Publications by authors named "Abbas Rezaee"

25 Publications

  • Page 1 of 1

The influence of combined low-strength ultrasonics and micro-aerobic pretreatment process on methane generation and sludge digestion: Lipase enzyme, microbial activation, and energy yield.

Ultrason Sonochem 2021 Mar 22;73:105531. Epub 2021 Mar 22.

Research Center for Environmental Health Technology, Iran University of Medical Sciences, Tehran, Iran; Department of Environmental Health Engineering, School of Public Health, Iran University of Medical Sciences, Tehran, Iran.

Low-frequency ultrasonics is a potential technology to reduce the hydrolysis phase period in anaerobic digestion process. In this study, theinfluence of combined low frequency ultrasonics and micro-aerobic (MA) pretreatment on sewage sludge solubilization, enzyme activity and anaerobic digestion were assessed. Initially, the effect of ultrasonic density (0.012, 0.014, 0.016, 0.018, 0.1, 0.12 and 0.14 W/mL) and irradiation time (1, 3, 5, 8, 9, 10 and 12 min) of 20 kHz frequency waves were investigated. Accordingly, the effect of micro-aerobic pretreatment (Air flow rate (AFR) = 0.1, 0.2, 0.3 and 0.5 VVM) within 20, 30, 40.48 and 60 h were examined. In addition, the effect of combined pretreatment on COD solubilization, lipase enzyme activation, ATP, percentage of live bacteria and methane gas production during the anaerobic process were examined. The results showed that the highest lipase activity (14.9 Umol/mL) was obtained under the effect of ultrasonic density of 0.1 W/ml within 9 min. The highest solubilization (65%) was observed under optimal micro-aerobic conditions: AFR = 0.2 (VVM) and micro-aerobic time: 40 h. Combined ultrasonic and micro-aerobic (US + MA) pretreatment increases the solubilization (70%), microbial activity (2080%) and lipase enzymatic activity (129%) compared to individual pretreatment. The Biogas production during anaerobic digestion pretreated with combined methods increased by 193% compared to the control, while the elevated values of biogas production in reactors pretreated by ultrasonic and micro-aerobic pretreatment alone were observed to be 101% and 165%, respectively. The net energy in reactor with the combined pre-treatment methods was calculated to be 1.26 kWh, while this value for control, pretreated ultrasonic and micro-aerobic reactors were obtained to be 0.56, 0.67 and 1.2 kWh, respectively.
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http://dx.doi.org/10.1016/j.ultsonch.2021.105531DOI Listing
March 2021

Removal of aspirin from aqueous solution using electroactive bacteria induced by alternating current.

Environ Sci Pollut Res Int 2021 Jan 16. Epub 2021 Jan 16.

Department of Environmental Health Engineering, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.

This study aims to improve bacterial laccase enzyme activity (LEA) and dehydrogenase activity (DHA) affecting acetylsalicylic acid (ASA) biodegradation using an alternating current (AC). A microbial consortium was inoculated in an electroactive bioreactor supplied with an AC by a function generator under operating conditions of amplitude (AMPL) = 2-10 peak-to-peak voltage (V), optical fiber splice tray (OFST) = 0.1 V, and sine wave frequency = 10 Hz. The obtained results revealed that at an applied voltage of 8 V and an OFST of 0.1 for 12 h, the maximum bacterial LEA and DHA were 30.6 U/mL and 75.5 micro grTF/cm.gr biomass; respectively. Cell viability and permeability were equal to 95.7% and 0.3%; respectively, at the voltage of 8 V. Moreover, liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) analyses showed that by-products had lower intensity at 8 V compared with that of 2 V voltage. Finally, the results demonstrated an optimum applied voltage of the AC, which could stimulate and promote bacterial LEA and DHA. Therefore, an electroactive bioreactor supplied with an AC can be a novel system for stimulation of enzyme activities in the process of ASA biodegradation.
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http://dx.doi.org/10.1007/s11356-020-11365-zDOI Listing
January 2021

Electrocatalytic ozonation process supplemented by EDTA-Fe complex for improving the mature landfill leachate treatment.

Chemosphere 2021 Jan 13;263:127858. Epub 2020 Aug 13.

Department of Environmental Health, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran. Electronic address:

The present study was to enhance catalytic ozonation process (COP) using ferric (Fe)- ethylenediaminetetraacetic acid (Fe-EDTA) integrated with an electrocoagulation (EC) process for landfill leachate pretreatment. For this purpose, the effect of operating parameters such as ozone and Fe-EDTA concentrations, current, initial pH, and reaction time were investigated. The findings revealed that the EC process and single ozonation process (SOP) could alone reduce chemical oxygen demand (COD) in landfill leachate by 23% and 39%; respectively. Moreover, integration of both processes at 100 mA current, 400 mg h ozone concentration, and 3 h reaction time could significantly improve COD reduction to 70%. As well, current efficiency and ozone consumption in the proposed system could considerably develop compared with EC process and SOP. The integrated electro-catalytic SOP using Fe-EDTA could be operated at neutral pH value, which the COD removal efficiency was obtained 79.7%. Subsequently, biochemical oxygen demand (BOD)/COD ratio of effluent increased to 0.64. Examining pseudo-first-order and pseudo-second-order kinetics, it was realized that constant rate in the system had augmented. These results also indicated that the modified process using Fe-EDTA was a promising landfill leachate pretreatment technique that could significantly enhance COD removal efficiency and BOD/COD ratio, and ultimately decrease time and sludge production.
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http://dx.doi.org/10.1016/j.chemosphere.2020.127858DOI Listing
January 2021

Perspectives on microbial community in anaerobic digestion with emphasis on environmental parameters: A systematic review.

Chemosphere 2021 May 16;270:128618. Epub 2020 Oct 16.

Research Center for Environmental Health Technology, Iran University of Medical Sciences, Tehran, Iran; Department of Environmental Health Engineering, School of Public Health, Iran University of Medical Sciences, Tehran, IR, Iran. Electronic address:

This paper review is aiming to comprehensively identify and appraise the current available knowledge on microbial composition and microbial dynamics in anaerobic digestion with focus on the interconnections between operational parameters and microbial community. We systematically searched Scopus, Web of Science, pubmed and Embase (up to August 2019) with relative keywords to identify English-language studies published in peer-reviewed journals. The data and information on anaerobic reactor configurations, operational parameters such as pretreatment methods, temperature, trace elements, ammonia, organic loading rate, and feedstock composition and their association with the microbial community and microbial dynamics were extracted from eligible articles. Of 306 potential articles, 112 studies met the present review objectives and inclusion criteria. The results indicated that both aceticlastic and hydrogenotrophic methanogenesis are dominant in anaerobic digesters and their relative composition is depending on environmental conditions. However, hydrogenotrophic methanogens are more often observed in extreme conditions due to their higher robustness compared to aceticlastic methangoens. Firmicutes and Bacteroidetes phyla are most common fermentative bacteria of the acidogenic phase. These bacteria secrete lytic enzymes to degrade organic matters and are able to survive in extreme conditions and environments due to their spores. In addition, among archaea Methanosaeta, Methanobacterium, and Methanosarcinaceae are found at high relative abundance in anaerobic digesters operated with different operational parameters. Overall, understanding the shifts in microbial composition and diversity as results of operational parameters variation in anaerobic digestion process would improve the stability and process performance.
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http://dx.doi.org/10.1016/j.chemosphere.2020.128618DOI Listing
May 2021

Effects of Low Frequency-Low Voltage Alternating Electric Current on Apoptosis Progression in Bioelectrical Reactor Biofilm.

Front Bioeng Biotechnol 2020 22;8. Epub 2020 Jan 22.

Department of Environmental Health, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.

Bioelectrochemical systems have undergone several modifications to promote the enzymes or pathways used to reduce the energy required for microbial metabolism. Changes in dominant bacteria, population, and growth rates occur when an electric current is applied intermittently. Applying electricity to bioelectrical reactor (BER) biofilms can either stimulate cells or lead to cell death; therefore, determining the applied voltage range that leads to viable and stimulated bacteria is crucial. We investigated the progression of apoptosis induced by a low frequency-low voltage alternating electric current (AC) in a BER biofilm and found that biofilms on carbon cloth (CC) and stainless steel (SS) 304 electrodes had pH values of 8.67. The pH of the biofilms increased by two compared to that of the inoculant bacteria mass. Furthermore, the Henderson-Hasselbalch equation reveals that the compositions of cell walls of the biofilms that formed on the CC and SS304 electrodes are very similar. In contrast, the CC and SS304 biofilms differ from the inoculant biomass without the influence of an AC field; this indicates that there are differences in the compositions of the cell walls in the present bacteria. Fourier transform infrared spectroscopy was used to compare spectra of the biofilms with that of the inoculation mass, and there were differences in shape and absorbance intensity, indicating variability in the composition, and quantity of each individual biofilm component. In addition, the dehydrogenase activity (DHA) content varied under different applied voltages; the highest DHA was obtained at 8 Vpp. A flow cytometry analysis showed a relatively low number of apoptotic cells (10.93 ± 5.19%) for the AC amplitudes studied. Thus, a low voltage-low frequency AC likely induces significant changes in bacterial metabolic activity but causes no significant change in their viability.
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http://dx.doi.org/10.3389/fbioe.2020.00002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6987302PMC
January 2020

Minimization of hazardous sludge production using a bioelectrochemical system supplied by an alternating current electric field.

Bioelectrochemistry 2020 Apr 31;132:107446. Epub 2019 Dec 31.

Department of Environmental Health Engineering, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran; Department of Environmental Health Engineering, Sirjan School of Medical Sciences, Sirjan, Iran.

In the present study, minimization of hazardous bio-sludge production was investigated using a bioelectrochemical system supplied by an alternating current electric field and supplemented with phenol as a cabon source. The experiments were conducted in an air-conditioned bioreactor and at neutral pH value. Moreover, steel wool and carbon cloth were utilized as electrodes in the bioelectrochemical system. The experiments were operated in an air-conditioned bioreactor at 25 ℃ and a neutral pH value with carbon to nitrogen (C/N) ratio of 0.5-6. The results obtainedshowed that complete phenol electro-biodegradation occurred at a C/N ratio ofa frequency of 5 Hz, and 0.4 peak-to-peak voltage (Vpp) over 2 h.Besides, sludge production and sludge yield were obtained at the C/N ratio of 0.5-6 by 200-382 mg VSS/g COD and 82-89.4 mg TSS/g COD, respectively. Ultimately, the C/N ratio of 1 seemed to be optimum for microbial growth with the phenol biodegradation efficiency of 99.9% as well as the lowest sludge production. These results demonstrated that the proposed bioelectrochemical system supplied by low-frequency and low-voltage electric current could reduce hazardous sludge production.
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http://dx.doi.org/10.1016/j.bioelechem.2019.107446DOI Listing
April 2020

Electro-catalytic ozonation for improving the biodegradability of mature landfill leachate.

J Environ Manage 2020 Jan 8;254:109811. Epub 2019 Nov 8.

Department of Environmental Health, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran. Electronic address:

Landfill leachate contains complex, resistant, and diverse compounds that are considered as an environmental health problem. This study aims to investigate the efficacy of integrated homogeneous catalytic ozonation and electrochemical process for improving the biodegradability of landfill. This experimental study was conducted on real landfill leachate on the laboratory scale. The variables were current density (O/HO-42.1 mA/cm), ozone concentrations (100-400 mg/h), the initial pH (3-9), and the reaction times (1-6 h). The optimum operating condition was obtained at 1.42 mA/m, 400 mg/h of ozone concentration, initial pH of 3, during 3 h. In the proposed integrated catalytic ozonation-electrochemical process, the chemical oxygen demand (COD) and biochemical oxygen demand (BOD) concentrations were removed to 3381.9 and 1521.8 mg/L, respectively. Under the optimum condition, the biodegradability index increased from 0.27 to 0.45. The results showed that the electro-catalytic ozonation process has a significant effect on the biodegradability index and could improve the removal efficiency of landfill leachate treatments.
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http://dx.doi.org/10.1016/j.jenvman.2019.109811DOI Listing
January 2020

Effect of isoelectric point on cheese whey wastewater treatment using a microbial electrochemical system.

Bioelectrochemistry 2019 Dec 28;130:107200. Epub 2018 Aug 28.

Department of Chemistry, Surface Chemistry Research Laboratory, Iran University of Science and Technology, Tehran, Iran.

In this study, a microbial electrochemical system (MES) was employed to investigate the effect of isoelectric point (IEP) on cheese whey wastewater treatment. The experiments were carried out in a bioreactor equipped with a semicircular carbon cloth and stainless steel electrodes as anode and cathode, respectively. The effects of IEP, whey protein concentration, electrical current, and time were studied. The IEP of the whey protein was determined at pH 5.9. The optimum electrical current was obtained at 6 mA for synthetic cheese whey wastewater. The results of rotary exponential doping showed that the third structure of proteins chenges to the second structure at the IEP. The highest protein removal (98%) was obtained at pH 6. The results showed that 76%, 83%, and 98% protein removal were achieved at 2, 4, and 8 h, respectively.
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http://dx.doi.org/10.1016/j.bioelechem.2018.08.004DOI Listing
December 2019

Microbial electrochemical system for the phenol degradation using alternating current: Metabolic pathway study.

Bioelectrochemistry 2019 Dec 5;130:107230. Epub 2018 Dec 5.

Department of Environmental Health, School of Public Health, Iran University of Medical Sciences, Tehran, Iran.

The present study was conducted to investigate the effect of alternating current (AC) on phenol removal in a microbial electrochemical system (MES) and determine its by-products. The bioreactor used for this purpose operates in the batch mode supplied with an AC power supply. The factors stimulating this process including frequency, applied voltage, duty cycle, carbon to nitrogen ratio, and the initial phenol concentration were investigated. The optimum operating conditions of the bioreactor were obtained at 5 Hz frequency, 0.4 peak-to-peak voltage (Vpp), C = 100 mg.L phenol, pH = 7, C/N = 1, and the sine wave. Phenol was completely degraded under the optimum operating conditions for 2 h. The GC-MS analysis showed the presence of carboxylic acid, oxalic acid, and propionic acid. It was observed that the generated by-products are non-toxic and phenol is completely removed to nontoxic compounds. The results show that under optimum conditions, using an alternating current, the proposed system generated low-hazard byproducts with a low energy consumption.
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http://dx.doi.org/10.1016/j.bioelechem.2018.12.002DOI Listing
December 2019

Metabolic activity and pathway study of aspirin biodegradation using a microbial electrochemical system supplied by an alternating current.

Chemosphere 2019 Oct 23;232:35-44. Epub 2019 May 23.

Department of Environmental Health Engineering, School of Public Health, Iran University of Medical Sciences, Tehran, Iran.

The main aim of this study is to investigate the biodegradation of highly concentrated aspirin as an emerging pollutant from aqueous solution using an alternating current microbial electrochemical system. A single-chamber Plexiglas cylindrical reactor equipped with stainless steel mesh electrodes (18 cm height × 16 cm diameter) was applied as the bioreactor in batch mode with an effective volume of 5 L, height of 20 cm, and the diameter about 20 cm by AMPL = 2 V, OFST = 0.1 V, waveform = sinusoidal, frequency = 10 Hz, and pH = 7. The process parameters including initial concentration (100-400 mg L), chemical oxygen demand (COD), activity of enzymes, biokinetic and pathway studies at very low voltage and very low frequency alternating current were investigated. The specific biodegradation rate of aspirin was calculated based on Michaelis-Menten model. The complete aspirin removal efficiency and the maximum enzymatic activity were achieved at 250 mg L aspirin, voltage of 2 V and applied current = 3 mA during 6 h. The bioassay of aspirin concentrations in biofilm of the system using flow cytometry analysis resulted in the live and necrotic cells shares of 96.2%, and 0.44%, respectively. Moreover, the LC and GC-MS analysis showed low molecular weight acids such as oxalic and acetic acid at 6 h time under the optimal conditions using very low applied voltage and frequency. Obtaining low reaction time for degradation, high potential in biodegradation, oxidation and mineralization ability were the novelty of treatment system with high concentration aspirin in the study.
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http://dx.doi.org/10.1016/j.chemosphere.2019.05.186DOI Listing
October 2019

Effect of alternating electrical current on denitrifying bacteria in a microbial electrochemical system: biofilm viability and ATP assessment.

Environ Sci Pollut Res Int 2018 Nov 30;25(33):33591-33598. Epub 2018 Sep 30.

Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.

The present study considers the impact of the alternating electric current on the viability and biological activity of denitrifying bacteria in a microbial electrochemical system (MES). The bio-stimulation using low-frequency low-voltage alternating current (AC) was studied in terms of the adenosine triphosphate (ATP) level of bacteria, viability, morphological characteristics, cell size, and complexity. Apoptosis assays by flow cytometry revealed that 81-95% of the cells were non-apoptotic, and cell membrane damage occurred < 18%. The applied AC could affect the bacterial metabolic activity and ATP content in the denitrifying bacteria depending on characteristics of the alternating electric current. Scanning electron microscopy (SEM) analysis of cell morphology illustrated low cell deformations under AC stimulation. The obtained results revealed that the applied alternating electrical current could increase the metabolic activity of denitrifying bacteria, leading to a better denitrification. Graphical abstract ᅟ.
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http://dx.doi.org/10.1007/s11356-018-3170-0DOI Listing
November 2018

Nitrate removal from pharmaceutical wastewater using microbial electrochemical system supplied through low frequency-low voltage alternating electric current.

Bioelectrochemistry 2018 Apr 21;120:49-56. Epub 2017 Nov 21.

Department of Environmental Health, School of Public Health, Iran University of Medical Sciences, Tehran, Iran.

In this study, a microbial electrochemical system (MES) was designed to evaluate the effects of a low frequency-low voltage alternating electrical current on denitrification efficacy in the presence of ibuprofen as a low biodegradable organic carbon source. Cylindrical carbon cloth and stainless steel mesh electrodes containing a consortium of heterotrophic and autotrophic bacteria were mounted in the wall of the designed laboratory-scale bioreactor. The effects of inlet nitrate concentration (50-800mgL), retention time (2.5-24h), waveform magnitude (0.1-9.6V), adjustable direct current voltage added to offset voltage (0.1-4.9V), alternating current frequency (10-60Hz), and waveforms (sinusoidal, square, and ramp) were studied in this work. The results showed that the proposed system removes 800mgL nitrate up to 95% during 6.5h. Optimum conditions were obtained in the 8V using a frequency of 10Hz of a sinusoidal waveform. The morphology studies confirmed bacterial morphology change when applying the alternating current. Dehydrogenase activity of biofilms formed on surface of stainless steel electrodes increased to 15.24μgTFmgcmd. The maximum bacterial activity was obtained at a voltage of 8V. The experimental results revealed that the MES using a low frequency-low voltage alternating electrical current is a promising technique for nitrate removal from pharmaceutical wastewaters in the presence of low biodegradability of carbon sources such as ibuprofen.
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http://dx.doi.org/10.1016/j.bioelechem.2017.11.008DOI Listing
April 2018

Conductive microbial cellulose as a novel biocathode for Cr (VI) bioreduction.

Carbohydr Polym 2017 Apr 16;162:56-61. Epub 2017 Jan 16.

Faculty of Engineering, Materials Engineering Department, Tarbiat Modares University, Tehran, Iran.

In the present study, microbial cellulose (MC) as a carbohydrate polymer was made conductive by oxidative polymerization with aniline. Sulfate-reducing bacteria (SRB) were immobilized on the surface of the conductive biopolymer, and this was used as a biocathode in a bioreduction process to reduce Cr (VI) as a model of heavy metals. The results of Fourier transform infrared analysis confirmed that the polyaniline was distributed on the cellulose surface. The maximum tensile stress of the conductive biopolymer was obtained 23MPa using calculating Young's modulus. A current density of 60mA/m was determined as optimal, and an increase in pH from 5 to 7 significantly reduced the required time for reduction of Cr (VI). The system reached >99% removal of Cr (VI) within 1.5h at pH 7. Kinetic experiment studies showed a high constant rate (mean K 0.78, R 0.95). The results showed that the conductive MC can be used as an appropriate bioelectrode to reduce Cr (VI) in bioelectrochemical processes. It is expected that experimental results could be used as a reference for the utilization of MC in bioelectrochemical systems.
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http://dx.doi.org/10.1016/j.carbpol.2017.01.046DOI Listing
April 2017

Electrocatalytic oxidation of phenol from wastewater using Ti/SnO2-Sb2O4 electrode: chemical reaction pathway study.

Environ Sci Pollut Res Int 2016 Oct 13;23(19):19735-43. Epub 2016 Jul 13.

Faculty of Engineering, Materials Engineering Department, Tarbiat Modares University, Tehran, Iran.

In this study, a titanium plate was impregnated with SnO2 and Sb (Ti/SnO2-Sb2O4) for the electrocatalytic removal of phenol from wastewater, and the chemical degradation pathway was presented. The effects of various parameters such as pH, current density, supporting electrolyte, and initial phenol concentration were studied. At optimum conditions, it was found that phenol was quickly oxidized into benzoquinone because of the formation of various strong radicals during electrolysis by the Ti/SnO2-Sb2O4 anode from 100 to <1 mg/L over 1 h. The results of GC/MS analysis showed the presence of some esters of organic acid such as oxalic acid and formic acid. HPLC analysis showed only trace amounts of benzoquinone remaining in the solution. The efficiency of TOC removal at the Ti/SnO2-Sb2O4 anode surface showed a degradation rate of 49 % over 2 h. Results showed that the molecular oxygen potential at the electrode was 1.7 V. The phenol removal mechanism at the surface of the Ti/SnO2-Sb2O4 anode was influenced by the pH. Under acidic conditions, the mechanism of electron transfer occurred directly, whereas under alkaline conditions, the mechanism can be indirect. This research shows that the proposed electrolyte can significantly influence the efficiency of phenol removal. It can be concluded that the treatment using an appropriate Ti/SnO2-Sb2O4 electrode surface can result in the rapid oxidation of organic pollutants.
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http://dx.doi.org/10.1007/s11356-016-7110-6DOI Listing
October 2016

Kinetic modeling and determination role of sono/photo nanocatalyst-generated radical species on degradation of hydroquinone in aqueous solution.

Environ Sci Pollut Res Int 2016 Jun 14;23(12):12185-98. Epub 2016 Mar 14.

Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.

Experimental findings of sonophotocatalytic process were used in degradation of hydroquinone to assess kinetic modeling and determine the effect of various active radical species. First, the effects of three photocatalytic, sonocatalytic, and sonophotocatalytic processes were studied for hydroquinone removal to determine kinetic constants and calculate the activation energy of reactions, and then the selected process was evaluated to determine active radical species. The reactor was composed of two parts, one included ultrasonic probe (sonocatalytic part) with powers 22, 80, and 176 W and the second part was the location of UV lamp (photocatalytic part) with tubular flow and power 15 W. After three systems were examined and the efficient system was selected, the role of different active species such as hydroxyl radical (OH(·)), superoxide radical (O2 (·-)), hole (h(+)), electrons (e (-)), and single oxygen molecule ((1)O2) and contribution of each of them were determined in hydroquinone degradation. According to tests, the results of this study showed that sonophotocatalytic integrated method as selected system among three systems studied followed the first-order equation for hydroquinone degradation and active hydroxyl species with 45 % and electron and hole with 15 and 10 %, respectively, had the highest and lowest contributions to conversion of hydroquinone. The findings showed that dissolved oxygen increases the capability of active radical formation so that 28.2 % of hydroquinone removal was increased under aeration compared to without aeration. Also, removal efficiency decreased 62 % with N2 injection due to the withdrawal of oxygen from the sample. By adding 25 Mm of sodium azide (NaN3) to stock solution, 46.5 % reduction was developed because single oxygen ((1)O2) played the role of an active species. The advantages of integrated sonocatalytic and photocatalytic method are the generation of active radical species with more variety and ultimately the formation of higher amounts of powerful hydroxyl radical that increases degradation rates of refractory compounds and low-risk internal and final products. It has an appropriate performance in the degradation of refractory compounds by optimizing effective operational factors.
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http://dx.doi.org/10.1007/s11356-016-6408-8DOI Listing
June 2016

Effects of ethanol on the electrochemical removal of Bacillus subtilis spores from water.

J Environ Health Sci Eng 2015 18;13:78. Epub 2015 Nov 18.

Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.

This study aimed to characterize the effects of ethanol on the monopolar electrochemical process to remove Bacillus subtilis spores from drinking water. In particular, spores' destruction was tested by applying 20-100 mA current for 15-60 min to B. subtilis spores (10(2)-10(4) CFU/mL density), with stainless steel electrodes. The experimental results showed electrochemical removal of spores in the presence of 0.4 M ethanol at 15, 45, and 60 min and 5 mA/cm(2) current density. However, the use of ethanol or the electrochemical process alone did not eliminate B. subtilis spores at these time points. Overall, this study suggests that adding ethanol to the electrochemical process successfully removes B. subtilis spores from drinking water.
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http://dx.doi.org/10.1186/s40201-015-0229-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4652357PMC
November 2015

Biodegradation of Phenol in Synthetic Wastewater Using a Fixed Bed Reactor With up Flow Sludge Blanket Filtration (FUSBF).

Glob J Health Sci 2015 Mar 26;7(7 Spec No):120-30. Epub 2015 Mar 26.

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In the present study, the removal of phenol from synthetic wastewater was evaluated in a fixed bed reactor with up flow sludge blanket filtration (FUSBF) in comparison with a typical USBF system. At hydraulic retention time (HRT) of 24 hours and solid retention time (SRT) of 20 day, the effect of initial concentration of phenol (260-1020 mg/L) on phenol and chemical oxygen demand (COD) removal efficiency (%) was investigated in both systems. The effect of the presence of fixed bed was determined throughout the operational period. The results showed that the FUSBF system had a better ability than the typical USBF system in terms of phenol and COD removal. The average phenol and COD removal at phenol concentration of 312 mg/L was 97.52% and 92.82% for the FUSBF system and 92.80% and 82.18% for the typical USBF system, respectively. At HRT of 24 h and organic loading rate (OLR) of 30 g/m(-3).h(-1), the amount of phenol removal was 82.1%. At OLR of 30 g/m(-3).h(-1), role of fixed bed in phenol and COD removal was 25.01% and 29.3%, respectively, overall, the FUSBF system has a higher efficiency and ability than that of typical USBF and can be used for the purification of industrial wastewater containing refractory organic compounds such as phenol.
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http://dx.doi.org/10.5539/gjhs.v7n7p120DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4803987PMC
March 2015

Bioelectrochemical denitrification using carbon felt/multiwall carbon nanotube.

Environ Technol 2015 Mar-Apr;36(5-8):1057-62. Epub 2014 Nov 17.

a Department of Environmental Health, Faculty of Medical Sciences , Tarbiat Modares University , Tehran , Iran.

The aim of this work was to enhance the efficiency of a bioelectrochemical denitrification process using a biocathode of carbon felt (CF)/multiwall carbon nanotube (MWCNT) composite. The efficiency of the bioelectrochemical denitrification was assessed as the function of various operational parameters, such as ORP, pH, current density, retention time and nitrate concentrations. Scanning electron microscope (SEM) images of the biocathode surfaces revealed a homogeneous distribution of the MWCNT on the CF matrix. Optimum ORP, pH, current density and retention time were -100 mV, 7.0, 15 mA/cm2 and 6 h, respectively. The highest nitrate removal efficiency at the optimum condition was 92.7% for CF/MWCNT. The reduction time for achieving the nitrate standard using CF/MWCNT was 4 h. It is proposed that the prepared nanocomposite will have the best biocathode properties in the bioelectrochemistry denitrification experiments.
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http://dx.doi.org/10.1080/09593330.2014.974680DOI Listing
October 2015

Pyrene removal from contaminated soils by modified Fenton oxidation using iron nano particles.

J Environ Health Sci Eng 2013 Jul 16;11(1):17. Epub 2013 Jul 16.

Department of Environmental Health Engineering, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran.

Background: The problems related to conventional Fenton oxidation, including low pH required and production of considerable amounts of sludge have led researchers to investigate chelating agents which might improve the operating range of pH and the use of nano iron particle to reduce the excess sludge. The pyrene removal from contaminated soils by modified Fenton oxidation at neutral pH was defined as the main objective of the current study.

Methods: Varying concentrations of H2O2 (0-500 mM) and iron nano oxide (0-60 mM), reaction times of 0.5-24 hours and variety of chelating agents including sodium pyrophosphate, sodium citrate, ethylene diamine tetraacetic, fulvic and humic acid were all investigated at pyrene concentration levels of 100 - 500 mg/kg.

Results: By applying the following conditions (H2O2 concentration of 300 mM, iron nano oxide of 30 mM, sodium pyrophosphate as chelating agent, pH 3 and reaction time of 6 hours) the pyrene removal efficiency at an initial concentration of 100 mg/kg was found to be 99%. As a result, the pyrene concentration was reduced from 100 to 93 mg/kg once the above optimum conditions are met.

Conclusions: In this research, the modified Fenton oxidation using iron nano oxide at optimum conditions is introduced as an efficient alternative method in lab scale for chemical remediation or pre-treatment of soils contaminated by pyrene at neutral pH.
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http://dx.doi.org/10.1186/2052-336X-11-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4176307PMC
July 2013

Optimization of a novel setup for an on-line study of elemental mercury adsorption by cold-vapor atomic absorption spectrometry.

J Res Health Sci 2013 May 29;13(1):37-42. Epub 2013 May 29.

Department of Occupational Health Engineering, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.

Background: The objective of this work was developing a simple and stable time-based on-line setup for assessing the potential of mercury (Hg) vapor adsorption of the commercial sorbents used in air sampling and control operation followed by cold vapor atomic absorption spectrometry (CVAAS).

Methods: A special designed separation chamber was used where reduction of the injected Hg (II) solution took place. Purge gas passes through this chamber resulting to a prompt release of mercury vapor, purging into the adsorbent that regulated at the desired adsorption temperature. After sorbent saturation, in order to study the adsorption parameters of sorbents (activated carbon and bone char) such as breakthrough time (BTT), and adsorptive capacity, mercury gas stream was passed through the sorbents, directly transport to the CVAAS.

Results: Preliminary experiments concerning the reductant solution showed that SnCl2 offers higher stability than NaBH4. Around the loading range 0.125-2.5 ml min⁻¹ of 100 µg l⁻¹ Hg(II) solution, a linear calibration curve with the equation peak area=0.134; loading flow=-0.017 and a correlation coefficient r=0.996 was obtained, and the detection limit was improved up to c(L)=1 µg l⁻¹. The relative standard deviation of five measurements of lowest flow loading of Hg (II) was RSD=2.8%. The significant differences were observed in the breakthrough time and mercury adsorptive capacity between activated carbon and bone char (P=0.010).

Conclusion: This novel setup is suitable for an on-line study of elemental mercury adsorption, determination of breakthrough time and adsorption capacity, and because of its stable performance during all experiments; it can be applied to the time based studies.
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May 2013

Protection of BALB/C mice against Brucella abortus 544 challenge by vaccination with combination of recombinant human serum albumin-l7/l12 (Brucella abortus ribosomal protein) and lipopolysaccharide.

Roum Arch Microbiol Immunol 2010 Jan-Mar;69(1):5-12

Department of Microbiology, Ilam University of Medical Sciences, Ilam, Iran.

Background: The immunogenic Brucella abortus ribosomal protein L7/L12 and Lipopolysaccharide (LPS) are promising candidate antigens for the development of subunit vaccines against brucellosis.

Objective: This study was aimed to evaluate the protection of combination of recombinant HSA-L7/L12 fusion protein with LPS in Balb/c mouse.

Materials And Methods: The recombinant HSA-L7/L12 fusion protein in Saccharomyces cerevisiae was expressed and purified by affinity chromatography column. LPS was extracted by n-butanol, purified by ultracentrifugation. BALB/c mouses were immunized in 9 groups with PBS, HSA, tHSA-L7/L12, L7/L12, LPS, LPS+ HSA, LPS+ tHSA-L7/L12, LPS+ L7/L12, B. abortus S19. ELISA, LTT tests and challenging two weeks after last injection were carried out. Bacterial count of spleen of immunized BALB/c mouse was done four weeks after challenging with virulent strain B. abortus 544.

Results: In ELISA test the specific antibodies of tHSA-L7/L12 exhibited a dominance of immunoglobulin IgG1 over IgG2a. LPS-HSA and tHSA-L7/L12 + LPS produced a significantly higher antibody titer than LPS alone and L7/L12+LPS (P < 0.05). The predominant IgG subtype for LPS and L7/L12+LPS were IgG3. However, tHSA-L7/L12+ LPS and LPS+ HAS elicited predominantly IgG1 and IgG3 subtypes. In addition, the tHSA-L7/L12 fusion protein and L7/L12 elicited a strong T-cell proliferative response upon restimulation in vitro with recombinant tHSA-L7/L12 and L7/L12, suggesting the induction of a cellular immunity response in vivo. However, there was no significant difference proliferative response in L7/L12 and tHSA-L7/L12 fusion protein (P > 0.05). The combination of tHSA-L7/L12 fusion protein with LPS and B. abortus S19 induce higher level of protection against challenge with the virulent strain B. abortus 544 in BALB/c mice than other groups (P = 0.005).

Conclusions: The combination of tHSA-L7/L12 fusion protein with LPS had higher protective ability than LPS and fusion protein distinctly.
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December 2010

Expression of human serum albumin--L7/L12 (Brucella abortus ribosomal protein) fusion protein in Saccharomyces cerevisiae.

Pol J Microbiol 2009 ;58(2):99-104

Department of Microbiology, School of Medicine, Ilam University of Medical Sciences, Ilam, Iran.

Brucella abortus is a facultative intracellular gram-negative bacterial pathogen that causes abortion in pregnant cattle and undulant fever in humans. The immunogenic B. abortus ribosomal protein L7/L12 is a promising candidate antigen for the development of subunit vaccines against brucellosis. It has already been expressed in several bacteria and has been used as DNA vaccine. In order to construct yeast expressing vector for the tHSA-L7/L12 fusion protein, the l7/l12 ribosomal gene was amplified by PCR. The expression plasmid pYtHSA-L7/L12 was constructed by inserting the L7/L12 gene into the pYHSA5 shuttle vector (containing inulinase signal sequence, HSA gene and Gal10 promoter). The recombinant vector was transformed into S. cerevisiae and was then induced by galactose. The secreted recombinant fusion protein was detected in supernatant by SDS-PAGE and confirmed by western blot analysis using anti-HSA and anti-L7/L12 antibodies. Fusion protein was purified by affinity chromatography and its amount was approximately 500 microg/liter.
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November 2009

Immunogencity of HSA-L7/L12 (Brucella abortus ribosomal protein) in an animal model.

Iran J Immunol 2009 Mar;6(1):12-21

Department of Microbiology, Ilam University of Medical Sciences, Ilam, Iran.

Background: The immunogenic Brucella abortus ribosomal protein L7/L12 is a promising candidate antigen for the development of subunit vaccines against brucellosis.

Objective: This study was aimed to evaluate the protection of recombinant Human Serum Albumin (HAS)-L7/L12 fusion protein in Balb/c mice.

Methods: The amplified L7/L12 gene was cloned in pYHSA5 vector, pYHSA5-L7/L12 construct was transformed in Saccharomyces cerevisiae and the expressed protein from supernatant was purified by affinity chromatography. Balb/c mice were immunized in five groups by tHSA-L7/L12 fusion protein (group 1), Brucella abortus S19 (group 2), HSA (group 3), recombinant L7/L12 (group 4), PBS (group 5). ELISA to detect antibody production, LTT test to assess antigen specific lymphocyte response were conducted prior to virulent B. abortus strain 544 challenge two weeks after the last injection. Bacterial counts from spleens of immunized mice were done four weeks after challenge.

Results: In ELISA tests, the specific antibodies exhibited a dominance of immunoglobulin IgG1 over IgG2a. In addition, the tHSA-L7/L12 fusion protein and L7/L12 elicited a strong T-cell proliferative response upon restimulation in vitro with recombinant tHSA-L7/L12 and L7/L12, suggesting the induction of a cellular immunity response in vivo. However, there was no significant difference in proliferative response of L7/L12 and tHSA-L7/L12 fusion protein (p>0.05). The L7/L12 and tHSA-L7/L12 fusion protein vaccines could also induce significant protection against challenge with the virulent strain B. abortus 544 in Balb/c mice (p< or =0.05).

Conclusion: The tHSA-L7/L12 fusion protein, similar to L7/L12 has the ability to induce antigen specific lymphocyte proliferation, stimulate humoral immunity and engender protection.
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http://dx.doi.org/IJIv6i1A2DOI Listing
March 2009

Expression of Escherichia coli heat-labile enterotoxin B subunit (LTB) in Saccharomyces cerevisiae.

J Microbiol 2005 Aug;43(4):354-60

Faculty of Medical Sciences, Tarbiat Modarres University, P.O.Box 14115-111, Tehran, Iran.

Heat-labile enterotoxin B subunit (LTB) of enterotoxigenic Escherichia coli (ETEC) is both a strong mucosal adjuvant and immunogen. It is a subunit vaccine candidate to be used against ETEC-induced diarrhea. It has already been expressed in several bacterial and plant systems. In order to construct yeast expressing vector for the LTB protein, the eltB gene encoding LTB was amplified from a human origin enterotoxigenic E. coli DNA by PCR. The expression plasmid pLTB83 was constructed by inserting the eltB gene into the pYES2 shuttle vector immediately downstream of the GAL1 promoter. The recombinant vector was transformed into S. cerevisiae and was then induced by galactose. The LTB protein was detected in the total soluble protein of the yeast by SDS-PAGE analysis. Quantitative ELISA showed that the maximum amount of LTB protein expressed in the yeast was approximately 1.9% of the total soluble protein. Immunoblotting analysis showed the yeast-derived LTB protein was antigenically indistinguishable from bacterial LTB protein. Since the whole-recombinant yeast has been introduced as a new vaccine formulation the expression of LTB in S. cerevisiae can offer an inexpensive yet effective strategy to protect against ETEC, especially in developing countries where it is needed most.
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August 2005

Characteristics of Saccharomyces cerevisiae gal1 Delta and gal1 Delta hxk2 Delta mutants expressing recombinant proteins from the GAL promoter.

Biotechnol Bioeng 2005 Mar;89(6):619-29

Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-333, Korea.

Galactose can be used not only as an inducer of the GAL promoters, but also as a carbon source by Saccharomyces cerevisiae, which makes recombinant fermentation processes that use GAL promoters complicated and expensive. To overcome this problem during the cultivation of the recombinant strain expressing human serum albumin (HSA) from the GAL10 promoter, a gal1 Delta mutant strain was constructed and its induction kinetics investigated. As expected, the gal1 Delta strain did not use galactose, and showed high levels of HSA expression, even at extremely low galactose concentrations (0.05-0.1 g/L). However, the gal1 Delta strain produced much more ethanol, in a complex medium containing glucose, than the GAL1 strain. To improve the physiological properties of the gal1 Delta mutant strain as a host for heterologous protein production, a null mutation of either MIG1 or HXK2 was introduced into the gal1 Delta mutant strain, generating gal1 Delta mig1 Delta and gal1 Delta hxk2 Delta double strains. The gal1 Delta hxk2 Delta strain showed a decreased rate of ethanol synthesis, with an accelerated rate of ethanol consumption, compared to the gal1 Delta strain, whereas the gal1 Delta mig1 Delta strain showed similar patterns to the gal1 Delta strain. Furthermore, the gal1 Delta hxk2 Delta strain secreted much more recombinant proteins (HSA and HSA fusion proteins) than the other strains. The results suggest that the gal1 Delta hxk2 Delta strain would be useful for the large-scale production of heterologous proteins from the GAL10 promoter in S. cerevisiae.
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http://dx.doi.org/10.1002/bit.20240DOI Listing
March 2005