فهرست مطالب

Environmental Health Science and Engineering - Volume:2 Issue:3, 2005
  • Volume:2 Issue:3, 2005
  • تاریخ انتشار: 1384/04/20
  • تعداد عناوین: 10
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  • M. Shafiepour, H. Kamalan Pages 145-152
    Since there is a rise of motorcycles population as well as other motor vehicles, it seems that air Pollution deterioration should be studied as one of its environmental impacts. The main objective of this study was to develop a number of scenarios in order to determine the amount of Tehran''s air pollution attributable to motorcycles and select the best and the most probable case to be recommended for implementation. The first step was to collect data such as the number of active motorcycles, daily traffic volume, average traveling speed and actual emission factors. For this purpose, a detailed questionnaire was designed to be completed by field surveys and measurements. The collected data were compared with traffic volume data, manufacturing statistics and the latest production capacity forecast in this field. Finally, with this data and emission factors for each type of motorcycle, an emissions inventory model was chosen to provide annual emissions from motorcycles in Tehran in different scenarios. The results showed that in 2002, there has been about 450''000 active motorcycles (4-stroke 58%, 2-stroke 28%, and moped 14%) with average speed of 40 km/h and average mileage of 110 km/d. Five scenarios were developed. The best scenario was "Changing all motorcycles to 4-strokes under EU-97 standard" which would result in reduction of NMVOC by 75%, CO by 35% and PM10 by 88%.
  • A. Almasi Pages 153-157
    Municipal wastewater is one of the most important pollution sources for water supply resources. Identification and enumeration of pathogenic agents particularly pathogenic Vibrios are beneficial for controlling and prevention planning of the infectious diseases. This research was carried out to identify the distribution of the recognized pathogenic Vibrios with emphasizing on identification of Vibrio cholera in the wastewater of Kermanshah city western Iran in 2002. The method of study was cross sectional descriptive. There were 8 discharge outlet domestic wastewaters, which had been chosen as sampling sites. Samples were collected weekly in randomized manner in daytime. Three hundred and thirty nine samples were collected and analyzed. The results indicated site 7 with 5 positives, sites 4 and 8 each with 3, site 5 with 2, sites 2, 3 and 6 each with one positive, whereas, there was not any Vibrio detected in site 1. The most positive samples were seen in spring, late summer and early autumn. The positive results were detected on May, June, September, and October. Among positive samples, Vibrio parahemolyticus, could be regarded based on differentiation tests. Vibrio cholera was not seen. It seems that the presence of Vibrio parahemolyticus was due to some food store deal with distribution of seafood. Hence it is suggested that this relationship could be considered through analytical study using PCR for detection of Vibrios.
  • R. Nabizadeh, K. Naddafi, R. Saeedi, A. H. Mahvi, F. Vaezi, K. Yaghmaeian, S. Nazmara Pages 159-168
    Contamination of the aqueous environment by heavy metals is a worldwide environmental problem. Biosorption of lead (II) and cadmium (II) from aqueous solutions by brown algae Sargassum spp.biomass was studied in a batch system. The heavy metals uptake was found to be rapid and reached to 88-96% of equilibrium capacity of biosorption in 15min. The pseudo second-order and saturation rate equations were found in the best fitness with the kinetic data (R2 > 0.99). The data obtained from experiments of single-component biosorption isotherm were analyzed using the Freundlich, Langmuir, Freundlich-Langmuir and Redlich-Peterson isotherm models. The Redlich-Peterson equation described the biosorption isotherm of Pb2+ and Cd2+ with high correlation coefficient (R2 > 0.99) and better than the other equations. The effect of Na+, K+, Mg2+ and Ca2+ on the biosorption of Pb2+ was not significant, but the metal ions affected the biosorption of Cd2+ considerably. According to the Langmuir model, the maximum uptake capacities (qm) of Sargassum spp. for Pb2+ and Cd2+ were obtained as 1.70 and 1.02mmol/g, respectively. Although the Sargassum spp. used in this study can be classified as an efficient biosorbent.
  • H. Nanbakhsh Pages 169-176
    Urban drainage systems are vital infrastructure assets, which protect our cities from flooding and transmission of waterborne diseases. The objective of this research was to assess the treatment efficiencies of experimental stormwater detention (extended storage) systems receiving concentrated runoff that had been primary treated by filtration with different aggregates. Five detention systems with different packing order arrangements of aggregates and plant roots were used in the system to test the effects of gravel, sand, ecosoil, block paving and turf on the water treatment performance. Inflow water, polluted by road runoff, was collected by manual abstraction with a 2 litter beaker from randomly selected gully pots the near by main roads. Several parameters such as BOD5, NO3, PO4, NH4, SS, TS, DO, pH, EC, NTU and temperature were examined based on standard method book. Results showed that concentrations of biochemical oxygen demand (BOD5) in contrast to suspended solids (SS) were frequently reduced to below international secondary wastewater treatment standards. The BOD and SS concentrations within the outflow from the planted system compared to the unplanted gravel and sand systems were similar. However, BOD in the outflow of system 5 was lower than other systems. The denitrification process was not completed. This resulted in higher outflow than inflow nitrate-nitrogen concentrations. An analysis of variance indicated that some systems were similar in terms of most of their treatment performance variables including BOD and SS. It follows that there is no need to use additional aggregates with high adsorption capacities in the primary treatment stage from the water quality point of view.
  • A. Khodadadi, M. Abdolahi, P. Teimoury Pages 177-182
    Utilizing cyanide compounds in mining and chemical industry is one of the most important environmental issues due to the acute toxic properties of many cyanide compounds to humans and aquatic life. Cyanide tends to react readily with most other chemical elements, producing a wide variety of toxic, cyanide related compounds. This research was aimed at investigating a feasible and economical technique for the detoxification of cyanide from the tailing effluent of Muteh gold mine in Isfahan, Iran. In this research cyanide detoxification was achieved through the oxidation of cyanide by hydrogen peroxide using various hydrogen peroxide solutions at pH levels between 7-13 and temperatures between 12-65 °C using copper sulfate as a catalyst. The optimum pH and dose of hydrogen peroxide for complete cyanide removal in the presence of 30 mg/L copper sulfate as a catalyst were determined as 9.7 and 9.98 g/L, respectively. At high temperatures > 35°C, cyanide was completely removed perfectly at constant pH = 9.7 which was mainly due to cyanide evaporation in the form of HCN.
  • M. Reyahi Khoram, M. Shariat, N. Moharamnejad, A. Azar, H. Mahjub Pages 183-188
    Geographic Information System (GIS) is the best suitable system for land evaluation. In this research, at the first step, the Makhdoum''s model is introduced‚ and then Hamadan Province, from aquaculture point of view and capabilities of the lands to fulfill aquaculture activities is evaluated. GIS was used for the mentioned purposes. The software used was Arc View (version 3.2 a), with the UTM projection. For evaluation, Mc Hark method of Maps overlaying was utilized. According to the results, the suitable surface area for aquaculture activities was introduced, which was equal to 13.1 percent of Hamadan Province. According to the evaluations, this province has limited potentials for aquaculture activities. Therefore, it is necessary to pay attention to these limitations in development plans.
  • A. Mesdaghinia, M. T. Rafiee, F. Vaezi, A. H. Mahvi Pages 189-194
    Although the removal of colloidal particles continues to be an important reason for using coagulation, a newer objective, the removal of natural organic matter (NOM) to reduce the formation of disinfection by-products (DBPs), is growing in importance. Enhanced coagulation is thus introduced to most water utilities treating surface water. Bench-scale experiments were conducted to compare the effectiveness of alum and ferric chloride in removing DBPs precursors from eight synthetic water samples, each representing a different element of the USEPA’s 3×3 enhanced coagulation matrix. The effect of enhanced coagulation on the residual metal (aluminum/iron) concentration in the treated water was assessed as well. The removal of total organic carbon (TOC) was dependent on the coagulant type and was enhanced with increasing coagulant dose, but the latter had no further considerable effect in case of increasing to high levels. For all the treated samples coagulation with ferric chloride proved to be more effective than alum at similar doses and the mean values of treatment efficiencies were 51% and 32% for ferric chloride and alum, respectively. Ferric chloride was therefore considered the better chemical for enhancing the coagulation process. Besides, due to less production of sludge by this coagulant, it would be predicted that treatment plants would be confronted to fewer problems with respect to final sludge disposal. Measurements of residual metal in treated water indicated that iron and aluminum concentrations had been increased as expected but the quality of water concerning the residual metal deteriorated much more in cases of under-dosing. Despite expecting high residual Al and Fe concentrations under enhanced coagulation, metal concentrations were frequently remained low and were not increased appreciably.
  • A. Khavanin, S. M. Mousavian, S. B. Mortazavi, A. Rezaee, H. Asiliyan Pages 195-200
    Methyl tertiary-butyl ether (MTBE) has been commonly used as a fuel additive because of its many favorable properties that allow it to improve fuel combustion. Unfortunately, increased production and use have led to its introduction into the water supplies. Accordingly, research studies have been initiated to investigate the treatment of contaminated water. Degradation of MTBE in aqueous solution by Fenton reagent (Fe2+ and H2O2) was investigated. This study used Fenton reagent to oxidize MTBE with an attempt to explore the behavior of MTBE decomposition and measure how factors such as pH, [H2O2] and [Fe2+] may influence the degradation of MTBE, and finally the optimum conditions were obtained. Under optimum conditions of 50 mL H2O2, 0.65 g/L Fe2+, pH=3-4 and room temperature, the initial 1000 mg/L MTBE solution was reduced by 99% within 120 min. The results showed that application of Fenton reagent was an effective method for degradation of MTBE.
  • A. Maleki, A. H. Mahvi, F. Vaezi, R. Nabizadeh Pages 201-206
    Phenol is a potential hazard to human health and the environment. The sonochemical degradation of phenol in aqueous solution was investigated by use of a 35 kHz bath sonicator. Experiments were performed at initial phenol concentrations varying from 1 to 100 mg/L. The effects of parameters such as pH and initial phenol concentration on the sonochemical degradation and bioassay test have been studied. The results of the study showed that the ultrasonic phenol degradation increased with decreasing the pH values and phenol concentration. But the rates of phenol degradation under different conditions had always been quite low. It was found that the rate of ultrasonic phenol degradation was first high but it was later substantially reduced and the experimental data fitted well with first order reaction rate equation. Bioassay tests showed that phenol was toxic to Daphnia magna and so resulted in quite low LC50 values. Comparison of toxicity units (TU) of phenol and the effluent flow showed that TU value for effluent was 1.65 times lower than that obtained for phenol. Thus, sonication was able to eliminate the toxicity of by-products which were formed during the degradation of phenol.
  • A. Nazarian, M. Mousawi Pages 207-211
    The broadness application of organophosphorus compounds has abounded the number of its polluted areas. Bioremediation has widely focused on insitu bacterial degradation of organophosphorus residues in the world. Therefore, in this research six numbers of samples from two different sources, soil and water randomly were isolated using different organophosphorus pesticides containing mineral solution without supplementation. More than 100 isolated strains were selected according to their simultaneous optimal growth on mineral medium with organophosphorus and Mac Conkey,s agar. More than 50 percent of them were lost above resistance. The resistant strains were identified by two methods, the biochemical convention and API 20E procedure with positive agreement. The identified strains belonged to Pseudomonas and Flavobacterium species. The maximum tolerant concentrations of different organophosphorus pesticides by these resistant strains were 2.5, 4 and 8 g/L of guthion, methyl parathion and Dimethoate, respectively. The resistance to these pesticides due to organ phosphorous degrading plasmids had the ability to express hydrolytic enzymes. Resistant bacteria lost these plasmids by acridin orange and could translocate to sensitive strains. Thus, certain environmental bacteria could be used as protection tools against antinerve agents.