فهرست مطالب

Environmental Health Science and Engineering - Volume:8 Issue:4, 2012
  • Volume:8 Issue:4, 2012
  • تاریخ انتشار: 1390/10/28
  • تعداد عناوین: 12
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  • F. Qaderi, B. Ayati, H. Ganjidoust Page 295

    Nowadays formaldehyde is used as raw material in many industries. It has also disinfection applications in some public places. Due to its toxicity for microorganisms, chemical or anaerobic biological methods are applied for treating wastewater containing formaldehyde.In this research, formaldehyde removal efficiencies of aerobic biological treatment systems including moving bed biofilm (MMBR) and sequencing batch reactors (SBR) were investigated. During all experiments, the efficiency of SBR was more than MBBR, but the difference was not significant statistically. According to the results, the best efficiencies were obtained for influent formaldehyde COD of 200 mg/L in MBBR and SBR which were 93% and 99.4%, respectively. The systems were also capable to treat higher formaldehyde concentrations (up to 2500 mg/L) with lower removal efficiency. The reaction kinetics followed the Stover-Kincannon second order model. The gram-positive and gram-negative bacillus and coccus as well as the gram-positive binary bacillus were found to be the most dominant species. The results of 13C-NMR analysis have shown that formaldehyde and urea were converted into N-{[(aminocarbonyl) amino] methyl}urea and the residual formaldehyde was polymerized at room temperature.

    Keywords: Aerobic treatment, Formaldehyde, Moving bed reactor, Sequencing batch reactor, Kinetic coefficients, 13C, NMR
  • M. Mokhtari, M. Nikaeen, M. M. Amin, A. Hasanzadeh Page 307

    Composting is a reliable technology for production of stabilized organic matter that is suitable for agriculture, but this process should be carefully monitored with appropriate indices. Quality of compost is important from maturity and stability viewpoint, but in most compost factories proper attention is not paid to it. This study was designed to evaluate the stability indices in municipal solid waste composting, for selecting the best index in quality monitoring of the wastes. Processed and shredded municipal solid waste from Isfahan compost plant was used as raw material in an in-vessel composting process. A cylindrical reactor with 1 m height and 50 cm diameter made of Pyrex glass was designed. Air was supplied at a specifically flow rate 0.2 L/min.kg to maintain aerobic condition. NH4+/ NO3 ratio, dehydrogenase enzyme activity (DA), pH, oxidation reduction potential (ORP or Eh) and specific oxygen uptake rate (SOUR) were used as stability indices. These parameters were measured during 40 days of composting process. Changes in these parameters during this period were surveyed and analyzed. Statistical analysis was carried out to choose best of them. Results showed that among the indices, SOUR can show the different stages of microbial decomposition and a numerical value for compost stability also SOUR value less than 2 mg O2/gVS.h can show the full stability of compost.

  • C. Braghină, D. Peptenatu, C. Draghici, R. D. Pintilii, A. Schvab Page 315

    The study is a concise form of some present days researches within the Interdisciplinary Centre for Advanced Researches on Territorial Dynamics within the University of Bucharest, which had as main major objective to identify and to underline the instability from the natural environment, determined by coal exploitation, as well as to identify the efficient management systems in some areas located in the south-western part of Romania, Oltenia. Researches identified the major effects these economic activities have upon air pollution, slopes’ dynamic, air and soil pollution. A special importance is given to the human component within territorial systems, as population is often dislodged to other localities and this phenomenon implies many social and economic consequences. One of the most important aggressions upon natural and built environment is that related to the landscape damage, following exploiting and processing rough material in order to obtain the final product, the coal. The direct impact of mining activities upon environment may be translated by a local biodiversity decrease, even if these coal mines are rehabilitated after they’re closed. Therefore, an integrated approach is necessary and it must refer to the way of administering mines for long term, by common actions of all the implied factors (government, mining companies and the local communities). The scientific demarche of building the model of environment management in the areas affected by mining took into account the new European context, which represents a supra system imposing the strategic coordinates where the process of managing territorial instability takes place.

  • C. Thenmozhi, V. Vignesh, R. Thirumurugan, S. Arun Page 325

    Malathion was used in vivo on fresh water fish Labeo rohita to study its toxicity. The acute toxicity tests were conducted during certain intervals in various concentrations (5, 10, 15, 20, 25 and 30 mg/L) of malathion. The physical and chemical analyses of water were carried out by following APHA methods. While treating with malathion, the percentage of fish mortality was assessed during 24, 48, 72 and 96 hours. The lethal and sub-lethal concentration of malathion were found to be LC100 (25 mg/L) and LC0 (5 mg/L), respectively. The antioxidant enzyme activity (Catalase 43.1±2.3, 16.5±0.57, 23.9±0.17 μ moles of phenol liberated/min/100mg protein and Glutathion-S-transferase (GST) 270.5±0.16, 143.2±1.03, 215.5±0.72 μ moles of phenol liberated/min/100mg protein), in the liver, muscle and gill, respectively increased during the accumulation of malathion, whereas it decreased (Catalase 17±1.44, 7.9±0.23, 10.7±0.69 μ moles of phenol liberated/min/100mg protein and GST 219.5±1.12, 108.1±0.34, 160.2±0.46 μ moles of phenol liberated/min/100mg protein) during depuration period. The effects of malathion resulted in the gradual decrease of nucleic acids, protein, free amino acids (FAA) and glycogen. During recovery period, the levels of biochemical components progressively increased indicating a probable recovery from the disruption of internal organ. Hence, the pesticide intoxication has made a disturbance in normal functioning of cells with significant alterations in the fundamental biochemical mechanisms of fish. It suggests that the continuous exposure of pesticide leads to abnormal changes causing fish to death.

  • S. M. Tabatabaei, S. Dastmalchi, A. Mehrizad, P. Gharbani Page 333

    The removal of 4-nitrophenol (4NP) from aqueous solution by ozone combined with nano-ZnO was investigated in a laboratory-scale reactor in which pH of solution, ZnO dosage and initial 4-nitrophenol concentration were considered as variables. The degradation of 4-nitrophenol was determined using UV-Vis and HPLC methods. Interestingly, the degradation of 4-nitrophenol was high under acidic condition where the degradation was about 93% at initial phenol solution pH=3. It was due to aggregation of nano-ZnO particles above pH=6.5. This result was different from the case of ozonation alone, in which higher pH had positive effect on the degradation of 4-nitrophenol due to the formation of hydroxyl radical. As expected, degradation efficiency increased by increasing the nano ZnO dosage and initial 4-nitrophenol concentration. It was found that the nanosized ZnO enhanced the degradation of ozone and the catalytic ozonation enhanced the degradation of 4-nitrophenol on the surface of the nanosized ZnO. In addition, the degree of degradation was also determined indirectly through Total Organic Carbon (TOC) of the samples. Carbon mineralization of 4-nitrophenol was obtained as 13.68% and 60.34% during ozonation and nano-ZnO catalytic ozonation, respectively, after 30 min reaction, proving that combined ozonator and nano-ZnO for reduction of TOC is more efficient. Also a high degree of nitrogen mineralization during catalytic ozonation was achieved at pH= 3 (7.61mg/L).

  • S. Babaee, M. R. Sabour, H. Kamalan Page 343

    Heat loss through walls in houses is remarkable and it shares about 25% of total loss. Utilizing Foam Lightweight Concrete (FLC) block in walls may lead to reduction in both gas consumption and greenhouse gas emissions. This is due to heat insulation property of the block and consequently less energy consumption. The main objective of this research was to investigate how FLC block can save natural gas usage within building envelop. A typical residential building was simulated for pressed brick, terra-cotta block, 3D panel, and FLC block by utilizing Behsazan software. Afterwards, building gas consumption and relevant carbon dioxide emissions were compared for abovementioned wall materials, while the building area was constant and its height was variable. Results showed that annual gas reduction attributed to utilizing FLC block walls with different heights varies from 25.7% to 30.6% and from 18.5% to 23.3% in comparison with pressed brick and terra-cotta block walls, respectively. This reduction for 3D panel walls was about 4.6%. Moreover, CO2 emission reduction depending on the number of floors for FLC block walls with pressed brick, terra-cotta block, and 3D panel walls were equal to 20.8 to 24, 15 to 18.3, and 3.4 to 3.8 kg CO2/m2, respectively.

  • M. Ghanbarian, R. Nabizadeh, A. Mahvi, S. Nasseri, K. Naddafi Page 353

    The possibility of linear alkyl benzene solfunate (LAS) photocatalytic degradation through application of TiO2 nanoparticles was investigated. 10(mg/L) of LAS has been affected by either UV or TiO2 and simultaneous use of both of them in separated experiments. Moreover, the effect of initial concentrations of LAS and TiO2, pH, present various anions and different UV power was studied to determine the optimal operating conditions for LAS degradation in water. The amount of mineralization of LAS was reported by measuring the primary and final COD of the solution that was irradiated under optimized conditions. Maximum degradation was obtained at acidic pH, 50 mg/L of TiO2 and 30 minute irradiation time. It was also shown that 99.5% of LAS was degraded in optimal conditions. Kinetic analysis indicated that photo catalytic degradation rates of LAS can be approximated by pseudo-first order model. Measuring the initial and final COD of illuminated solution under optimized conditions, indicated that almost complete mineralization of LAS was occurred. Based on the results, UV/TiO2 process may be effectively applied in LAS removal in low concentrations but this process is not economically efficient in high concentrations.

  • G. Kumar, N. Srivastava Page 361

    Food additives are the substances that are intentionally added to modify visual appearance, taste, texture, processing or the storage life of food. There has been significant controversy associated with the risks and benefits of food additives. The effect of different concentrations of food additives viz. boric acid and sunset yellow on the chromosomes of Trigonella foenum-graecum L. was investigated. Four concentrations of the two food additives (0.25, 0.50, 0.75 and 1%) were used for 3 hours. All concentrations of boric acid and sunset yellow showed mitoinhibitory effect in root tips of Trigonella foenum-graecum and increase in chromosomal aberrations. Various types of metaphasic and anaphasic aberrations were scored and it was found that metaphasic aberrations were more prominent than the anaphasic aberrations. The most observed aberrations induced by boric acid were stickiness at metaphase, bridges at anaphase, stickiness at anaphase, and scattering at metaphase, while the most prevalent aberrations caused by sunset yellow were precocious movement, unorientation at anaphase, scattering at metaphase and unorientation at metaphase. The result of present study clearly establishes the genotoxic behavior of boric acid and sunset yellow.

    Keywords: Chromosomal aberrations Sunset yellow, Boric acid, Food additives Trigonella foenum, graecum
  • A. M. Deshpande, S. Satyanarayan Page 367

    Considering the high pollution potential that the synthetic Bulk Drug industry Wastewater (BDW) possesses due to the presence of variety of refractory organics, toxicity evaluation is of prime importance in assessing the efficiency of the applied wastewater treatment system and in establishing the discharge standards. Therefore, in this study the toxic effects of high strength bulk drug industry wastewater before and after electrochemical treatment on common fish Lebistes reticulatus-(peter) were studied under laboratory conditions. Results indicated that wastewater being very strong in terms of color, COD and BOD is found to be very toxic to the studied fish. The LC50 values for raw wastewater and after electrochemical treatment with carbon and aluminium electrodes for 24, 48, 72 and 96 hours ranged between, 2.5-3.6%, 6.8-8.0%, 5.0-5.8% respectively. Carbon electrode showed marginally better removals for toxicity than aluminium electrode. It was evident from the studies that electrochemical treatment reduces toxicity in proportion to the removal efficiency shown by both the electrodes. The reduction in toxicity after treatment indicates the intermediates generated are not toxic than the parent compounds. Furthermore, as the electrochemical treatment did not result in achieving disposal standards it could be used only as a pre-treatment and the wastewater needs further secondary treatment before final disposal.

  • A. Naghizadeh, S. Nasseri, Sh. Nazmara Page 375

    Groundwater recourses may be contaminated with trichloroethylene (TCE) which is used in electronic, electric, dry cleaning and other similar industries and often treated by air stripping, which TCE in its vapor form is stripped from groundwater by air and is emitted into the atmosphere without any additional treatments. Carbon nanotubes are expected to play an important role in sensing, pollution treatment and separation techniques. In this study adsorption of trichloroethylene on multiwall carbon nanotubes has been investigated. The effect of contact time, pH, initial concentration of trichloroethylene and temperature on its adsorption were investigated. Adsorption isotherms and related constants were also determined. Results showed that contact times to reach equilibrium changed from 30 min (for 150 μg/L initial concentration) to 10 min (for 600 μg/L concentrations) at 25 °C; the equilibrium times in 40°C were 40 min and 15 min, respectively. Multi-wall carbon nanotubes showed to act as a good adsorbent for TCE in a wide range of pH=(3-9). For pH>9, adsorption decreased due to ionization of oxygen-containing groups. Adsorption test results revealed that TCE adsorption on the studied adsorbents could be better described by Freundlich isotherm.

  • S. Beena Lahari, P. King, V. S. R. K. Prasad Page 383

    The adsorption study on removal of copper metal from aqueous solution using untreated marine green algae namely Chaetomorpha Antennina sp. was carried out under various experimental conditions. The effects of contact time, pH of the solution, average biosorbent particle size, biosorbent dosage and initial concentration of metal ion have been investigated by following the batch adsorption technique. 30 minutes of biosorption time was found to be sufficient to reach equilibrium rate of sorption for copper ion. The rate of copper removal was directly correlated to biomass amount and contact time. Biosorption of metal ion was pH dependent and the results indicated the optimum pH for the removal of copper as 6.0. The highest biosorption capacity was found to be 25.78 mg of metal ion per gram of biosorbent at initial concentration of 20 mg/L copper ion and increased for higher initial concentrations. The biosorption capacity increased with increase in the amount of biosorbent used for removal. Adsorption data was modled with Freundlich, Langmuir, Redlich- Peterson and Dubinin–Radushkevich adsorption isotherms. Isotherm studies showed that the data best fitted with the Langmuir isotherm model. The kinetic data corresponded well with the pseudo-first order equation, suggesting that the biosorption process is presumably chemisorption.

  • K. Naddafi, H. Jabbari, M. Hoseini, R. Nabizadeh, M. Rahbar, M. Younesian Page 393

    The wide use of subway system by citizens underlines the importance of hygienic issues including indoor air pollution in these public places especially in metro stations. The aim of this study was to investigate the bacterial contamination in indoor and outdoor air of two metro stations (Imam Khomeini and Sadeghiyeh stations) in Tehran subway system. In this cross sectional study, three sampling locations were selected in each station. Also, sampling was conducted in indoor air of two types (old and new) of trains. The range of bacterial colony count was 35-1501 CFU/m3. Maximum and minimum bacterial contamination levels in Imam Khomeini and Sadeghiyeh platform stations were averagely 1073 CFU/m3 and 242 CFU/m3, respectively. 14 bacterial species and genera were isolated; among them the dominant species were Staphylococcus epidermidis, Micrococcus luteus and Bacillus spp. Results showed that bacterial concentrations in indoor air were higher than the outdoor air; also the bacterial counts correlated significantly with number of the passengers (p<0.001) and air temperature (p<0.001).