and environmental problems, recovering technology and optimizing energy consumption have a major role in environment protection by minimization the atmospheric pollutants such as SOX, COX, NOX. This minimization may decrease the greenhouse effect, and the ozone layer destruction. On the other hand, optimization of Energy consumption and its recovering may minimize the water and hot oil consumption at the heat exchangers (reboilers and condensers) in petroleum distillation columns, specially. The present research has been performed about the kerosene pre-fractionation unit of one of the country''s oil refineries. This system includes two distillation columns with a simple arrangement. Considering that the distillation section consumes a great deal of energy in the chemical and petroleum industries, hence studying the ways in which we may decrease this consumption is of great importance. One of these retrofit solutions is the heat integration, which is going to be presented in this research with a different idea from the other previous methods. This method makes it possible to add a shell and tube heat exchanger for performing a part of condensation and evaporation operation which can decrease the heat duties of reboilers and one of the condensers. To this end, the distillation columns were studied in the process and then the proposed model of columns arrangement were simulated by heat integration with all input and output streams using the Aspen Plus software, version 11.1 and the Rad Frac model in this software. The result has showed itself as a save of 14.26%, 10.86% and 14.26% in energy, water and hot oil consumption, respectively. On the other hand this system will decrease emission of SO2 and CO2 to atmosphere, 28 kg/h and 837 kg/h, respectively.
  • . R. Massoudinejad, M. Manshouri, A.R. Yazdanbakhsh Page 285
    Considering the population increase in the cities and also the increase of per capita water consumption in these societies, the use of treated effluents for the green area irrigation has been taken into consideration. Human ever–increasing needs to green area in municipal societies and on the other hand the limitations in water supplies cause a new review in wastewater reuse. Also making use of treated effluents in irrigation has some limitations including clogging of the soil porosities, increasing of the chemicals and toxic substances to plants and increasing the probability of groundwater pollution. In this research, considering the indicators using recognition of the effluent’s quality, at the first stage compound samples of domestic wastewater treatment effluents of Zamyad Factory were taken. The samples were tested from the viewpoint of quality. Results showed that the indicator of Sodium Adsorption Ratio, Sodium Percentage, amounts of chloride, and electrical conductivity comparing to Food and Agriculture Organization and Department of the Environment of Iran standards were higher than the standard levels. Also parameters such as TDS, TSS, BOD, COD, anions and cations were in standard levels. Results also showed that the increase of some of the undesirable parameters was not related to the operation of wastewater treatment plant. Therefore, in order to make the standard effluent, different methods may be proposed and the most practical and economical one is dilution by using 50% mixing with raw water.
  • S. A. Mirbagheri, M. Salehi M. Page 289
    The waste of motor vehicle industries is mainly the result of washing, coloring and various stages of chassis manufacturing, which include oil, grease, dyestuff, chromium, phosphate and other pollutants. In the present research, extended aeration activated sludge biological treatment plant is being considered and evaluated, for the removal of heavy metals and pollution load from industrial wastes and sanitary wastewaters, and on the pilot scale for optimization of waste treatment method for motor vehicle industries. To accomplish the pilot experiments, the natural waste of Bahman motor vehicle factory is used. Effective factors on efficient removal of heavy metals and pollution load such as concentration of biological mass (MLVSS), COD, BOD, pH in the extended aeration activated sludge biological treatment system, in different ratios of the mixing of industrial waste to sanitary wastewater have been experimented and evaluated. The performance of the above system, in the best of conditions, removes about 90% of pollution load and 65% of heavy metals existing in the industrial wastes. After analyzing the experiments, it is concluded that the removal of heavy metals through biological methods is possible and moreover it is feasible to biologically treat the mixing of motor vehicle industries effluent and sanitary wastewater up to the ratio of one to one, if guided exactly and scientifically.