فهرست مطالب

Environmental Health Science and Engineering - Volume:8 Issue:2, 2011
  • Volume:8 Issue:2, 2011
  • تاریخ انتشار: 1390/04/04
  • تعداد عناوین: 11
  • M. H. Ehrampoush, Gh. Ghanizadeh, M. T. Ghaneian Page 101
    The aim of this study was to determine the equilibrium and kinetics adsorption of reactive red 123 dye (RR 123) from aqueous solution with chicken's eggshell as an adsorbent. The initial concentrations of reactive red 123 dye were selected in the range of 25 and 50 mg/L. The target adsorbent was prepared in laboratory conditions and pulverized by ASTM standard sieves. Measurement of the adsorbent surface area was carried out via Brunauer-Emmett-Teller isotherm. The experimental data were analyzed with Langmuir, Freundlich and Temkin isotherm models. The results showed that the calcium components were the main constituents of eggshell (around 95% Ca). The experimental adsorption isotherm was in good concordance with Langmuir and Freundlich models (R2>0.90) and based on the Langmuir isotherm the maximum amount of adsorption (qmax) was 1.26 mg/g. Increase of the eggshell dose and the solution temperature beyond 45◦C led to decrease of the adsorbed dye per mass unit of the adsorbent, but increase of the solution pH up to 9 led to improvement of dye adsorption. The kinetic studies revealed that the adsorption of reactive red 123 was rapid and complied with pseudo second-order kinetic (R2= 0.99), with the kinetic constant of 0.02 g/mg.min.
  • A. Shahtalebi, M. H. Sarrafzadeh Page 109
    Separation of amoxicillin from pharmaceutical wastewater by nanofiltration (NF) membrane has been investigated in this study. For this purpose a membrane system including a polyamide spiral wound NF membrane was evaluated for the treatment of amoxicillin wastewater. The effects of operating conditions such as flow rate, pressure and concentration of amoxicillin and COD in the feed, on the efficiency of the membrane were evaluated. The permeation flux and rejection of amoxicillin and COD were the criteria for this evaluation. The rejection of the amoxicillin by the selected NF membrane was adequate and in most cases exceeded 97% whereas COD reached a maximum of 40% rejection and permeation flux was over 1.5 L/min.m2. The rise in pressure enhanced the transport rate of the solvents. Permeation flux of the NF membrane increased with increasing flow rates. Experimental data also indicated that concentration polarization existed in this membrane separation process. The stable permeation flux and high rejection of amoxicillin indicated the potential of NF for the recovery of amoxicillin from the pharmaceutical wastewater
  • D. Rabbani, H. Hooshyar Page 117
    Application of solar energy for wastewater treatment has shown to have the least negative effects and costs. This experimental research was carried out in pilot-scale on the effluent of the extended aeration activated sludge wastewater treatment system in Kashan. The plant is located at the Kashan University of Medical Sciences campus and receives about 100 m3/d sewage from official and residential building blocks. In this study thermal disinfection of the effluent in 55 ºC for 2 hours using flat plat solar collector (FPSC) was investigated. During the study in the beginning of every week, one day was selected randomly and the pilot was run. The pilot influent temperature was the same as ambient air throughout the day. If the liquid temperature within the pilot increased above 55 ºC, a thermostatic valve opened. Passed liquid was maintained for 2 hours in this temperature. Whenever the volume of disinfected effluent was measurable fecal MPN test and Nemathoda eggs count-up were done according to the Standard Methods and Leeds-II directions, respectively. In 200 days from April to November the geometric mean of fecal coliform never exceeded the WHO guideline (1000 MPN/100mL), but in 5 days (21%) it exceeded the Iranian standard (400/100mL). Mathematical mean of Nemathoda eggs was less than 1 per liter (Engelberg Index) persistently. The mean of hydraulic loading rates was calculated 83.25 L/d m2 while it decreased to 41.85L/d.m2 in the days without thermal reclamation.
  • A. Kamkar, Gh. R. Jahed Khaniki, S. A. Alavi Page 123
    Contamination of milk and dairy products to aflatoxin M1 is a risk for human and it can be a public heath concern. The aim of this study was to evaluate the presence of aflatoxin M1 in raw milk samples produced in Ardebil City (Iran) by ELISA (Enzyme Linked Immuno Sorbent Assay) technique. 122 samples of raw milk were collected from milk collecting centers and dairy plants in the region and aflatoxin M1 contamination was detected in all of milk samples. The mean concentration of aflatoxin M1 was 40.01ng/L and 14.75 percent of the samples had higher levels than the maximum recommended limits by ISIRI, European Community and Codex Alimentarius. With a view of the fact that milk is used by all the age groups including infants and children in the city of Ardebil, it is necessary to apply an ideal recommended limit to minimize the health hazard from aflatoxin M1 contamination in milk. Application of Good Agricultural Practices and Good Veterinary Practices by agriculture and also the Hazard Analysis and Critical Control Points (HACCP) system as a draft code of practice for preharvest and postharvest control of dairy cow's feed and in milk and dairy products processing is effective.
  • S. A. R. Mousavi, A. H. Mahvi, S. Nasseri, Sh. Ghaffari Page 129
    This study investigates the degradation of Linear Alkylbenzene Sulfonate (LAS) in aqueous solution using Fenton's process in a batch reactor (at pH = 3 and 25°C). Experiments were carried out to survey the effects of the amounts of ferrous sulfate (FeSO4.7H2O) and hydrogen peroxide (H2O2) on the LAS and COD removal. Central composite design and response surface methods were used to optimize the Fenton oxidation process through examination of three independent operating variables namely oxidant dose (H2O2), catalyst dose (Fe+2) and reaction time., hydrogen peroxide dose ranging from 150 to 750 mg /L and Fe+2 concentration in the range of 10 -130 mg /L were selected to be examined at different reaction times between 20 and 80 minutes. Models were developed and results shows that the oxidation capacities of H2O2 /Fe+2 were highly dependent on the concentration of H2O2 and Fe+2. Satisfactory decay rates of LAS to lock up biodegradable concentration level were obtained, and in the case for oxidation of 200 mg /L LAS, the optimum values were achieved at 600 and 130 mg/L for H2O2 and Fe+2, respectively.
  • Gh. R. Roshan, F. Khoshakh Lagh, Gh. Azizi, H. Mohammadi Page 139
    The present research intends to show the effect of global warming on the trend and patterns of temperature in Iran. The study has been divided into two primary parts, the first of which is an analysis of the country's temperature trend using the following data measures: the minimum, maximum, and mean seasonal night temperature (the minimum temperature) components, the day temperature (the maximum temperature) component and the mean daily temperature component. This data is specific to the time frame 1951 to 2005 and it was obtained from 92 synoptic and climatology stations around the country. The second part of this research involved simulating and forecasting the effects of global warming on temperature values under conditions in which greenhouse gases have increased. For analyzing these simulations and forecasts the MAGICC SCENGEN model was used and different climate change scenarios were taken into consideration. The results are quite interesting. In the analysis of the country's current temperature trend and in the forecastings, specifically related to time, a significant temperature increase was observed during the summer months. Also, with regard to altitudinal levels, it was evident that stations at higher altitudes show a more significant increase in daily and mean daily temperatures. Taking into account the output mean of the different climate change scenarios, the temperature simulations show a 4.41° C increase in Iran's mean temperature by 2100. Most of these temperature increases would occur in the southern and eastern parts of Bushehr, certain coastal regions of the Persian Gulf, eastern and western parts of Fars, Kohgilooye, Boyerahmad, southern parts of Yazd, as well as southern and southeastern parts of Esfahan
  • M. Sen, M. Ghosh Dastidar Page 153
    Chromium is one of the toxic heavy metals which exists in nature as stable hexavalent and trivalent forms. The hexavalent form of chromium is more toxic than trivalent chromium as it persists indefinitely in the environment complicating its remediation. The conventional physical and chemical treatment techniques used for the removal of Cr(VI) are expensive and highly energy intensive, moreover they produce harmful by-products, ultimate disposal of which again causes secondary pollution. Removal of Cr(VI) from aqueous solution using biological sources as biosorbent has assumed advantageous over the existing conventional physico-chemical techniques for the treatment of metal contaminated wastes. The present batch biosorption study was undertaken with an aim to examine the Cr (VI) removal potential of the resting cells of Fusarium solani (isolated from soil) from aqueous solution. The specific Cr (VI) removal decreased with increase in pH and increased with increase in initial Cr(VI) concentration, up to 500 mg/L. The specific Cr(VI) removal remained almost constant by increasing biomass concentration from 2.4 to 5.2 g/L. The studies also carried out by using the resting cells obtained from various stages of growth and the maximum specific Cr(VI) removal (60 mg/g) was achieved at 500 mg/L initial Cr(VI) concentration and by using cells (36 h old). The Langmuir adsorption isotherm constants, Q0 and b were observed to be 57.1 mg/L and 0.06 l 1/mg, respectively.
  • R. Dehghanzadeh, H. Aslani, A. Torkian, M. Asadi Page 159
    Considering concurrent use of styrene and acrylonitrile as raw materials in the production of synthetic resins and plastic and their associated differences in physiochemical properties and biodegradability, our experiments were conducted in a three-stage downflow bench-scale biofilter to study the potential suppressive effects of acrylonitrile on styrene removal. A Mixture of yard waste compost and shredded plastics and activated sludge was used as bed media. Gas phase concentration of styrene and acrylonitrile was determined via gas chromatographic analysis. Under steady-state conditions, maximum elimination capacity of styrene and acrylonitrile was 44 and 120 g/m3 h, respectively. The effect of moisture was very significant in reducing the specific adsorptive capacity (μg/g of bed media) of styrene and acrylonitrile. The bed media with 60% moisture content lost styrene absorption capacities by more than one order of magnitude when compared to dry media. The existence of water increased the absorption capacity of medium for acrylonitrile about 95%. Styrene elimination capacity of the biofilter during co-treatment was less as compared to pure styrene biodegradation indicating the likelihood of inhibitory kinetics. Introduction of acrylonitrile into the air stream reduced elimination capacity of styrene to 103 g/m3 h. The adverse impact on removal rate of acrylonitrile due to the presence of styrene in the gas stream was minimal. Carbon-equivalent removal for the system amounted to about 85 g C/m3 h at empty bed retention time of 120 s.
  • G. R. Soltanian, M. Havaee Behbahani Page 169
    Metal Oxides (Titania TiO2, and Calamine (ZNO)) have been used as tertiary treatment for Refinery Effluent treatment and wastewaters to comply with the regulatory discharge limits and to oxidize persistent compounds that had not been oxidized in the biological treatment. The wastewater was provided by the Bandar Abbas Refinery. Although BOD removal is high in this plant, a residual and persistent COD (Chemical Oxygen Demand), besides a somewhat high phenol content remains. Three catalysts were tested TiO2 (Aldrich), ZnO (Aldrich), and TiO2 (P25, Degussa) by the UV radiation, the third being the most active. The optimized conditions obtained with an experimental design were 3.0 (g/L) TiO2 and pH=6.3. The use of hydrogen peroxide (H2O2) showed no beneficial effect. Removal of 93% of phenols, 56% of dissolved organic carbon (DOC), and more than 50% of oil and grease (OG) were achieved in the catalytic process with UV radiation, improving the quality of the treated wastewater.
  • A. R. Rahmani, H. R. Ghaffari, M. T. Samadi Page 175
    The present study was conducted for Arsenic (III) removal, one of the most poisonous groundwater pollutants, by synthetic nano and micro size zerovalent iron (n-mZVI). Batch experiments were performed to investigate the influence of As (III), nZVI and mZVI concentration, pH of solution and reaction time on the efficiency of As (III) removal by Fe0 particles. Nano ZVI was synthesized by reduction of ferric chloride by sodium borohydrid. Scanning Electron microscope and X-Ray diffraction were used to determine particle size and characterization of produced nanoparticles. Results showed up to 99.9% removal efficiency for arsenic (III) that was obtained by nZVI dosage of 1 g/L at equal time of 10 min and pH=7. The maximum removal efficiency by mZVI obtained in initial arsenic concentration of 1 mg/L and mZVI dosage of 10 g/L after 120 min. and pH=7. It could be concluded that the removal efficiency was enhanced with increasing n-mZVI dosage and reaction time, but decreased with increasing of arsenic concentration and pH for both nano and micro sized ZVI. Nano ZVI presented an outstanding ability to remove As (III) due to not only a high surface area and low particle size but also to high inherent activity.
  • M. R. Samarghandi, S. Azizian, M. Shirzad Siboni, S. J. Jafari, S. Rahimi Page 181
    The removal of divalent nickel from aqueous solutions on modified holly sawdust was studied at varying contact times, pH, initial divalent nickel concentrations and adsorbent dose. Results showed the removal efficiency by increasing of pH increased and decreased with initial nickel divalent concentration. By increasing pH from 2 to 12 (equilibrium time= 240 min, adsorbent dose= 0.6g/100 mL, divalent nickel concentrations= 60 mg/L), the removal efficiency increased from 17.47 % to 81.76 %. Also removal efficiency was decreased from 98 % to 19.3 % by increasing of initial divalent nickel concentrations from 20 mg/l to 100 mg/L. Also the results showed the removal efficiency was increased by increasing of adsorbent dose and contact time. By increasing of adsorbent dose from 0.2 g/100CC to 1 g/100CC, the removal efficiency increased from 32.78% to 99.98%. The removal efficiency increased from 34.7% to 83.67% by increasing of contact time from 5 min to 240 min. Experimental equilibrium and kinetics data were fitted by Langmuir and Freundlich isotherms and pseudo-first-order and pseudo-second-order kinetics models, respectively. The results show that the equilibrium data follow Langmuir isotherm and the kinetic data follow pseudo-second-order model. The obtained maximum adsorption capacity was 22.47 mg/g at a pH 7. The results show that the modified holly sawdust can be used for the treatment of aqueous solutions containing nickel as a low cost adsorbent.