Pub Date : 2018-10-01DOI: 10.22104/AET.2019.3371.1167
M. Rafati, M. Pazouki, H. Ghadamian, A. Hosseinnia, A. Jalilzadeh
Despite the fact that there are wastewater treatment plants (WWTPs) currently operational across Iran and great advances have been made in this area, there are still problems in the design, construction, and operation of WWTPs with large nonlinear systems, varying flow rates, and pollution charges. The objective of this study was to investigate the effect of operating parameters including the return activated sludge (RAS) ratio, internal recycle (IR) ratio and dissolved oxygen (DO) concentration in an activated sludge system for the Modules 5&6 of the Southern Tehran WWTP. This study designed and simulated a plant based on the activated sludge model No.1 (ASM1) to determine the factors affecting wastewater treatment systems; then, the kinetic parameters were measured. The kinetic parameters such as the yield coefficient (Y), decay coefficient (Kd), maximum specific growth rate (K), and saturation constant (Ks) were in the range of 0.303-0.331g/g, 0.030-0.033d-1, 1.65-1.93d-1 and 37.6-44.92mg/l, respectively. The RAS ratios, IR ratios, and DO concentration varied from 0.2 to 2, 1 to 3.5, and 0.27 to 3.54 mg/l, respectively. The amount of RAS had the greatest impact on the effluent. The amounts of IR and DO concentration had no significant effect on the concentration of the five-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), and total suspended solids (TSS) in the effluent. After the RAS, the amount of IR had the most direct effect on reducing the effluent total nitrogen (TN) concentration. As a result, the overall removal efficiency increased up to 75% when the IR rate was 200% of the influent flow rate, the RAS rate was 90% of the influent flow rate, and the DO concentration in the first aeration unit was 2 mg/l considering the aeration cost. Therefore, proper operating parameters can provide the best quality of effluent that meets environmental standards.
{"title":"Effect of operating parameters on the performance of wastewater treatment plant (Case study: The south of Tehran wastewater treatment)","authors":"M. Rafati, M. Pazouki, H. Ghadamian, A. Hosseinnia, A. Jalilzadeh","doi":"10.22104/AET.2019.3371.1167","DOIUrl":"https://doi.org/10.22104/AET.2019.3371.1167","url":null,"abstract":"Despite the fact that there are wastewater treatment plants (WWTPs) currently operational across Iran and great advances have been made in this area, there are still problems in the design, construction, and operation of WWTPs with large nonlinear systems, varying flow rates, and pollution charges. The objective of this study was to investigate the effect of operating parameters including the return activated sludge (RAS) ratio, internal recycle (IR) ratio and dissolved oxygen (DO) concentration in an activated sludge system for the Modules 5&6 of the Southern Tehran WWTP. This study designed and simulated a plant based on the activated sludge model No.1 (ASM1) to determine the factors affecting wastewater treatment systems; then, the kinetic parameters were measured. The kinetic parameters such as the yield coefficient (Y), decay coefficient (Kd), maximum specific growth rate (K), and saturation constant (Ks) were in the range of 0.303-0.331g/g, 0.030-0.033d-1, 1.65-1.93d-1 and 37.6-44.92mg/l, respectively. The RAS ratios, IR ratios, and DO concentration varied from 0.2 to 2, 1 to 3.5, and 0.27 to 3.54 mg/l, respectively. The amount of RAS had the greatest impact on the effluent. The amounts of IR and DO concentration had no significant effect on the concentration of the five-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), and total suspended solids (TSS) in the effluent. After the RAS, the amount of IR had the most direct effect on reducing the effluent total nitrogen (TN) concentration. As a result, the overall removal efficiency increased up to 75% when the IR rate was 200% of the influent flow rate, the RAS rate was 90% of the influent flow rate, and the DO concentration in the first aeration unit was 2 mg/l considering the aeration cost. Therefore, proper operating parameters can provide the best quality of effluent that meets environmental standards.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"26 1","pages":"211-221"},"PeriodicalIF":0.0,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87306683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-01DOI: 10.22104/AET.2019.3258.1159
N. Oroujzadeh
Magnetic chitosan nanocomposites are one of the more recent advanced groups of adsorbents used to remove contaminants from waste water. In this research, N- Nicotinyl-N', N"-bis (Hexamethylenyl) phosphoric triamide (HE) was used as an additive to form a new nanocomposite with the structure of chitosan / 5% Fe3O4 Nps/10% HE resulting in the highly efficient removal of Cd(II) ions from an aqueous solution. Several techniques were applied to characterize the new-fabricated nanocomposite: X-ray Powder Diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDX), Field Emission Scanning Electron Microscopy (FE-SEM), Fourier transform infrared (FTIR) and vibrating sample magnetometer (VSM). Atomic Absorption Spectroscopy (AAS) was used to measure the removal percentage of Cd(II) ions from the contaminated water samples. Results showed that 15 mg of the nanocomposite could remove Cd(II) ions with a rate of 99.9% from 20 mL of its 100 ppm aqueous solution in pH=9 with contact time of 1h. Furthermore, the same amount of the nanocomposite was applied to remove Cd(II) ions from 20 mL of a real wastewater sample with a pH=9 and the same contact time. The resulting removal rate of Cd(II) ions was 99.5%.
磁性壳聚糖纳米复合材料是近年来用于去除废水中污染物的先进吸附剂之一。本研究以N- Nicotinyl-N′，N′-双(六亚甲基)磷酸三酰胺(HE)为添加剂，形成壳聚糖/ 5% Fe3O4 Nps/10% HE结构的新型纳米复合材料，可高效去除水溶液中的Cd(II)离子。采用x射线粉末衍射(XRD)、能量色散x射线能谱(EDX)、场发射扫描电镜(FE-SEM)、傅里叶变换红外(FTIR)和振动样品磁强计(VSM)等技术对新制备的纳米复合材料进行了表征。原子吸收光谱法(AAS)测定了污染水样中Cd(II)离子的去除率。结果表明，在pH=9的100ppm水溶液中，15 mg纳米复合材料对Cd(II)离子的去除率为99.9%，接触时间为1h。此外，应用相同量的纳米复合材料从20 mL pH=9的实际废水样品中去除Cd(II)离子，接触时间相同。对Cd(II)离子的去除率为99.5%。
{"title":"Removal of Cd(II) ions from contaminated water by a new modified magnetic chitosan nano composite","authors":"N. Oroujzadeh","doi":"10.22104/AET.2019.3258.1159","DOIUrl":"https://doi.org/10.22104/AET.2019.3258.1159","url":null,"abstract":"Magnetic chitosan nanocomposites are one of the more recent advanced groups of adsorbents used to remove contaminants from waste water. In this research, N- Nicotinyl-N', N\"-bis (Hexamethylenyl) phosphoric triamide (HE) was used as an additive to form a new nanocomposite with the structure of chitosan / 5% Fe3O4 Nps/10% HE resulting in the highly efficient removal of Cd(II) ions from an aqueous solution. Several techniques were applied to characterize the new-fabricated nanocomposite: X-ray Powder Diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDX), Field Emission Scanning Electron Microscopy (FE-SEM), Fourier transform infrared (FTIR) and vibrating sample magnetometer (VSM). Atomic Absorption Spectroscopy (AAS) was used to measure the removal percentage of Cd(II) ions from the contaminated water samples. Results showed that 15 mg of the nanocomposite could remove Cd(II) ions with a rate of 99.9% from 20 mL of its 100 ppm aqueous solution in pH=9 with contact time of 1h. Furthermore, the same amount of the nanocomposite was applied to remove Cd(II) ions from 20 mL of a real wastewater sample with a pH=9 and the same contact time. The resulting removal rate of Cd(II) ions was 99.5%.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"59 1","pages":"187-195"},"PeriodicalIF":0.0,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82886287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.22104/AET.2019.3010.1147
Milad Hallajiqomi, Mohsen Mehdipour Ghazi, F. Varaminian
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.
{"title":"Degradation of Diazinon from aqueous solution using Silver-modified Clinoptilolite Zeolite in photocatalytic process","authors":"Milad Hallajiqomi, Mohsen Mehdipour Ghazi, F. Varaminian","doi":"10.22104/AET.2019.3010.1147","DOIUrl":"https://doi.org/10.22104/AET.2019.3010.1147","url":null,"abstract":"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.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"99 1","pages":"175-182"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81443374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.22104/AET.2019.2619.1132
Hakimeh Sharififard
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.
{"title":"Statistical physics modeling of equilibrium adsorption of cadmium ions onto activated carbon, chitosan and chitosan/activated carbon composite","authors":"Hakimeh Sharififard","doi":"10.22104/AET.2019.2619.1132","DOIUrl":"https://doi.org/10.22104/AET.2019.2619.1132","url":null,"abstract":"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.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"163 1","pages":"149-154"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72779566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.22104/AET.2019.3153.1153
Mohsen Kojuri, F. Ardestani
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.
{"title":"Isolation, identification and evaluation of oil hydrocarbon decomposing bacteria from contaminated areas of oil fields","authors":"Mohsen Kojuri, F. Ardestani","doi":"10.22104/AET.2019.3153.1153","DOIUrl":"https://doi.org/10.22104/AET.2019.3153.1153","url":null,"abstract":"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.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"10 1","pages":"139-147"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89258870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.22104/AET.2019.3372.1165
E. Ziarifar, R. Rahimi, M. Zivdar
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.
{"title":"Using disulfide oil as coke inhibitor to reduce environmental hazards in olefin heaters","authors":"E. Ziarifar, R. Rahimi, M. Zivdar","doi":"10.22104/AET.2019.3372.1165","DOIUrl":"https://doi.org/10.22104/AET.2019.3372.1165","url":null,"abstract":"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.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"16 1","pages":"183-186"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80519656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.22104/AET.2019.3216.1156
abdollah mohammadpoor, M. Mirzaei, A. Azimi, mostafa tabatabaee ghomshe
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.
{"title":"The simultaneous effect of graphene oxide and sodium dodecyl sulphate nanoparticles on the kinetics of CO2 absorption in amine","authors":"abdollah mohammadpoor, M. Mirzaei, A. Azimi, mostafa tabatabaee ghomshe","doi":"10.22104/AET.2019.3216.1156","DOIUrl":"https://doi.org/10.22104/AET.2019.3216.1156","url":null,"abstract":"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.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"27 1","pages":"163-174"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81926835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.22104/AET.2019.2155.1107
M. Pirooz, N. Akbari, M. Kamali, D. Biria
This study investigated different methods of controlling the fat, oil and grease (FOG) in sewer systems. A comprehensive control program was developed for 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 included guidelines for food service establishments, which are the major sources of (FOG). Food service establishments must implement better management practices to reduce (FOG) from entering the facility drain and install grease removal devices. As a part of preventive cleaning, the performance 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 nonylphenol ethoxylate 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 a contact time of 36 h, shaking rate of 30 rpm and surfactant concentration of 12.5%. The second part of the program consisted of removing dead zones and increasing wastewater velocity in the sewer lines to enhance the hydraulic condition of the sewer system and decrease fat deposition. Finally, a detailed and well-defined control program could solve FOG problems in sewer systems.
本研究探讨了污水处理系统中油脂(FOG)的不同控制方法。为马什哈德市(伊朗)制定了一项全面的控制方案，以维护其下水道系统并防止堵塞。控制程序包括三个部分:1)脂肪，油和油脂来源控制，2)下水道系统改造，3)预防性维护。该方案包括食品服务机构的指导方针，这是(FOG)的主要来源。餐饮服务机构必须实施更好的管理措施，减少污水进入设施排水渠，并安装除油装置。作为预防性清洗的一部分，对几种表面活性剂作为清洗剂的性能进行了评价。两种工业表面活性剂，一种含有单乙基胺和磺化十二烷基醇，一种含有壬基酚聚氧乙酸酯和氢氧化钾，以50:50的比例(10 v. %的水)混合，效果最好，去除80%的脂肪。采用响应面法确定了表面活性剂的最佳工艺条件。最佳工艺条件为接触时间36 h，摇摇速度30 rpm，表面活性剂浓度12.5%。该方案的第二部分包括消除死区和增加污水管道中的污水流速，以改善下水道系统的水力条件，减少脂肪沉积。最后，一个详细的、定义良好的控制程序可以解决下水道系统中的FOG问题。
{"title":"Investigation of thecontrol of the fat, oil and grease in sewer lines and their removal by surfactant treatment","authors":"M. Pirooz, N. Akbari, M. Kamali, D. Biria","doi":"10.22104/AET.2019.2155.1107","DOIUrl":"https://doi.org/10.22104/AET.2019.2155.1107","url":null,"abstract":"This study investigated different methods of controlling the fat, oil and grease (FOG) in sewer systems. A comprehensive control program was developed for 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 included guidelines for food service establishments, which are the major sources of (FOG). Food service establishments must implement better management practices to reduce (FOG) from entering the facility drain and install grease removal devices. As a part of preventive cleaning, the performance 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 nonylphenol ethoxylate 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 a contact time of 36 h, shaking rate of 30 rpm and surfactant concentration of 12.5%. The second part of the program consisted of removing dead zones and increasing wastewater velocity in the sewer lines to enhance the hydraulic condition of the sewer system and decrease fat deposition. Finally, a detailed and well-defined control program could solve FOG problems in sewer systems.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"12 1","pages":"155-161"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84005681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-04-01DOI: 10.22104/AET.2019.2561.1130
F. Taran, A. Sadraddini, A. Nazemi
Laboratory and field experiments have shown that dispersivity is one of the key parameters in contaminant transport in porous media and varies with elapsed time. This time-dependence can be shown using a time-variable dispersivity function. The advantage of this function as opposed to constant dispersivity is that it has at least two coefficients that increase the accuracy of the dispersivity prediction. In this study, longitudinal dispersivity values were obtained for the conservative NaCl solute transport in a laboratory porous medium saturated with tap water. The results showed that the longitudinal dispersivity initially increased with time (pre-asymptotic stage) and eventually reached a constant value (asymptotic stage). Four functions were used to investigate the time variations of dispersivity: linear, power, exponential and logarithmic. In general, because of the linear increase of dispersivity during a long time of transport, the linear function with R2=0.97 showed better time variations than the other three functions; the logarithmic function, having an asymptotic nature, predicted the asymptotic stage successfully (R2=0.95). The ratio of the longitudinal dispersivity to the medium length was not constant during the transport process and varied from 0.01 to 0.05 cm with elapsed time.
{"title":"Experimental and Mathematical Investigation of Time-Dependence of Contaminant Dispersivity in Soil","authors":"F. Taran, A. Sadraddini, A. Nazemi","doi":"10.22104/AET.2019.2561.1130","DOIUrl":"https://doi.org/10.22104/AET.2019.2561.1130","url":null,"abstract":"Laboratory and field experiments have shown that dispersivity is one of the key parameters in contaminant transport in porous media and varies with elapsed time. This time-dependence can be shown using a time-variable dispersivity function. The advantage of this function as opposed to constant dispersivity is that it has at least two coefficients that increase the accuracy of the dispersivity prediction. In this study, longitudinal dispersivity values were obtained for the conservative NaCl solute transport in a laboratory porous medium saturated with tap water. The results showed that the longitudinal dispersivity initially increased with time (pre-asymptotic stage) and eventually reached a constant value (asymptotic stage). Four functions were used to investigate the time variations of dispersivity: linear, power, exponential and logarithmic. In general, because of the linear increase of dispersivity during a long time of transport, the linear function with R2=0.97 showed better time variations than the other three functions; the logarithmic function, having an asymptotic nature, predicted the asymptotic stage successfully (R2=0.95). The ratio of the longitudinal dispersivity to the medium length was not constant during the transport process and varied from 0.01 to 0.05 cm with elapsed time.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"48 1","pages":"131-138"},"PeriodicalIF":0.0,"publicationDate":"2018-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86331053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-04-01DOI: 10.22104/AET.2018.2965.1144
S. Khosroshahi, A. Miroliaei, Y. Jafarzadeh
Polyvinyl chloride (PVC) membranes containing pristine and modified multiwall carbon nanotube (MWCNT) were prepared and characterized. MWCNT was modified in order to achieve well-dispersion within the membranes. The results of FTIR analysis revealed that MWCNT was successfully carboxylated. The FESEM images indicated that the number of pores on the surface of membranes increased at the presence of pristine and modified MWCNT and the pore size distribution curves shifted towards smaller pores. The hydrophilicity, pure water flux, tensile strength and abrasion resistance of the membranes increased with increasing the content of MWCNT and COOH-MWCNT up to 0.3 wt. % and then decreased due to the agglomeration of nanotubes. Nevertheless, at the same content of nanotubes, COOH-MWCNT had more effect than MWCNT. The performance of the membranes was studied by filtration of humic acid (HA) solution and the results showed that HA rejection reached a peak of 96.88% for 0.3 wt. % PVC/MWCNT-COOH nanocomposite membrane. Finally, it was found that the antifouling properties of the membranes increased with increasing nanotube content, especially COOH-MWCNT.
{"title":"Preparation and characterization of MWCNT-COOH/PVC ultrafiltration membranes to use in water treatment","authors":"S. Khosroshahi, A. Miroliaei, Y. Jafarzadeh","doi":"10.22104/AET.2018.2965.1144","DOIUrl":"https://doi.org/10.22104/AET.2018.2965.1144","url":null,"abstract":"Polyvinyl chloride (PVC) membranes containing pristine and modified multiwall carbon nanotube (MWCNT) were prepared and characterized. MWCNT was modified in order to achieve well-dispersion within the membranes. The results of FTIR analysis revealed that MWCNT was successfully carboxylated. The FESEM images indicated that the number of pores on the surface of membranes increased at the presence of pristine and modified MWCNT and the pore size distribution curves shifted towards smaller pores. The hydrophilicity, pure water flux, tensile strength and abrasion resistance of the membranes increased with increasing the content of MWCNT and COOH-MWCNT up to 0.3 wt. % and then decreased due to the agglomeration of nanotubes. Nevertheless, at the same content of nanotubes, COOH-MWCNT had more effect than MWCNT. The performance of the membranes was studied by filtration of humic acid (HA) solution and the results showed that HA rejection reached a peak of 96.88% for 0.3 wt. % PVC/MWCNT-COOH nanocomposite membrane. Finally, it was found that the antifouling properties of the membranes increased with increasing nanotube content, especially COOH-MWCNT.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"35 1","pages":"95-105"},"PeriodicalIF":0.0,"publicationDate":"2018-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74164389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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