فهرست مطالب

Environmental Health Science and Engineering - Volume:5 Issue:3, 2007
  • Volume:5 Issue:3, 2007
  • تاریخ انتشار: 1386/05/11
  • تعداد عناوین: 10
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  • A. Akhavan Sepahi, I. Dejban Golpasha, M. Emami, A. M. Nakhoda Page 149
    Today, application of microorganisms for removing crude oil pollution from contaminated sites as bioremediation studies, was considered by scientists because other methods such as surfactant washing and incineration lead to production of more toxic compounds and they are non-economic. Fifteen crude oil degrading bacillus spp. were isolated from contaminated sites. Two isolated showed best growth in liquid media with 1-3% (v/v) crude oil and mineral salt medium, then studied for enzymatic activities on tested media. The results showed maximal increase in optical densities and total viable count concomitant with decrease in pH on fifth day of experimental period for bacillus S6. Typical generation time on mineral salt with 1% crude oil is varying between 18-20h, 25-26h respectively for bacillus S6 and S35. Total protein was monitored at determined time intervals as biodegradation indices. Increasing of protein concentration during the incubation period reveals that isolated bacillus can degrade crude oil and increase microbial biomass. These bacillus spp. reduced surface tension from 60 (mN/m) to 31 and 38 (mN/m), It means that these bacillus spp. can produce sufficient surfactant and have good potential of emulsification capacity. The results demonstrated that these bacillus spp. can utilize crude oil as a carbon and energy source.
    Keywords: Crude oil
  • F. Raihan, J. B. Alam Page 155
    In this study, groundwater quality in Sunamganj of Bangladesh was studied based on different indices for irrigation and drinking uses. Samples were investigated for sodium absorption ratio, soluble sodium percentage, residual sodium carbonate, electrical conductance, magnesium adsorption ratio, Kelly''s ratio, total hardness, permeability index, residual sodium bi-carbonate to investigate the ionic toxicity. From the analytical result, it was revealed that the values of Sodium Adsorption Ratio indicate that ground water of the area falls under the category of low sodium hazard. So, there was neither salinity nor toxicity problem of irrigation water, so that ground water can safely be used for long-term irrigation. Average Total Hardness of the samples in the study area was in the range of between 215 mg/L at Tahirpur and 48250 mg/L at Bishamvarpur. At Bishamvarpur, the water was found very hard. Average total hardness of the samples was in the range of between 215 mg/L at Tahirpur and 48250 mg/L at Bishamvarpur. At Bishamvarpur, the water was found very hard. It was shown based on GIS analysis that the groundwater quality in Zone-1 could be categorized of "excellent" class, supporting the high suitability for irrigation. In Zone-2 and Zone-3, the groundwater quality was categorized as "risky" and "poor" respectively. The study has also made clear that GIS-based methodology can be used effectively for ground water quality mapping even in small catchments.
    Keywords: Sodium absorption ratio, residual sodium carbonate, total hardness, magnesium adsorption ratio, kelly s ratio
  • M. Hajimahmoodi, M. Hanifeh, M. R. Oveisi, N. Sadeghi, B. Jannat Page 167
    Green tea is one of the important sources of bioactive compounds which have been used in folk medicine for many centuries. This study aimed to compare in vitro antioxidant power of different types of green tea (Camellia sinensis). Antioxidant activity of methanolic (50%) extracts of five green tea samples was investigated according to Ferric reducing ability power method. Total phenolic contents were analyzed using a spectrophotometric technique, based on the Folin-ciocalteau reagent, and calculated as gallic acid equivalents per gram dry weight. Total flavonoid and antocyanidin were also investigated according to aluminum chloride and vanillin colorimetric assay respectively. Total antioxidant activity varied from 0.554±0.042 in Avicen green tea sample to 3.082±0.150 mmoL FeII/g in Chinas green tea and total phenolic content ranged from the 0.030±0.001 in Avicen green tea sample to 0.196±0.012 g gallic acid per gram dry weight in Ahmad green tea. A linear positive relationship existed between the antioxidant activity, total phenolic, flavonoid and antocyanidin content of the tested green tea samples. Green tea samples possess relatively high antioxidant activity due to contribution of phenolic compounds. The present study showed that green tea samples which are more frequently consumed in Iran are strong radical scavengers and can be considered as good sources of natural antioxidants for medicinal and commercial uses.
    Keywords: Antioxidant activity, green tea, phenolic compound, flavonoid compound, antocyandin compound
  • N. Kalantari, S. Ghaffari Page 173
    Iron is essential to virtually all organisms but it can be toxic in excess. High concentration of iron and other trace elements could restricted bacterial growth and modify their metabolic pattern as well. However, this study aimed to find out the influence of iron, chromium, cadmium and synergism or antagonism between these elements on growth of a gram negative bacterium. In the series of experiments, E. coli has been cultured in a nutrient broth which supplemented with Fe, Fe, Cr, Cd alone or in combination with together, at 37°C for 5 h. Bacterial growth was measured every half an hour using spectrophotometer. Findings obtained from this study indicated that bacterial growth reduced at presence of 1 mM/L concentration of Fe and 0.5 mM/L Fe in comparison with control. Growth of the bacteria was completely inhibited by 1 mM/L concentration of iron (II). Chromium has also inhibitory effects on growth of the bacteria and cadmium is very toxic. Cr and Cd have antagonism effect with iron on the growth of bacteria. This work suggested that trace elements could interact in their metabolism in bacteria. It has also concluded that toxic effects of trace element could be another view against pathogenic bacteria particularly in complex with antibacterial activity of various antibiotics.
  • S. J. Ojolo, A. I. Bamgboye, B. S. Ogunsina, S. A. Oke Page 179
    There is an increasing worldwide interest in the effective utilisation of municipal solid wastes as an avenue of reducing its high cost of clearing. Municipal solid wastes are usefully converted into a medium grade fuel (biogas) to reduce its nuisance value to the environment. In this paper, the potential of vegetable (putriscible) component of municipal solid wastes was examined in terms of biogas production. The vegetable component of the waste was used as substrate in a batch-fed 200 dm3 capacity anaerobic digester, which was consecutively loaded with a 10-20 kg ranged weight of vegetable. The total solid (TS) of substrate was 8-10% over a retention period of 40 days. The temperature of the substrate during bio-digestion was maintained within 29ºC and 33ºC. The average biogas yield varied from 5.15 dm3/kgTS to 5.83 dm3/kgTS. From the digestion experiments, a regression equation, called the municipal solid wastes energy value model, was derived. This model estimates the biogas production from municipal solid wastes. For the predictive model formulation, a relationship between retention time and the daily/total biogas yield was explored. The polynomial function significantly represents the models formulated for the different quantity of substrate loaded. This strongly suggests that the polynomial series is best suited to predict the relationship between retention time and the quantity of substrate loaded for the experiment. This tool is useful in optimising biogas production from energy materials, and requires further validation and refinement. Hopefully, this study advances this increasingly growing area of municipal solid wastes research.
    Keywords: digester, energy model, statistical analysis
  • H. Asilian, M. Nasseri Nejad, S. B. Mortazavi, M. J. Jafari, A. Khavanin, A. R. Dehdashti Page 187
    Dust consists of tiny solid particles carried by air currents. These particles are formed by many different processes. One of these processes is polymerization of inert plastic such as Polyvinyl Chloride production plant. According to the Occupational Health and Safety Assessment Series requirements, section 4.4.6, occupational health and safety risks must be defined and controlled where needed. This field study was conducted to evaluate the occupational exposure of packaging operators to airborne polyvinyl chloride dust in order to health risk assessment and recommend feasible controlling methods. The mass concentration of polyvinyl chloride particulate was measured in two fractions according to the particle size that expressed as total and respirable particulates. The Air Sampling Methods, Methods for the Determination of Hazardous Substances 14/3, of Health and Safety Executive were used as a standard sampling protocol. The average mass concentrations for respirable and total particulates were measured 3.54±0.3 mg/m3 and 11.89±0.8 mg/m3 respectively. Also health risks of studied condition were estimated as significant level, category one, therefore the risk must be reduced below the standard level. According to the work requirements to reduce the emission rate and mitigate the health risk exposure, a local exhaust ventilation system design was recommended for bag-filters of hopper tank.
    Keywords: Polyvinyl chloride, personal sampling, total particles, respirable particles, chemical health risk
  • A. Khanafari, S. Eshghdoost, A. Mashinchian Page 195
    The different methods are used for the removal of heavy metals as important contaminants in water and wastewater. Biosorption is an alternative to traditional physicochemical in removing toxic metals from wastewaters and groundwater resources. In this study biosorption of lead and chromium ions from solution was studied using Bacillus circulans isolated from Anzali wetland in batch and biofilter modes and optimum conditions were determined. The experimental results showed 900-950 mg/L and 1050-1100 mg/L, for minimum bactericidal concentration and minimum inhibitory concenteration for lead and chromium, respectively. Results of metal concentration in solution containing 500 mg/L in batch culture showed a reduction about 65% and 48% in five and four days for lead and chromium, respectively. The highest value of lead and chromium uptake in solution with 500 mg/L was 78% and 40% in biofilter mode, respectively. The biosorption of lead and chromium were increased up to pH=5.5, 6, 5.5 and 7, respectively. In the other hand, maximum sorption occurred at neutral pH. There was a significant decreasing of biosorption levels by lowering pH fewer than 3. Accumulation of lead and chromium was determined by scanning electron microscopy analysis of the biofilm exposed to 500 mg/L metal concentration. Based on this analysis, the highest metal concentrations were observed in regions with including bacteria.
    Keywords: biofilter, bacillus circulans
  • R. Mirzaee, A. Kebriaei, S. R. Hashemi, M. Sadeghi, M. Shahrakipour Page 201
    The present study was done to assess cement dust exposure and its relationship to respiratory health effects, both acute and chronic respiratory symptoms and ventilatory function impairment among Portland cement factory workers in Khash located in the south part of Iran. A cross-sectional study was conducted at Khash Portland cement producing factory in Iran in 2001. A total of 170 exposed and 170 unexposed employees were selected. Air transmitted personal respirable dust and total dust samples were collected in a full-time (8h/day) shift. Dust level was determined by the gravimetric method. An interviewer-administered questionnaire was used to collect information and history of respiratory health among workers (exposed and unexposed to dust) and measurements of lung function were made using a spirometer in both groups. Concentrations of personal respirable dust ranged from 3.7 mg/m3 in the kilns to 23 mg/m3 in the ore crushing area, and total dust ranged from 15 mg/m3 in the kilns to 95 mg/m3. Cough and phlegm, with or without shortness of breath, were significantly related to dust concentration. Measuring pulmonary functions of workers exposed to dust and unexposed group showed a significant decrease in vital capacity, forced vital capacity, FEF25-75 and Forced Expiratory Volume in the first second (P<0.05). Findings suggest that occupational exposure to Portland cement dust may lead to higher prevalence of respiratory symptoms and the reduction of ventilator capacity due to existence of quartz in row material of cement dusts. The study revealed that cement dust exposure is associated with acute as well as chronic respiratory health effects. It is recommended that engineering measures must be taken to reduce the dust level in cement factories, accompanied with health monitoring of exposed employees.
    Keywords: respiratory symptoms, lung function
  • M. Soleimani, J. Rafinejad Page 207
    House dust mites have been shown to be strongly associated with allergic respiratory diseases such as, bronchial asthma, rhinitis and atopic dermatitis in the world. The climatic conditions of Bandar-Abbas, which is located in a coastal area and has a humid subtropical climate, provide a suitable place to proliferate mites. The aim of this study was to determine the contamination rate and analyze the house dust mite fauna in hotels and inns in Bandar-Abbas that had not been investigated previously. In this study 6 hotels and 6 inns were selected randomly in six areas of Bandar-Abbas. Two dust samples were collected from each place with a vacuum cleaner. One square meter of carpets and mattresses were vacuumed for a period of 1 min. Then the samples were cleared in lactic acid and then mites were mounted in Hoyer''s medium for study and identification. A total of 2644 mites were collected and identified. The major mite family was Pyroglyphidae (98%). Dermatophagoides pteronyssinus was the most frequent and most numerous species recorded, occurring in 91% of samples examined and forming 88% of the Pyroglyphidae and 86% of the total mite populations. The family Cheyletidae was less commonly found with Cheyletus malaccensis (2%). Most of the mites were isolated from the carpets (57.5%), and a smaller number from mattresses (42.5%). Mites were present in 96% of the dust samples. Results revealed that all inns and 83% of hotels were contaminated by more than one species of mite and 34% of them had a population of more than 100 mites /g dust. This rate of contamination can be a major risk factor in asthma and other respiratory allergic diseases.
    Keywords: mite, public residence
  • M. Majlesi Nasr, A. R. Yazdanbakhsh Page 211
    Nowadays, water resources shortage is one of the most important issues for environmental engineers and managers as well as its conservation due to population growth and ever-increasing water demands. Besides, hospital wastewater has the same quality as municipal wastewater, but may also potentially contain various hazardous components. In this paper, physical and chemical specifications of produced wastewater in hospitals of Iran were investigated experiments. Results were compared with the effluent parameters of wastewater standards of Iranian Department of the Environment. 70 governmental hospitals from different provinces of Iran were selected by purposive (non-random) sampling method. For data analysis, SPSS and EXCEL softwares were applied. The findings of the study showed that 52% of the surveyed hospitals were not equipped and 48% were equipped with wastewater treatment systems. The mean of Biochemical Oxygen Demand, Chemical Oxygen Demand and Total Suspended Solids of the effluent of wastewater treatment systems were reported as 113, 188 and 99 mg/L respectively. Comparison of the indicators between effluents of wastewater treatment systems and the standards of Departments of the Environment, showed the inefficiency in these systems and it was concluded that despite the recent improvements in hospital wastewater treatment systems, they should be upgraded based on the remarks in this paper.
    Keywords: septic tank