فهرست مطالب

Environmental Health Science and Engineering - Volume:5 Issue: 2, Spring 2008

Iranian Journal of Environmental Health Science and Engineering
Volume:5 Issue: 2, Spring 2008

  • تاریخ انتشار: 1387/01/11
  • تعداد عناوین: 10
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  • A. H. Mahvi Page 79
    Discharge of domestic and industrial wastewater to surface or groundwater is very dangerous to the environment. Therefore treatment of any kind of wastewater to produce effluent with good quality is necessary. In this regard choosing an effective treatment system is important. Sequencing batch reactor is a modification of activated sludge process which has been successfully used to treat municipal and industrial wastewater. The process could be applied for nutrients removal, high biochemical oxygen demand containing industrial wastewater, wastewater containing toxic materials such as cyanide, copper, chromium, lead and nickel, food industries effluents, landfill leachates and tannery wastewater. Of the process advantages are single-tank configuration, small foot print, easily expandable, simple operation and low capital costs. Many researches have been conducted on this treatment technology. The authors had been conducted some investigations on a modification of sequencing batch reactor. Their studies resulted in very high percentage removal of biochemical oxygen demand, chemical oxygen demand, total kjeldahl nitrogen, total nitrogen, total phosphorus and total suspended solids respectively. This paper reviews some of the published works in addition to experiences of the authors.
    Keywords: Sequencing batch reactor, domestic wastewater, industrial wastewater, organic removal, nutrients removal
  • R. Ramezankhani, A. A. M. Sharif, M. T. Sadatipour, R. Abdolahzadeh Page 91
    The contamination of surface waters through human activities has been intensified over the past years as population density has increased. Nickel is a metallic element and fuel combustion, nickel mining, refining waste, sewage sludge, and incineration are the major sources of nickel propagation. Nickel from various industrial wastewaters and other sources finally are disposed into water bodies. In this work, Karaj river was considered from 50º to 50º 14´longitudes and 35º 45´ to 35º 58´ latitudes and the presence of nickel was also assessed in this area. Sixteen stations were randomly selected and sediment samples were collected in polyethylene containers. Some water quality parameters such as pH, temperature, dissolved oxygen, electrical conductivity, were determind by direct on-site measurements. To measure COD, 16 water samples were collected in dark bottles and transferred to laboratory spatial parameters such as slope and distance from start point were also calculated by ARCGIS 9.2. The relation between Ni concentration with spatial parameters and water quality parameters were obtained by multivariate analysis. Results showed that there was a significant relation between Ni concentration in sediments and distance from start point and electrical conductivity.
    Keywords: Karaj river, pollution, nickel, sediment, mathematical model
  • A. Rezaee, M. T. Ghaneian, A. Khavanin, S. J. Hashemian, Gh. Moussavi Page 95
    In textile industry, advanced oxidation processes are used for degrading and removing color from dye baths which allow wastewater reuse. In this study, photochemical oxidation processes (UV-A/K2S2O8, UV-C/K2S2O8) and chemical oxidation process (dark/K2S2O8), were investigated in a laboratory scale photoreactor for decolorization of the Reactive blue 19 (RB19) dye from synthetic textile wastewater. The effects of operating parameters such as potassium persulphate dosage, pH, reaction time and UV source, on decolorization have been evaluated. The results of direct chemical oxidation showed that 50% of the dye was been removed using K2S2O8 in dark condition after 5h reaction time and photochemical oxidation showed that UV-C irradiation is more effective than UV-A for RB19 dye removal. The RB19 solution was completely decolorized under optimal potassium persulphate dosage of 5mmol/L and low-pressure mercury UV-C lamps (15w) in less than 30min. UV/K2S2O8 experiments showed higher color removal performance under acidic conditions (pH=3), and in this condition with 5mmol/L of potassium persulphate, 78.5% COD has been removed after 3h irradiation time. The decolorization rate fitted to pseudo-first order kinetics with respect of dye concentration. The reaction rate constants for photochemical degradation of RB19 were 0.014 and 0.237 for UV-A/K2S2O8 and UV-C/K2S2O8 processes respectively.
    Keywords: Photochemical oxidation, UV/persulphate, Reactive Blue 19 dye, Textile Wastewater, Decolorization
  • P. Chamanrokh, M. Mazaheri Assadi, A. Noohi, S. Yahyai Page 101
    Growth of previously isolated bacteria from Iranian oil reservoirs on different carbon and energy sources and under varying conditions have been used to produce a class of extracellular microbial protein-associated lipopolysaccharides named emulsan.Several Bacteria were previously isolated from Iranian oil reservoirs and designated as; Ilam-1 and Paydar-4. In present study, the isolated strains were compared with standard sample of Acinetobacter calcoaceticus RAG-1 from Persian Type Culture Collection (PTCC 1641), IROST. Among the isolated strains, two strains were found to produce an extracellular, emulsifying agent when grown in Mineral Salt Medium containing soya oil, ethanol or local crude oil. The isolated bacteria were cultured and further analysed using protein estimation, reducing sugar analysis, hemolytic activity, surface tension and emulsification activity tests. The crude emulsifier of RAG-1, PAYDAR-4 and ILAM-1 were concentrated from the cell-free culture fluid by ammonium sulfate precipitation to yield 1.89g, 1.78g and 1.69g of bioemulsan respectively. Emulsifying activity was observed over the entire production process. These investigations showed that emulsan produced by isolated Iranian crude oil reservoir were comparable with Acinetobacter calcoaceticus RAG-1 which is made of carbohydrate backbone as its hydrophilic part (N-acetyl-D-galactoseamine, N-acetylgalactoseamine uronic acid, diamino-6-deoxy-D-glucose) and fatty acid chain as its hydrophobic portion.
    Keywords: Emulsan, emulsification activity, protein estimation, reducing sugar analysis
  • P. Martin Deva Prasath, S. Arivoli Page 109
    Toxic activity of mercury chloride was tested in vivo on fresh water fish Catla catla. Acute toxicity tests were conducted to measure the impact of toxicity on the fishes within a short period at the various concentrations of HgCl2 (0.1, 0.5, 1, 1.5, 2, 2.5 and 3mg/L). The protein and carbohydrate were estimated using Anthrone by standard methods and enzymes such as Na+K, Mg2 and Ca2 adenoxide triphosphatases were determined caloriemetrically. Depletion of protein was observed at all exposure periods. The biochemical estimation values of carbohydrates in muscle, intestine and brain showed significant values with P<0.05. The activity of Mg 2 adenoxide triphosphatases in muscle, intestine and brain was studied and the maximum depletion was observed at 96h, 72h and 72h, respectively. Regarding activity of Ca 2 adenoxide triphosphatases in muscle, the maximum depletion of this enzyme activity in muscle was observed at all exposure periods, except 96h. In intestine, enzyme activity was gradually decreased in all exposure and an increase was found during 96h. In brain, the enzyme activity was observed at all exposure periods except 96h.
    Keywords: Toxic, protein, carbohydrate, enzyme, Catla catla
  • C. SHARMA, R. PUNDIR Page 117
    Delhi is the most urbanized city in India. Inventory estimates for the emissions of greenhouse gases and other pollutants like CO2, CO, NOx, and volatile organic compound from transport sector in Delhi, has been developed using bottom up approach provided by Intergovernmental panel on climate change (IPCC-1996). The impacts of policy option in transport sector like introduction of Compressed Natural Gas for public transport in Delhi and introduction of Euro-1 norms for vehicles have also been estimated. The emission inventory reveals that total emission of pollutants from different categories vehicles have increased during the period 1990-2000. For example, the CO2 emission (1000, tones) from gasoline driven vehicle (MC/SC) in Delhi has increased from 766 in 1990-91 to 1187 in 1999-00. The diesel driven vehicles Light commercial vehicles in Delhi has contributed to 577 CO2 in 1990-91, which increased to 9779 in 1999-00. For other pollutants also, which have been estimated here, an increase in total emission from gasoline and diesel driven vehicles has been observed during this 1990-2000 periods. This study shows that the over all contribution of pollutants in the total emissions from gasoline and diesel driven vehicles have increased in Delhi during this period. The present study also shows that the implementation of Euro-1 in 2000 in Delhi has resulted in the decrease of total emission of CO, HC, NOx, and volatile organic compound for all the classes of vehicle for which the revised vehicle emissions norms were implemented. However this decrease in emission has become inefficient due to increase in vehicle population.
    Keywords: Inventory, emission, green house gases
  • A. Rezaee, H. Godini, S. Dehestani, A. Khavanin Page 125
    In this study impregnated almond shell activated carbon by Zn° and ZnSO4 were used as adsorbent with a particle size of 10-20 mesh. The objective of this research was to determine the ability of impregnated activated carbon in nitrate removal. The modified activated carbon had 1mm effective size, with a uniformity coefficient of 1.18. Potassium nitrate solution was used in batch adsorption experiments for nitrate removal from water. The effects of nitrate concentration, activated carbon dosage and time of contact were studied. Experimental data showed that modified activated carbon by Zn° and ZnSO4 was more effective than virgin almond activated carbon for nitrate removal. The maximum nitrate removal was 64%-80% and 5%-42% for modified activated carbon and virgin activated carbon, respectively. While virgin activated carbon used, nitrate-N decreased from 20 to 15mg/L in 30min reaction. The final nitrate concentration was not in the standard range of WHO recommendations for water quality; while impregnated activated carbons were used, nitrate drcreased to <10mg/L. Maximum removal was over 16-17mg nitrate-N per 1g activated carbon for impregnated activated carbon. The experiments were conducted at pH=6.2, 20ºC and initial concentrations of 20mg/L nitrate-N. Increase in modified activated carbon dosage increased the nitrate removal efficiency. The equilibrium time was found to be 45min for modified activated carbon.
    Keywords: Activated carbon, nitrate, adsorption, zinc, zinc sulfate
  • M. H. Dehghani, K. Azam, F. Changani, E. Dehghani Fard Page 131
    The management of medical waste is of great importance due to its potential environmental hazards and public health risks. In the past, medical waste was often mixed with municipal solid waste and disposed in residential waste landfills or improper treatment facilities in Iran. In recent years, many efforts have been made by environmental regulatory agencies and waste generators to better managing the wastes from healthcare facilities. This study was carried in 12 educational hospitals of Tehran University of Medical Sciences. The goals of this study were to characterize solid wastes generated in healthcare hospitals, to report the current status of medical waste management and to provide a framework for the safe management of these wastes at the considered hospitals. The methodology was descriptive, cross-sectional and consisted of the use of surveys and interviews with the authorities of the healthcare facilities and with personnel involved in the management of the wastes. The results showed that medical wastes generated in hospitals were extremely heterogeneous in composition. 42% of wastes were collected in containers and plastic bags. In 75% of hospitals, the stay-time in storage sites was about 12-24h. 92% of medical wastes of hospitals were collected by covered-trucks. In 46% of hospitals, transferring of medical wastes to temporary stations was done manually. The average of waste generation rates in the hospitals was estimated to be 4.42kg/bed/day.
    Keywords: Medical waste, transportation, treatment, management, healthcare hospital
  • H. Alidadi, A. R. Parvaresh, M. R. Shahmansouri, H. Pourmoghadas Page 137
    The composting process is a useful method of producing a stabilized material that can be used as a source of nutrients and soil conditioner. Maturity of compost is essential for its optimal use as a soil amendment and a source of plant nutrients as well. Immature composts pose problems of malodors and flies and phytotoxicity and pollution during use. Stability and maturity both are required for compost quality control. Compost maturity tests can be classified into physical, chemical, plant, and microbial activity assays. In this study, several methods of evaluating the stability and maturity of composted biosolids were compared based on chemical and biological properties. The sludge used of windrow composting was obtained from the drying beds of South Isfahan wastewater treatment plant. The results showed that, C/N ratio after 100 days of composting reached to 15/1; NH4/NO3 ratio decreased with increase of the time dewatered sludge compost, which this loss is 57.3%. The content of volatile solids, 28.8% decreased with composting time. The number of fecal coliforms in the initial sewage sludge compost was 17.9´106 and at the end of composting was 898MPN/g of total solids and the compost process provided class A pathogen criteria. Use of chemical and biological parameters exhibited three phases: rapid decomposition (day 40), stabilization (day 80) and maturation (day 100) in biosolids compost. Thus, the biosolid compost was mature and ready for use as an agricultural substrate after about 100 days of composting.
    Keywords: Maturity, stability, compost, biosolids, wastewater treatment plant
  • M. Pourmahabadian, M. Adelkhah, K. Azam Page 141
    Heat stress is a common health problem throughout industry. Any heat stress evaluation requires some exposure assessment of climatic conditions, especially air temperature, humidity, and speed, along with the average temperature of the solid surroundings. In this paper workplace environmental climatic parameters were measured and then evaluated by Wet Bulb Globe Temperature, Corrected Effective Temperature, Heat Stress Index, and Allowable Exposure Time indices among 40 workers in a glass manufacturing unit in Tehran. Also, the effect of available heat control devices on heat stress indices was investigated. The results of this study showed that the obtained heat stress index in individual section and press units is exceeded from 100 (in individual section unit: 302.6, in press unit: 283.6). Also, it is found that the mean average of allowable exposure time in individual section and press units were 13.15 and 12.26 minutes exposure for one hour, respectively. No significant relationship was found between environmental parameters in three parts of body regions (height of head, abdomen and ankle) except for measured air velocity in both units (P<0.007). Positive correlation was found between wet bulb globe temperature, corrected effective temperature and heat stress index indices, but negative correlation was found between allowable exposure time and other indices. Mann Whitney non-parametric test revealed significant relationships in wet bulb globe temperature, corrected effective temperature, heat stress index and allowable exposure time indices when metallic shield was used as heat absorber.
    Keywords: Heat stress index, exposure, assessment, allowable, head load, environmental parameters