فهرست مطالب

Advances in Environmental Technology - Volume:4 Issue: 3, 2019
  • Volume:4 Issue: 3, 2019
  • تاریخ انتشار: 1397/10/15
  • تعداد عناوین: 6
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  • Mohsen Kojuri, Fatemeh Ardestani * Pages 139-147
    Microbialbiodegradation is known as an effective and harmless method to overcome environmental pollution with oil hydrocarbon. Some bacterial species were isolated from the Sarvestan oilfields (Iran, Fars province), then identified and applied for oil hydrocarbon decomposition. A carbon-free minimum medium (CFMM) containing 1% crude oil was used to isolate bacteria through incubation at 30°C in the dark at 200 rpm for 7 days. Different methods were used to identify the  hydrocarbon oil decomposing bacteria: gram staining, squalene hydrolysis, catalase, production of arginine dihydrolase, gelatin liquefaction, hydrogen sulfide production, levan production, methyl red, oxidase, nitrite reduction, oxidative/fermentative, starch hydrolysis and Tween-80 hydrolysis tests. Nine different oil decomposing bacterial species were isolated. All the species grew well at 28 and 35°C, while four isolates containing of Bacillus sp. SA13, Pantoea sp. SA1112, Pseudomonas aeruginosa sp. SA21, and Bacillus sp. SA23 were capable of growing in a temperature of up to around 42°C. The minimum salt tolerance for isolates, except for Enterobacter sp. SA711, was 8%; Bacillus sp. SA212 had the highest tolerance of 15% sodium chloride. Acinetobacter sp. SA172, Enterobacter sp. SA711, Pseudomonas sp. SA75, Bacillus sp. SA212 and Bacillus sp. SA23 had the most growth rate in the CFMM. The highest percentages of oil removal obtained were 89% for Enterobacter sp. SA711, 86% for Acinetobacter sp. SA172, and 68% for Pseudomonas sp. SA75. The three isolated bacterial strains from the contaminated soil of the Sarvestan area had a good ability to degrade oil hydrocarbon. Therefore, they could be used commercially for the bioremediation of this region.
    Keywords: Biochemical test, Biodegradation, Contaminated soils, Oil removal bacteria
  • Hakimeh Sharififard * Pages 149-154
    The adsorption ability of activated carbon, chitosan, and chitosan/activated carbon composite for cadmium separation from aqueous solution was analyzed via statistical physical modeling. The equilibrium data were analyzed by Langmuir, Hill, double layer model, and the multi-layer model with saturation isotherm models. Results showed that the multi-layer model with saturation could well describe the data. The number of the adsorbate ions per site, the receiver site density, the number of formed layers, and the energies of adsorption relative to the different layers were estimated by numerical simulation. Results showed that the chitosan/activated carbon has higher receiver site density and the total amount of adsorbed ions than that other two adsorbents. Results showed that the cadmium adsorption onto activated carbon/chitosan composite is a monolayer and exothermic process. With increasing temperature, the amount of cadmium adsorption decreases due to the fact that the number of receiver adsorption sites decreases. Also, the statistical physics modeling indicated the geometry of cadmium ions adsorbed onto the adsorbent surface is parallel.
    Keywords: Cadmium, Adsorption, Statistical physics modeling, Multi-layer model with saturation
  • Majid Pirooz, Neda Akbari, Mehdi Kamali, Davoud Biria * Pages 155-161
    This study investigated different methodsof controlling the fat, oil and grease (FOG) in sewer systems. A comprehensive control program wasdevelopedfor the city of Mashhad (Iran) to maintain its sewer system and prevent blockages. The control program consisted of three parts: 1) fat, oil and grease source control, 2) sewer system modification and 3) preventive maintenance. This program includedguidelinesfor food service establishments, which are the majorsources of (FOG). Food service establishments must implementbetter management practices to reduce (FOG)from entering the facility drain and install grease removal devices.As a part of preventive cleaning, theperformance of several surfactants was evaluated as a cleaning agent. A 50:50 mixture (10 v. % in water) of two industrial surfactants, one containing monoethyl amine and sulfonated lauryl alcohol and one containing nonylphenolethoxylate and potassium hydroxide,had the best performance and removed 80 % of the fat. Response Surface Methodology was used to determine the optimum conditions for the surfactant.The optimum conditions were acontact time of 36 h, shaking rate of 30 rpm andsurfactant concentration of 12.5%.The second part of the program consisted ofremoving dead zones and increasing wastewater velocity in the sewer lines to enhance thehydraulic condition of thesewer system and decrease fat deposition.Finally, a detailed and well-defined control program couldsolve FOG problems in sewer systems.
    Keywords: Sewer system maintenance, Fat Oil, Grease, Control program, Chemical cleaning, Mashhad city
  • Abdollah Mohammadpoor, Masoomeh Mirzaei *, Alireza Azimi, Mostafa Tabatabaee Ghomshe Pages 163-174
    Amine solvents are extensively used on an industrial scale for removing carbon dioxide (CO2). The presence of some additives in amine solvents has a desirable effect on CO2 absorption kinetics and also improves the absorption process. In this study, graphene oxide (GO) nanoparticles and the anionic surfactant sodium dodecyl sulphate (SDS) were used as additives to the amine solvent. The number of CO2 moles that were used (ng), the values of the diffusion coefficient (DAB), and the mass transfer coefficients of CO2 gas absorption in the amine solvent (Kc) were determined. Furthermore, the effect of the additives on the kinetics of CO2 gas absorption in the amine solvent was investigated. The results showed that mass transfer coefficients increased with a decrease in pressure and an increase in temperature as well as in the SDS and GO concentrations. The values of the mass transfer coefficient under different conditions varied between 0.0311 and 0.0587 cm/s. The molecular diffusion coefficient of CO2 in the amine solvent increased from 0.000025 to 0.000287 cm2/s with decreases in the pressure and with increases in the temperature and increases in concentrations of additives. The laboratory data were statistically analyzed via Design-Expert software using response surface experiment design and a historical method. A mathematical relation was proposed to estimate the mass transfer coefficients. Moreover, a mathematical relation was introduced to predict the molecular diffusion coefficient of CO2 in the amine solvent.
    Keywords: Carbon Dioxide, absorption kinetics, nanoparticle, anionic surfactant, amine solvent
  • Milad Hallajiqomi, Mohsen Mehdipour Ghazi *, Farshad Varaminian Pages 175-182
    photocatalytic reactor was tested in the degradation of diazinon in water using photocatalyst clinoptilolite zeolite-silver. The photocatalyst clinoptilolite zeolite-silver was synthesized using a microwave energy technique. The influence of AgO in the photocatalytic reactor was investigated for diazinon treatment. The prepared photocatalyst was authenticated by X-Ray Diffraction (XRD), for Field Emission Scanning Electron Microscope (FESEM), Brunner-Emmet-Teller (BET), and Diffuse Reflectance Spectroscopy (DRS) analysis methods. Every one of the mixtures was analyzed using XRD, and the three distinctive peaks (2Ɵ = 9.84, 11.17, and 22.35) of clinoptilolite were chosen for which the calculations of the peak intensity summation were done.  The experiments appraised the influence of various empirical factors, e.g., pH, photocatalyst dosage, initial diazinon, and irradiation time on the degradation efficiency. The results showed that the optimum conditions for diazinon degradation were a pH of 9, photocatalyst dosage of 1 g/L and irradiation time of 120 min. The point of zero charge (pzc) of the photocatalyst clinoptilolite zeolite-silver, the point when the surface charge density is zero, was identified to be 8. This excellent catalytic ability was mainly attributed to the hybrid effect of the photocatalyst and adsorbent.
    Keywords: Clinoptilolite Zeolite-Silver, Diazinon, Microwave Irradiation, Photocatalytic degradation, photocatalytic reactor
  • Erfan Ziarifar, Rahbar Rahimi *, Morteza Zivdar Pages 183-186
    This paper describes the feasibility of replacing a sulfur-based additive with the waste by-product disulfide oil (DSO) in steam cracking for the production of olefin. The objective of adding this substance is to reduce coke formation, and consequently, prevent its formation on the inner walls of the reactor and heat exchanger. It is reported that dimethyl sulfide (DMDS) is a source of hydrogen sulfide, and it is hydrogen sulfide that minimizes coke formation, even though the mechanism is not clear. Disulfide oil is a waste material in gas refineries and a source for hydrogen sulfide production; therefore, it makes sense to evaluate its efficacy in minimizing CO production and coke formation during olefin production. Therefore, pilot plant runs were performed to evaluate its feasibility. By using disulfide oil, the total sulfur content of the pyrolysis gasoline will change and be equal to 26.89 mg/L for the unit with a capacity production of 18000 kg/hr. This action not only provides a low-price resource that inhibits coke deposition in olefin plants but also curtails the emission of hydrogen sulfide into the environment.
    Keywords: Thermal cracking, Oelfin plant, Disulfide oil, Environmental hazards, Coke inhibitor