فهرست مطالب

Environmental Health Science and Engineering - Volume:2 Issue:2, 2005
  • Volume:2 Issue:2, 2005
  • تاریخ انتشار: 1384/07/20
  • تعداد عناوین: 10
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  • H. Movahedian, B. Bina, Gh Asghari Pages 1-4
    Toxicity evaluation is an important parameter in wastewater quality monitoring as it provides the complete response of test organisms to all compounds in wastewater. The water flea Daphnia magna straus is the most commonly used zooplankton in toxicological tests. The objective of this study was to evaluate the acute toxicity of effluents from different units of Isfahan Wastewater Treatment Plant (IWTP). The samples were taken from four different physical and biological units. The acute toxicity tests were determined using Daphnia magna. The immobility of Daphnia was determined after 48h. Toxicity results showed that 48h-LC50 and ATU values for raw wastewater were 30% (v/v) and 3.33, respectively. It was also found that LC50 values after 48 h for preliminary, primary, and secondary effluents were 32%, 52% and 85% (v/v), respectively. The ATU values for these effluents were 3.1, 1.9, and 1.8, correspondingly. The efficiency levels of preliminary, primary, and secondary units for removal of toxicity were found as 6%, 38.9% and 8%, in that order. Overall, the present investigation indicated that toxicity removal by up to 50% might be achieved in IWPT. Based on the obtained results and regarding the improvement of water quality standards, coupled with public expectations in Iran, it is necessary to consider more stringent water quality policies for regular monitoring and toxicity assessment.
  • Ah Mahvi, G. Mardani Pages 5-11
    In many big cities, surface runoff is collected by separate collection system and is then directed to receiving water bodies. Since it washes out the materials from the surface of different lands, is known as the source of pollution. Polycyclic aromatic hydrocarbons (PAHs) are one class of carcinogenic contaminants that are commonly found in storm water runoff. In this study, phenanthrene was measured in the surface runoff of south of Tehran, capital of Iran. After identifying three main drainage channels, three sampling stations were chosen, based of the fact that all urban surface runoffs completely passed through these points and taken samples were more expected as representative of all kinds of pollutants. Surface runoff flows in three main channels from north to south of Tehran. At each month two samples were taken from each station, afterwards concerning the USEPA method, 60 samples were extracted and analyzed with High Performance Liquid Chromatography device. Results show that the average concentration of PAH in the most polluted drainage was about 9.4 µg/l. The minimum and the maximum concentrations of PAH in all of the taken samples were zero and, 15.1 µg/l, respectively. In the rainy season, the concentration of phenanthrene was the highest, because the rain washed out the pollutant from the surface of the street. In addition, the concentration of phenanthrene in the middle drainage channel was more than two others, because this station received the runoff from city center whose traffic load was high.
  • K. Naddafi, Ah Mahvi, S. Nasseri, M. Mokhtari, H. Zeraati Pages 12-16
    Recently, inexpensive technologies for drinking water supply in small communities are highly considered in developing countries. One of these technologies is the application of ceramic filters that are usually made of diatomaceous earth or clay soil. This research was carried out to determine the efficiency of clay pots (as a filter) in removing water impurities. Pilot and the related clay parts were manufactured and its efficiency in removing TDS, hardness, NO3-, color and turbidity was measured by passing water through the clay pipes. The results showed that the clay filters had not the potential to remove hardness, EC, TDS and nitrate of water. However, they showed excellent efficiency in turbidity removal (≥ 90%) and could significantly decrease the color of the water (≥ 60%).
  • Mr Shahmansouri, H. Taghipour, B. Bina, H. Movahdian Pages 17-25
    Ammonia is a colorless, toxic, reactive and corrosive gas with a sharp odor. It is irritating to the skin, eyes, nose, throat, and lungs. Ammonia gas occurs in the environment naturally and is emitted by many industries and, therefore, its control is essential. Biofiltration is a new emerging technology that is being used as a control procedure. This study evaluates the use of a mixture of compost, sludge, and pieces of PVC as biofilter media to remove ammonia gas. The study investigates the effects of parameters such as inlet concentration, accumulation time, and depth of filter media to evaluate the removal efficiency. A laboratory scale biofilter column was built and operated to investigate the removal of ammonia from a waste gas stream. The findings indicate that for inlet concentrations of 236 ppm, and ammonia loading of less than 9.86 g-NH3/m3.h at empty bed residence time of 1 min, an ammonia removal efficiency of more than 99.9% was obtained. The acclimation period of the bacteria was 10 days. The average pressure drop during measurement was 4.44 mm H2O. The study also revealed that for concentration levels of 99, 211, and 236 ppmv, biofilter media depths of 40, 80, and 120 cm will be required, respectively. The results obtained in this study indicate that the biofiltration system composed of compost in the mixture of sludge and smashed polyvinyl chloride as biofilter media is an efficient method for the removal of ammonia from waste gas streams. It is also found that the optimum depth of biofilter media depends on the inlet concentration of ammonia.
  • Mh Ehrampoush, Mh Baghiani Moghadam Pages 26-30
    The risk of unhealthy disposal of solid waste is one of the important problems in many societies, and recycling is considered as a solution for managing solid wastes. Environmental knowledge and attitude of young people (like students) appears to be crucial as their point of view ultimately plays an important role in providing solution to future environmental problems. In this study the knowledge, attitude and practice of Yazd University of Medical Sciences students in respect of disposal of solid wastes and the important factors were studied. Two hundred thirty seven students were included in this cross-sectional study, selected from 5 schools of this university. Data collected by a self administered questionnaire containing four sections, were analyzed using SPSS for Windows. The mean grade of knowledge of men and women was 13.53 and 12.38, of 20, respectively. The difference between the knowledge of males and females was significant (P< 0.016). On the whole the knowledge of the students was not appropriate. About 66% of students did not have any action in segregation and recycling of solid wastes. It is concluded that all students must take part in formal and informal education classes to promote their knowledge in this regard.
  • Effects of Operational Conditions on the Performance of Triethylamine Biofiltration
    A. Torkian, H. Keshavarzi Shirazi, A. Azimi Pages 31-40
    Nitrogen compounds such as triethylamine are odorants generally found in chemical plants and foundries in which cold-box cores are made. In this study, the efficiency of biofiltration of triethylamine (TEA) vapor was evaluated. Experiments were conducted in two 6-L biofilters arranged in three stages and packed with inoculated compost - wood chips (40:60v/v) as the filter medium. The seed inoculum was obtained from municipal activated sludge. Tests were made to compare effects of initial temperature (30±1°C, biofilter A) and (23±2 °C, biofilter B) on the performance of the biofilter. TEA elimination rate pattern was evaluated by changing loading rates (6-138 gm-3h-1 and hydraulic retention times (40-60 s) while operating at constant temperature and humidity at 50-55%. Results showed that organic loading rates (OLR) of up to 114.4 gm-3h-1 (biofilter A) and 90.56 gm-3h-1 (biofilter B) could be handled without any apparent indication of maximum elimination capacity and substrate inhibition. The elimination capacity of biofilters could reach up to 72 gm-3h-1 (biofilter A) and 61.5 gm-3h-1(biofilter B). When the loading of TEA exceeded the critical values, substrate inhibition occurred and the elimination capacity decreased. However, the requirement of keeping the pressure drop below 4 cm water gauge per meter of bed height to avoid operational problems warranted lower than maximum capacity operation. The optimal OLR values of 90±14 gm-3h-1 are suggested for hydraulic retention time value of 48 s and temperature of 30±1°C. Under these conditions, elimination capacity of 71±3 gm-3h-1and removal efficiency of 81±14% was achieved.
  • M. Shafie, Pour Motlagh, Mm Farsiabi, Hr Kamalan Pages 41-56
    The growing world economy calls for saving natural resources with sustainable development framework. This paper intends to look at the environment-energy interface (impacts on the environment stemming form the energy sector) and to propose measures for reducing this impact without trying to impede economic development. In addition, this paper estimates the amounts of energy subsidies about 20% of Gross Domestic Product (GDP) in 2019 if the conditions do not change. Meanwhile, environmental damage from air pollution has been assessed by scaling according to GDP per capita measured in purchase power parity (PPP) terms. Using this approach, the total damage from air pollution in 2001 was assessed about $7billion; equivalent to 8.4% of nominal GDP. Lacking price reform and control policies, the authors estimate that damage in Iran will grow to 10.9% of GDP by 2019. In line with difficulties of eliminating subsidies, a list of 25 measures has been analyzed, using the environmental cost-benefit analysis and based on cost-effectiveness of the policies to verify which ones would be implemented. Finally the financial effects of implementing different combinations of price reform and carrying out those policies on the state budget, damage costs and subsidies have been calculated.
  • M. Karimi, Mh Ehrampoush, M. Mirzaei, Mh Ahmadieh Pages 57-61
    Allergic diseases are prevalent in children and their prevalence and severity are different in dissimilar areas of the world. Many studies have been carried out regarding the inspection of the causative environmental factors such as air, foods and environmental allergens. In this study, using the ISAAC standardized method, the relation between asthma and allergic rhinitis symptoms with the kind of fuel consumed at homes and the frequency of lorry passing through the streets next to the houses in 3000 children aged 6-7 years and 3000 children 13-14 years was investigated. The results indicated that in the children aged 6-7 years, the prevalence of asthma and allergic rhinitis had a meaningful relation with the type of fuel consumed at homes (P<0.05), so that the less pollutant fuel resulted in less symptoms. The evidence suggested that in both age group, when there was lorry passing all day long, there were more wheezing and allergic rhinitis symptoms, and the difference was meaningful regarding allergic rhinitis (P< 0.05). The study reveals that indoor and outdoor air pollution is associated with increase in the prevalence of allergic diseases in children. Therefore, it seems that these types of air pollution can be a cause of increase of the allergic cases in childhood.
  • Sequence-Fenton Reaction for Decreasing Phenol Formation during Benzene Chemical Conversion in Aqueous Solutions
    Sb Mortazavi, A. Sabzali, A. Rezaee Pages 62-71
    Advanced oxidation processes such as Fenton reagent generates highly reactive hydroxyl free radicals to oxidize various compounds in the water and wastewater. The efficiency of different Fenton-related oxidative processes such as Fenton, solar-Fenton, UV-Fenton and Fenton reactions in different batch reactors was examined using benzene as pollutant in aqueous solutions. A batch study was conducted to optimize parameters like pH, hydrogen peroxide concentration, temperature, reaction time and ferrous ion concentration governing the Fenton process. The concentrations of produced phenol were measured at the end of the reactions. The role of sequence reaction was tested for decreasing phenol formation during benzene conversion. At optimum conditions, different Fenton-related processes were compared for the degradation of benzene. Increased degradation efficiency was observed in photo-Fenton processes as compared to conventional Fenton process. The formation of phenol in Fenton reaction depended on reaction time, sequence in reaction, purity of hydrogen peroxide and other compounds such as alcohols that contributed into the reaction. In the Fenton process, carboxylic acids like acetic acid and oxalic acid were formed as the end products during the complete degradation of benzene. With the increase in mono-valence, two-valence ions and hardness, Fenton''s efficiency decreased, respectively. Sequence Fenton reaction produced less phenol and its end products had smaller COD as compared to conventional Fenton process.
  • M. Malakootian, Sh Dowlatshahi, M. Malakootian Pages 72-78
    In Iran and the countries of the Eastern Mediterranean Region, bread has always been considered as the staple food of choice. Because of having high quantities of minerals and vitamins in bread, the hygienic condition of its production is of prime importance. This cross-sectional study was conducted in 302 bakeries in Kerman city, Kerman Province, Iran, from April 2004 to March 2005. Variables such as burning and pasting rate, pH, soda addition, salt rate in various types of bread as well as hygienic conditions of bakeries were analyzed. The results showed that because of bread wastage owing to the addition of soda as well as the pasting and burning rate (17.46% and 10.84%, respectively), more than 30% of the manufactured bread were out of direct cycle of consumption. Half of the bakeries added soda as a leavening agent to breads. The amount of salt used per production of each loaf of local bread: Sangak, indirect heat, machinery Taftoon and oven Taftoon bakeries was 48.72%, 33.33%, 31.13% and 8.97%, respectively, which was more than the approved standards. Moreover, only 24.2% of Kerman''s bakeries enjoyed suitable hygienic conditions. Aforementioned hinders must be considered as important signals to take immediate hygienic measures.