Sequencing batch reactor (SBR) technology has found many applications in industrial wastewater treatment in recent years. The aim of this study was to determine the optimal time for a cycle of the sequencing batch reactor (SBR) and evaluate the performance of a SBR for petrochemical wastewater treatment in that cycle time. The reactor was operated with a suspended biomass configuration under aerobic conditions. Carbon removal and operating parameters such as pH, temperature and dissolved oxygen (DO) were monitored during the wastewater treatment. The SBR was run at different cycle times and amongst the cycle times tested, the best performance was obtained with a 7 h cycle time composed of a fill time of 15min, reaction of 6 h, settling of 30 min, and withdrawal of 15 min. The SBR with the determined cycle time was used to study the treatment of wastewater with various organic loading rates (12.88 gr COD/L.d, 18.02 gr COD/L.d and 31.39 gr COD/L.d). The SBR performance was evaluated by chemical oxygen demand (COD), total solids (TS) total suspended solids (TSS) removal efficiencies. During the shock loading tests, the maximum COD, TS and TSS removal efficiencies were 84%, 67% and 92%, respectively.
序批式反应器(SBR)技术近年来在工业废水处理中得到了广泛应用。本研究的目的是确定顺序间歇反应器(SBR)循环的最佳时间，并评估该循环时间内SBR处理石化废水的性能。反应器在好氧条件下以悬浮生物质结构运行。在废水处理过程中监测了碳去除率和pH、温度和溶解氧(DO)等操作参数。在不同的循环时间下，SBR的运行效果最佳，其循环时间为7 h，其中填充时间为15min，反应时间为6 h，沉淀时间为30 min，提取时间为15min。在确定的循环时间下，SBR对不同有机物负荷率(COD/L为12.88 g)的废水进行了处理研究。d, 18.02 gr COD/L。d和31.39 gr COD/L.d)。通过化学需氧量(COD)、总固体(TS)、总悬浮物(TSS)的去除率评价SBR的性能。在冲击载荷试验中，COD、TS和TSS的最大去除率分别为84%、67%和92%。
{"title":"Evaluation of Sequencing Batch Reactor Performance for Petrochemical Wastewater Treatment","authors":"M. Salari, S. Ataei, F. Bakhtiyari","doi":"10.22104/AET.2017.576","DOIUrl":"https://doi.org/10.22104/AET.2017.576","url":null,"abstract":"Sequencing batch reactor (SBR) technology has found many applications in industrial wastewater treatment in recent years. The aim of this study was to determine the optimal time for a cycle of the sequencing batch reactor (SBR) and evaluate the performance of a SBR for petrochemical wastewater treatment in that cycle time. The reactor was operated with a suspended biomass configuration under aerobic conditions. Carbon removal and operating parameters such as pH, temperature and dissolved oxygen (DO) were monitored during the wastewater treatment. The SBR was run at different cycle times and amongst the cycle times tested, the best performance was obtained with a 7 h cycle time composed of a fill time of 15min, reaction of 6 h, settling of 30 min, and withdrawal of 15 min. The SBR with the determined cycle time was used to study the treatment of wastewater with various organic loading rates (12.88 gr COD/L.d, 18.02 gr COD/L.d and 31.39 gr COD/L.d). The SBR performance was evaluated by chemical oxygen demand (COD), total solids (TS) total suspended solids (TSS) removal efficiencies. During the shock loading tests, the maximum COD, TS and TSS removal efficiencies were 84%, 67% and 92%, respectively.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"390 1","pages":"133-137"},"PeriodicalIF":0.0,"publicationDate":"2017-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80309727","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}
Different numerical and analytical models are presently available that provide the tools to predict pollutant and water transfer processes between the soil surface and the groundwater level. Among the existing models, the Hydrus-1D model has been used for years in the prediction of water and pollutants transfer in the unsaturated zone. The main purpose of this paper was to model the movement of the landfill leachate in the soil at the Aradkouh landfill and predict the changes in nitrogen and phosphorus concentration in the leachate at different depths. Two pilots were used in this study, one included the local soil and the other contained local soil with Vetiver grass (Chrysopogon zizanioides). After its initial purification, the resultant leachate entered the pilot and was collected after passing through the soil. Finally, the flow of the leachate movement as well as the nitrogen and phosphorus concentration changes in soil were modeled by using Hydrus-1D. The prediction model for the phosphate and nitrogen concentration changes at different depths showed that the best results were obtained in the surface charge of 0.12 m3/m2.week and by the pilot with the Vetiver grass. The results showed that the use of Vetiver grass in surface purification increased the efficiency of the purification.
{"title":"Simulation of municipal landfill leachate movement in soil by HYDRUS-1D model","authors":"M. Pazoki, R. Ghasemzade, P. Ziaee","doi":"10.22104/AET.2017.590","DOIUrl":"https://doi.org/10.22104/AET.2017.590","url":null,"abstract":"Different numerical and analytical models are presently available that provide the tools to predict pollutant and water transfer processes between the soil surface and the groundwater level. Among the existing models, the Hydrus-1D model has been used for years in the prediction of water and pollutants transfer in the unsaturated zone. The main purpose of this paper was to model the movement of the landfill leachate in the soil at the Aradkouh landfill and predict the changes in nitrogen and phosphorus concentration in the leachate at different depths. Two pilots were used in this study, one included the local soil and the other contained local soil with Vetiver grass (Chrysopogon zizanioides). After its initial purification, the resultant leachate entered the pilot and was collected after passing through the soil. Finally, the flow of the leachate movement as well as the nitrogen and phosphorus concentration changes in soil were modeled by using Hydrus-1D. The prediction model for the phosphate and nitrogen concentration changes at different depths showed that the best results were obtained in the surface charge of 0.12 m3/m2.week and by the pilot with the Vetiver grass. The results showed that the use of Vetiver grass in surface purification increased the efficiency of the purification.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"77 1","pages":"177-184"},"PeriodicalIF":0.0,"publicationDate":"2017-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90441823","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 : 2017-08-25DOI: 10.22104/AET.2017.1714.1077
F. Tangestani, M. Mallah, A. Rashidi, R. Habibzadeh
In this study, the adsorption of cesium, strontium, and rubidium radionuclides by ferritin magmolecules in a batch system was investigated under different experimental conditions. The experiments were conducted in a pilot plant that involved the contactor unit and the magnetic separator unit. The impact of the pollutant concentrations, adsorbent concentration, and pH on the efficiency of the process were investigated thoroughly. The maximum recovery of radionuclides in the studied domain were 57.05%, 85.42% and 71.82% for Cs+, Sr2+ and Rb+ ,respectively, in which the pollutant concentration was 363.63 mg/l, the adsorbent concentration was 0.011 g/l, and the pH was 7.5. The results showed that the ferritin adsorbent in the magmolecular process manifested a higher efficiency in adsorbing the bivalent ions of strontium compared to the univalent ions of cesium and rubidium. Furthermore, the results were statistically analyzed and the model and residual plots of each radionuclide were presented. The results also signified relationships between the independent variables and recovery.
{"title":"Adsorption of Cesium, Strontium, and Rubidium radionuclides in the Mag-molecular process: The influence of important factors","authors":"F. Tangestani, M. Mallah, A. Rashidi, R. Habibzadeh","doi":"10.22104/AET.2017.1714.1077","DOIUrl":"https://doi.org/10.22104/AET.2017.1714.1077","url":null,"abstract":"In this study, the adsorption of cesium, strontium, and rubidium radionuclides by ferritin magmolecules in a batch system was investigated under different experimental conditions. The experiments were conducted in a pilot plant that involved the contactor unit and the magnetic separator unit. The impact of the pollutant concentrations, adsorbent concentration, and pH on the efficiency of the process were investigated thoroughly. The maximum recovery of radionuclides in the studied domain were 57.05%, 85.42% and 71.82% for Cs+, Sr2+ and Rb+ ,respectively, in which the pollutant concentration was 363.63 mg/l, the adsorbent concentration was 0.011 g/l, and the pH was 7.5. The results showed that the ferritin adsorbent in the magmolecular process manifested a higher efficiency in adsorbing the bivalent ions of strontium compared to the univalent ions of cesium and rubidium. Furthermore, the results were statistically analyzed and the model and residual plots of each radionuclide were presented. The results also signified relationships between the independent variables and recovery.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"46 1","pages":"139-149"},"PeriodicalIF":0.0,"publicationDate":"2017-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88927453","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}
Dye-containing wastewater generated from textile industries is a major source of environmental pollution. Azo dyes, which are the largest group of coloring agents, are widely used in industries.This research investigated the photocatalytic decolorization and degradation of an azo dye Reactive Red 198 (RR198) in aqueous solution with TiO2-P25 (Degussa) as photocatalyst in slurry form using UV light. There is a significant difference in adsorption of dye on TiO2 surface with the change in the solution pH. The effect of various parameters such as catalyst loading, pH and initial concentration of the dye on decolorization and degradation have been determined. The optimum conditions of the reactor were acquired at dye concentration = 62 ppm, pH = 3.7, catalyst concentration = 2.25 g.L-1, in which dye removal efficiency was 98%. Catalyst loading (relevant coefficient = 19.25) and pH (relevant coefficient = −2.62) were resulted respectively as the most and less effective parameters on dye removal
{"title":"Investigation of affecting operational parameters in photocatalytic degradation of reactive red 198 with TiO2: optimization through response surface methodology","authors":"Farzaneh Asvadi, N. Fallah, S. Elyasi, F. Mohseni","doi":"10.22104/AET.2017.482","DOIUrl":"https://doi.org/10.22104/AET.2017.482","url":null,"abstract":"Dye-containing wastewater generated from textile industries is a major source of environmental pollution. Azo dyes, which are the largest group of coloring agents, are widely used in industries.This research investigated the photocatalytic decolorization and degradation of an azo dye Reactive Red 198 (RR198) in aqueous solution with TiO2-P25 (Degussa) as photocatalyst in slurry form using UV light. There is a significant difference in adsorption of dye on TiO2 surface with the change in the solution pH. The effect of various parameters such as catalyst loading, pH and initial concentration of the dye on decolorization and degradation have been determined. The optimum conditions of the reactor were acquired at dye concentration = 62 ppm, pH = 3.7, catalyst concentration = 2.25 g.L-1, in which dye removal efficiency was 98%. Catalyst loading (relevant coefficient = 19.25) and pH (relevant coefficient = −2.62) were resulted respectively as the most and less effective parameters on dye removal","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"62 1","pages":"169-177"},"PeriodicalIF":0.0,"publicationDate":"2017-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89427757","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}
In this study, a lab-scale membrane bioreactor (MBR) was operated for a period of more than 10 months to determine the biokinetic coefficients of the system under the hydraulic retention times (HRT) of 20, 15 and 10 hrs and sludge retention times (SRT) of 5-20 days. The results revealed that the biological removal efficiency of styrene and ethylbenzene at a solid retention time of 20 day and a hydraulic retention time of 15 hr was higher compared to a SRT of 10 day and at the same HRT. The results also showed that the yield (Y), the endogenous decay coefficient (kd), the maximum specific growth rate (μmax), and the saturation constant (Ks) for styrene and ethylbenzene as substrate were 0.60 and 0.60 mg/mg, 0.25 and 0.25 day−1, 0.188 and 0.363 h-1, and 0.146 and 2.82 mg /l, respectively. Furthermore, ethylbenzene was more appropriate as a source of carbon to activated sludge in the membrane bioreactor than the styrene which had a lower μmax than ethylbenzene.
{"title":"Biokinetic coefficients determination of a MBR for styrene and ethylbenzene as substrate base on Andrews model","authors":"S. Seyedi, H. Hazrati, J. Shayegan","doi":"10.22104/AET.2017.468","DOIUrl":"https://doi.org/10.22104/AET.2017.468","url":null,"abstract":"In this study, a lab-scale membrane bioreactor (MBR) was operated for a period of more than 10 months to determine the biokinetic coefficients of the system under the hydraulic retention times (HRT) of 20, 15 and 10 hrs and sludge retention times (SRT) of 5-20 days. The results revealed that the biological removal efficiency of styrene and ethylbenzene at a solid retention time of 20 day and a hydraulic retention time of 15 hr was higher compared to a SRT of 10 day and at the same HRT. The results also showed that the yield (Y), the endogenous decay coefficient (kd), the maximum specific growth rate (μmax), and the saturation constant (Ks) for styrene and ethylbenzene as substrate were 0.60 and 0.60 mg/mg, 0.25 and 0.25 day−1, 0.188 and 0.363 h-1, and 0.146 and 2.82 mg /l, respectively. Furthermore, ethylbenzene was more appropriate as a source of carbon to activated sludge in the membrane bioreactor than the styrene which had a lower μmax than ethylbenzene.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"20 1","pages":"207-214"},"PeriodicalIF":0.0,"publicationDate":"2017-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91181550","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}
Peyman Mahmoodi, M. Farhadian, A. Р. Nazar, R. Bashiri
The interaction between the ions and the charge of membranes can affect the efficiency of pollutant removal. The present study investigated the removal efficiency of hexavalent chromium and nitrate ions from both actual and synthetic contaminated water via two different commercial spiral wound polyamide nanofilters. In addition, the interaction of ions under different experimental conditions was investigated by using a Box-Behnken design (BBD). The Box–Behnken design optimized the contributing factors which included pH (5-9), the initial concentration of Cr (VI) (0.05-5 mg/L) and the initial concentration of nitrate (40-160 mg/L). The maximum removal efficiency of both Cr (VI) and nitrate was achieved at a pH of 9.0, as 99 % and 90 % for the Iranian nanofilter (NF-I) and 98 % and 82 % for the Korean nanofilter (NF-K), respectively. The results also indicated that as the initial concentration of Cr (VI) increased, the removal efficiency was enhanced while the removal efficiency of nitrate decreased according to the pH. However, by increasing the initial concentration of nitrate, the removal efficiency of both the Cr (VI) and nitrate increased. For actual water samples at an optimum pressure of 0.6 Mpa (NF-K) and 0.8 Mpa (NF-I), the removal efficiency of Cr(VI) and nitrate obtained was 95% and 76 % for the NF-K and 97 % and 86 % for the NF-I, respectively.
{"title":"Effect of anions interaction on the removal efficiency of nanofilters for the potable water treatment","authors":"Peyman Mahmoodi, M. Farhadian, A. Р. Nazar, R. Bashiri","doi":"10.22104/AET.2017.470","DOIUrl":"https://doi.org/10.22104/AET.2017.470","url":null,"abstract":"The interaction between the ions and the charge of membranes can affect the efficiency of pollutant removal. The present study investigated the removal efficiency of hexavalent chromium and nitrate ions from both actual and synthetic contaminated water via two different commercial spiral wound polyamide nanofilters. In addition, the interaction of ions under different experimental conditions was investigated by using a Box-Behnken design (BBD). The Box–Behnken design optimized the contributing factors which included pH (5-9), the initial concentration of Cr (VI) (0.05-5 mg/L) and the initial concentration of nitrate (40-160 mg/L). The maximum removal efficiency of both Cr (VI) and nitrate was achieved at a pH of 9.0, as 99 % and 90 % for the Iranian nanofilter (NF-I) and 98 % and 82 % for the Korean nanofilter (NF-K), respectively. The results also indicated that as the initial concentration of Cr (VI) increased, the removal efficiency was enhanced while the removal efficiency of nitrate decreased according to the pH. However, by increasing the initial concentration of nitrate, the removal efficiency of both the Cr (VI) and nitrate increased. For actual water samples at an optimum pressure of 0.6 Mpa (NF-K) and 0.8 Mpa (NF-I), the removal efficiency of Cr(VI) and nitrate obtained was 95% and 76 % for the NF-K and 97 % and 86 % for the NF-I, respectively.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"20 1","pages":"197-205"},"PeriodicalIF":0.0,"publicationDate":"2017-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87533278","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}
Hakimeh Sharififard, Mahboubeh Nabavinia, M. Soleimani
The aim of this study was to evaluate the adsorption capacity of the novel coated activated carbon by chitosan for removal of Cr (VI) and Cd (II) ions from single and bi-solute dilute aqueous solutions. In addition, the adsorption abilities of activated carbon (AC), chitosan (CH) and chitosan / activated carbon composite (CHAC) have been compared. Adsorption studies were performed in a batch system, and the effects of various operating parameters such as solution pH, particle size and the dose of adsorbent were considered for removal of Cr (VI) and Cd (II) by Taguchi method. Equilibrium experimental data were well fitted to Langmuir isotherm for single and bi-solute solutions. The adsorption capacities of AC and CH adsorbents have improved by synthesis CHAC composite. As it was expected, competitive adsorption of metal ions on the CHAC surface led to reducing the adsorption capacity from 90.9 mg g-1 to 41.94 mg g-1 for Cr (VI) and 52.63 mg g-1 to 30.21 mg g-1 for Cd (II) ions, respectively. The adsorption capacities for the metal solution–adsorbent systems are in the order Cr (VI) > Cd (II). The kinetic studies indicated that the adsorption process was best described by the pseudo-second-order kinetics for single and bi-solute solutions.
{"title":"Evaluation of adsorption efficiency of activated carbon/chitosan composite for removal of Cr (VI) and Cd (II) from single and bi-solute dilute solution","authors":"Hakimeh Sharififard, Mahboubeh Nabavinia, M. Soleimani","doi":"10.22104/AET.2017.484","DOIUrl":"https://doi.org/10.22104/AET.2017.484","url":null,"abstract":"The aim of this study was to evaluate the adsorption capacity of the novel coated activated carbon by chitosan for removal of Cr (VI) and Cd (II) ions from single and bi-solute dilute aqueous solutions. In addition, the adsorption abilities of activated carbon (AC), chitosan (CH) and chitosan / activated carbon composite (CHAC) have been compared. Adsorption studies were performed in a batch system, and the effects of various operating parameters such as solution pH, particle size and the dose of adsorbent were considered for removal of Cr (VI) and Cd (II) by Taguchi method. Equilibrium experimental data were well fitted to Langmuir isotherm for single and bi-solute solutions. The adsorption capacities of AC and CH adsorbents have improved by synthesis CHAC composite. As it was expected, competitive adsorption of metal ions on the CHAC surface led to reducing the adsorption capacity from 90.9 mg g-1 to 41.94 mg g-1 for Cr (VI) and 52.63 mg g-1 to 30.21 mg g-1 for Cd (II) ions, respectively. The adsorption capacities for the metal solution–adsorbent systems are in the order Cr (VI) > Cd (II). The kinetic studies indicated that the adsorption process was best described by the pseudo-second-order kinetics for single and bi-solute solutions.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"47 1","pages":"215-227"},"PeriodicalIF":0.0,"publicationDate":"2017-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78751828","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}
A bioreactor refers to any manufactured or engineered device that supports a biologically active environment. These kinds of reactors are designed to treat wastewater treatment. Volumetric mass transfer coefficient and the effect of superficial gas velocity, as the most important operational factor on hydrodynamics, in three-phase airlift reactors are investigated in this study. The experiments for the external airlift reactor were carried out at a 0.14 downcomer to riser cross-sectional area ratio, and for the internal reactor at 0.36 and 1. Air and water were used as the gas and liquid phases, respectively, as well as activated carbon/sludge particles as the solid phase. Increasing the superficial gas velocity resulted in greater liquid circulation velocity, gas hold-up, and volumetric mass transfer coefficient; increasing the suspended activated carbon particles resulted in a decreased concentration of activated sludge, downcomer to riser cross sectional area ratio, liquid velocity, gas hold-up and volumetric mass transfer coefficient. The maximum gas hold-up was 0.178 which was attained in the external airlift reactor with a 1 Wt. % of activated sludge at a gas superficial velocity of 0.25 (m/s). The maximum volumetric mass transfer coefficient was 0.0485 (l/s) that was observed in the external airlift reactor containing activated carbon with a 0.00032 solid hold-up. A switch was observed in the activated sludge airlift reactor flow regime at gas velocities higher than 0.15 (m/s) and 0.18 (m/s) in the activated carbon airlift reactors.
{"title":"Hydrodynamics and mass transfer inthree-phase airlift reactors for activated Carbon and sludge filtration","authors":"M. Salehi, Nasrin Hakimghiasi","doi":"10.22104/AET.2017.454","DOIUrl":"https://doi.org/10.22104/AET.2017.454","url":null,"abstract":"A bioreactor refers to any manufactured or engineered device that supports a biologically active environment. These kinds of reactors are designed to treat wastewater treatment. Volumetric mass transfer coefficient and the effect of superficial gas velocity, as the most important operational factor on hydrodynamics, in three-phase airlift reactors are investigated in this study. The experiments for the external airlift reactor were carried out at a 0.14 downcomer to riser cross-sectional area ratio, and for the internal reactor at 0.36 and 1. Air and water were used as the gas and liquid phases, respectively, as well as activated carbon/sludge particles as the solid phase. Increasing the superficial gas velocity resulted in greater liquid circulation velocity, gas hold-up, and volumetric mass transfer coefficient; increasing the suspended activated carbon particles resulted in a decreased concentration of activated sludge, downcomer to riser cross sectional area ratio, liquid velocity, gas hold-up and volumetric mass transfer coefficient. The maximum gas hold-up was 0.178 which was attained in the external airlift reactor with a 1 Wt. % of activated sludge at a gas superficial velocity of 0.25 (m/s). The maximum volumetric mass transfer coefficient was 0.0485 (l/s) that was observed in the external airlift reactor containing activated carbon with a 0.00032 solid hold-up. A switch was observed in the activated sludge airlift reactor flow regime at gas velocities higher than 0.15 (m/s) and 0.18 (m/s) in the activated carbon airlift reactors.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"40 1","pages":"179-184"},"PeriodicalIF":0.0,"publicationDate":"2017-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85084167","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}
The objective of this study was to investigate the growth rate of Chlorella vulgaris for CO2 biofixation and biomass production. Six mathematical growth models (Logistic, Gompertz, modified Gompertz, Baranyi, Morgan and Richards) were used to evaluate the biomass productivity in continuous processes and to predict the following parameters of cell growth: lag phase duration (λ), maximum specific growth rate (μmax), and maximum cell concentration (Xmax). The low root-mean-square error (RMSE) and high regression coefficients (R2) indicated that the models employed were well fitted to the experiment data and it could be regarded as enough to describe biomass production. Using statistical and physiological significance criteria, the Baranyi model was considered the most appropriate for quantifying biomass growth. The biological variables of this model are as follows: μmax=0.0309 h−1, λ=100 h, and Xmax=1.82 g/L.
{"title":"Predictive modeling of biomass production by Chlorella vulgaris in a draft-tube airlift photobioreactor","authors":"M. Mansouri","doi":"10.22104/AET.2017.433","DOIUrl":"https://doi.org/10.22104/AET.2017.433","url":null,"abstract":"The objective of this study was to investigate the growth rate of Chlorella vulgaris for CO2 biofixation and biomass production. Six mathematical growth models (Logistic, Gompertz, modified Gompertz, Baranyi, Morgan and Richards) were used to evaluate the biomass productivity in continuous processes and to predict the following parameters of cell growth: lag phase duration (λ), maximum specific growth rate (μmax), and maximum cell concentration (Xmax). The low root-mean-square error (RMSE) and high regression coefficients (R2) indicated that the models employed were well fitted to the experiment data and it could be regarded as enough to describe biomass production. Using statistical and physiological significance criteria, the Baranyi model was considered the most appropriate for quantifying biomass growth. The biological variables of this model are as follows: μmax=0.0309 h−1, λ=100 h, and Xmax=1.82 g/L.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"6 1","pages":"119-126"},"PeriodicalIF":0.0,"publicationDate":"2017-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84322542","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}
This study investigated the photo-degradation of methyl orange (MO) as a type of azo dye using a CuO/α-Fe2O3 nanocomposite. A CuO/α-Fe2O3 powder with a crystalline size in the range of 27-49 nm was successfully prepared using simple co-precipitation along with a sonication method. The characterization of the synthesized sample was done via XRD, FE-SEM, EDS, FTIR and DRS analyses. The Tauc equation revealed that the band gap of the nano composite in the direct mood was 2.05 ev, which is in the visible light range. The effect of operating factors containing dye concentration, photocatalyst dosage and pH on dye degradation efficiency was measured. Response Surface Method (RSM) was employed to specify the parameter effects. The photocatalytic activity of the CuO/α-Fe2O3 nanocomposite was evaluated by degradation of MO under visible light irradiation. The results showed that the pH value played a very effective role in the dye degradation process efficiency. Also, the photocatalytic degradation of MO obtained was equal to 88.47% in the optimal values.
{"title":"Synthesis, characterization and degradation activity of Methyl orange Azo dye using synthesized CuO/α-Fe2O3 nanocomposite","authors":"Mohsen Mehdipour Ghazi, M. Ilbeigi, M. Jahangiri","doi":"10.22104/AET.2017.427","DOIUrl":"https://doi.org/10.22104/AET.2017.427","url":null,"abstract":"This study investigated the photo-degradation of methyl orange (MO) as a type of azo dye using a CuO/α-Fe2O3 nanocomposite. A CuO/α-Fe2O3 powder with a crystalline size in the range of 27-49 nm was successfully prepared using simple co-precipitation along with a sonication method. The characterization of the synthesized sample was done via XRD, FE-SEM, EDS, FTIR and DRS analyses. The Tauc equation revealed that the band gap of the nano composite in the direct mood was 2.05 ev, which is in the visible light range. The effect of operating factors containing dye concentration, photocatalyst dosage and pH on dye degradation efficiency was measured. Response Surface Method (RSM) was employed to specify the parameter effects. The photocatalytic activity of the CuO/α-Fe2O3 nanocomposite was evaluated by degradation of MO under visible light irradiation. The results showed that the pH value played a very effective role in the dye degradation process efficiency. Also, the photocatalytic degradation of MO obtained was equal to 88.47% in the optimal values.","PeriodicalId":7295,"journal":{"name":"Advances in environmental science and technology","volume":"39 1","pages":"143-151"},"PeriodicalIF":0.0,"publicationDate":"2017-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76375843","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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