The Effect of Organic Loading on Propylene Glycol Removal Using Fixed Bed Activated Sludge Hybrid Reactor

Propylene glycol is discharged to the surface and underground waters and vicinity soils via industrial wastewater effluents, posing many health and environmental risks. The main goal of this study was to remove propylene glycol from synthetic wastewater in a fixed bed activated sludge reactor. To observe the effects of organic loading on bioreactor performance, the organic loading was increased by two sequencing stages: first by hydraulic retention time (HRT) depletion and second via propylene glycol concentration increase. Propylene glycol removal efficiency in HRTs of 8, 6, 4 and 2 h was 95.86, 95.12, 93.96 and 79.08 % respectively. A constant HRT of 6 h was selected for the second stage; propylene glycol concentrations of 500, 1000, 1500, 2000 and 2500 mg L–1 were used. The removal efficiency for these concentrations was 95.12, 95.95, 88.54, 75.95 and 35.69 % respectively. Thus, the integrated fixed bed activated sludge reactor is an efficient, viable and promising technology for treating wastewaters containing propylene glycol

Adsorption and magnetic separation of lead from synthetic wastewater using carbon/iron oxide nanoparticles composite

Background and purpose: Removal of lead as a toxic metal from contaminated water resources is necessary due to the dangerous effect of lead. One of the most effective methods of removal is the adsorption process. The aim of this study was adsorption and magnetic separation of lead from synthetic wastewater using iron oxide nanoparticles and carbon (ION/C) composite Material and Methods: In this study nanoparticles of iron oxide (ION) were used as a source of iron for magnetic separation of powder activated carbon from solution samples. The physical and surface properties of the adsorbent were studied along with influencing factors (pH, contact time, adsorbent dosage, initial lead concentration, and temperature) on the adsorption process. Kinetic equations and equilibrium isotherms studies were also conducted. Results: The size of ION and specific surface area of ION/C were found to be 30-80 nm and 671.2 m2/g, respectively. We observed that the adsorption process reached equilibrium at 60 min and pH=6and adsorption efficiency increased by increasing the amount of adsorbent and temperature. Maximum adsorption capacity based on Langmuir isotherms was obtained 67.1mg/g at 50 °C. Conclusion: According to this study it is believed that magnetized active carbon by keeping its physical and surface properties could be a suitable method to solve some related problems including separation and filtration

Powder activated carbon/Fe3O4 hybrid composite as a highly efficient heterogeneous catalyst for Fenton oxidation of tetracycline: Degradation mechanism and kinetic

In this work, we prepared and used a composite of powder activate carbon/Fe3O4 magnetic nanoparticles (PAC/Fe3O4 MNPs) as a heterogeneous catalyst to remove tetracycline (TC) from aqueous solution. By using XRD, BET, VSM, SEM, TEM and EDX techniques, also, we tried to characterize the catalyst. The effects of pH, H2O2, catalyst dosages and also initial TC concentration on the degradation process were assessed. Based on the results, it was indicated that at low pH values and initial TC concentrations, the efficiency of the process is higher than the other values and concentrations studied in this work. Under the ambient conditions and setting the initial pH value and TC concentration at respectively 3.0 ± 0.2 and 10 mg L-1, the optimal dosage of reagents were recorded to be 0.3 g L-1 catalyst and 80.0 mM H2O2. The values of observed rate constants, kobs, increased by increasing the catalyst loading in the system; however, these values decreases when the initial TC concentration was increased. Our findings indicated that all of TC concentration was nearly degraded during the 180 min reaction. Regarding the reusability of PAC/Fe3O4 MNPs, the results showed that TC and TOC removal efficiencies of 94.5 and 32.3, respectively, can be achieved after four consecutive runs. By conducting the stability experiments, it was confirmed that PAC/Fe3O4 MNPs is a promising and effective catalyst in Fenton reactions and can be used to treat TC-contaminated water with very low loss of catalytic activity. © 2015 The Royal Society of Chemistry

Effectiveness of biostimulation through nutrient content on the bioremediation of phenanthrene contaminated soil

Bioremediation has shown its applicability for removal of polycyclic aromatic hydrocarbons (PAHs) from soil and sediments. In the present study, the effect of biostimulation on phenanthrene removal from contaminated soil via adding macro and/or micronutrients and trace elements was investigated. For these purposes three macro nutrients (as N, P and K), eight micronutrients (as Mg, S, Fe, Cl, Zn, Mn, Cu and Na) and four trace elements (as B, Mo, Co and Ni) in 11 mineral salts (MS) as variables were used. Placket-Burman statistical design was used to evaluate significance of variables (MS) in two levels of high and low. A consortium of adapted microorganisms with PAHs was used for inoculation to the soil slurry which was spiked with phenanthrene in concentration of 500 mg/kg soil. The optimal reduction resulted when a high level of macro nutrient in the range of 67-87 and low level of micro nutrient in the range of 12-32 were used with the nitrogen as the dominant macronutrient. The Pareto chart showed that NH4NO3 was the most effective variable in this experiment. The effect of elements on phenanthrene biodegradation showed following sequence as N > K > P > Cl > Na > Mg. Effectiveness of the other elements in all runs was less than 1. The type and concentration of nutrient can play an important role in biodegradation of phenanthrene. Biostimulation with suitable combination of nutrient can enhance bioremediation of PAHs contaminated soils. ©2014 Kalantary et al

Experimental design approach to the optimization of PAHs bioremediation from artificially contaminated soil: Application of variables screening development

Background: The effectiveness of bioremediation systems for PAH-contaminated soil may be constrained by physicochemical properties of contaminants and environmental factors. Information on what is the most effective factor in bioremediation process is essential in the decision of what stimulations can be taken to assist the biodegradation efficacy. Methods: In this study, four factors of surfactant (Tween 80), humic acid (HA), salinity and nutrients in a 24 full factorial design were screened in bioremediation of phenanthrene contaminated soil by using a consortium of bacteria. Results: Between the employed levels of the factors only salinity had not significant effect. Optimal concentrations of surfactant, HA and nutrient were obtained by a response surface design. For phenanthrene biodegradation, a central composite face centred design (CCFD) showed that nutrient, surfactant and HA concentrations had highly significant, significant and insignificant effects, respectively. The best conditions with 87.1 phenanthrene biodegradation were 150 mg HA/Kg soil, 12.68 μg/L surfactant, and nutrients as K2HPO4, 0.8; KH2PO4, 0.2 and KNO3, 1 g/L. A high similarity was between the model prediction and experimental results. Conclusions: This study showed that nutrient with 81.27 efficiency could be considered as the most effective factor for practical implications of bioremediation process for PAHs contaminated soil cleanup strategies. © 2015 Ravanipour et al.; licensee BioMed Central

Performance evaluation of enhanced SBR in simultaneous removal of nitrogen and phosphorous

BACKGROUND: Simultaneous nitrogen, phosphorous and COD removal in a pilot-scale enhanced Sequencing Batch Reactor (eSBR) was investigated. METHODS: The reactor consisted of a pre-anoxic zone and internal recycle and was fed with synthetic wastewater. The study was performed by operating the reactor in 6-hour cycles in three different operational modes during a time frame of 279 days. RESULTS: Under the best operational conditions, the average removal rate of COD, TN, and TP were obtained as 93.52, 88.31, and 97.56%, respectively. CONCLUSIONS: A significant denitrifying phosphorus removal (more than 80%) occurred at run1 and 3 which started the cycle under anoxic condition

Optimization of dimethyl phthalate degradation parameters using zero-valent iron nanoparticles by response surface methodology: Determination of degradation intermediate products and process pathway

Background and purpose: Phthalic acid esters (PAEs) are a group of organic compounds that are used as additives in plastic industry. Among PAEs, dimethyl phthalate (DMP), the simplest compound in phthalates, is an aromatic pollutant that disturbs endocrine function. The aim of this study was to assess the effect of zero-valent iron nanoparticles (NZVI) on the DMP degradation. Materials and methods: NZVI were prepared by reduction of ferric chloride using sodium borohydride. Physical properties of nanoparticles were determined using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), and Vibrating Sample Magnetometer (VSM). Then, the effect of pH, DMP concentrations, the amount of NZVI, and contact time were investigated on DMP removal efficiency. Response surface methodology based on Box- Behnken was used to study the interaction between variables. Results: Maximum efficiency (99) of DMP removal by NZVI was achieved in optimum conditions (pH=3, NZVI dosage =0.6 g/l, DMP concentration = 2 mg/l, and contact time= 65 min). The Box-Behnken analysis confirmed that pH and NZVI dosage have had the highest and lowest effect in the process of DMP removal by NZVI, respectively. Conclusion: According to findings, NZVI in small amounts have a proper efficiency in DMP removal. Also, DMP degradation efficiency did not change much, after being used in five consecutive cycles of degradation reactions. This shows a potential application prospect of the synthesized NZVI in real water treatment. © 2015 Journal of Mazandaran University of Medical Sciences. All Rights Reserved

Optimization of dimethyl phthalate degradation parameters using zero-valent iron nanoparticles by response surface methodology: Determination of degradation intermediate products and process pathway

Background and purpose: Phthalic acid esters (PAEs) are a group of organic compounds that are used as additives in plastic industry. Among PAEs, dimethyl phthalate (DMP), the simplest compound in phthalates, is an aromatic pollutant that disturbs endocrine function. The aim of this study was to assess the effect of zero-valent iron nanoparticles (NZVI) on the DMP degradation. Materials and methods: NZVI were prepared by reduction of ferric chloride using sodium borohydride. Physical properties of nanoparticles were determined using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), and Vibrating Sample Magnetometer (VSM). Then, the effect of pH, DMP concentrations, the amount of NZVI, and contact time were investigated on DMP removal efficiency. Response surface methodology based on Box- Behnken was used to study the interaction between variables. Results: Maximum efficiency (99) of DMP removal by NZVI was achieved in optimum conditions (pH=3, NZVI dosage =0.6 g/l, DMP concentration = 2 mg/l, and contact time= 65 min). The Box-Behnken analysis confirmed that pH and NZVI dosage have had the highest and lowest effect in the process of DMP removal by NZVI, respectively. Conclusion: According to findings, NZVI in small amounts have a proper efficiency in DMP removal. Also, DMP degradation efficiency did not change much, after being used in five consecutive cycles of degradation reactions. This shows a potential application prospect of the synthesized NZVI in real water treatment. © 2015 Journal of Mazandaran University of Medical Sciences. All Rights Reserved

Simultaneous removal of Lead and Aniline from industrial wastewater using magnetic composite of Fe3O4/PAC

Background and aims: Today, using magnetic adsorbents and the subsequent magnetically separation of pollutants is highly considered by researchers due to it's ease of use, low cost and rapid results. Therefore the aim of this study was the synthesis of a magnetic composite of activated carbon/Fe3O4 nanoparticles (Fe3O4/PAC), and its application as a magnetic adsorbent for simultaneous removal of lead and aniline from industrial wastewater. Methods: Physical, surface and morphological features of the adsorbent, as well as, the performance of adsorption process were studied in a batch system by investigating the changes in parameters such as pH, contact time, adsorbent and adsorbate concentrations, and temperature. In order to explain experimental data, Freundlich and Langmuir equilibrium isotherms, in addition to Lagergren, Ho and Elovich kinetic equations were applied. Results: Results of this study demonstrated that 90 of lead and 94 of aniline were removable by the synthesized adsorbent under the optimal conditions (pH 6, a contact time 60 min and adsorbent dose of 2 g/L). Experimental data from adsorption were better described by both Langmuir and Freundlich isotherm models, and the pseudo-second-order kinetic model. Conclusion: According to these results, it can be claimed that Fe3O4/PAC had an effective adsorption capacity for simultaneous adsorption of lead and aniline, and thus, it is recommended to optimally use Fe3O4/PAC as an efficient adsorbent for treatment of wastewaters containing these pollutants

Effectiveness of biostimulation through nutrient content on the bioremediation of phenanthrene contaminated soil

Bioremediation has shown its applicability for removal of polycyclic aromatic hydrocarbons (PAHs) from soil and sediments. In the present study, the effect of biostimulation on phenanthrene removal from contaminated soil via adding macro and/or micronutrients and trace elements was investigated. For these purposes three macro nutrients (as N, P and K), eight micronutrients (as Mg, S, Fe, Cl, Zn, Mn, Cu and Na) and four trace elements (as B, Mo, Co and Ni) in 11 mineral salts (MS) as variables were used. Placket-Burman statistical design was used to evaluate significance of variables (MS) in two levels of high and low. A consortium of adapted microorganisms with PAHs was used for inoculation to the soil slurry which was spiked with phenanthrene in concentration of 500 mg/kg soil. The optimal reduction resulted when a high level of macro nutrient in the range of 67-87 and low level of micro nutrient in the range of 12-32 were used with the nitrogen as the dominant macronutrient. The Pareto chart showed that NH4NO3 was the most effective variable in this experiment. The effect of elements on phenanthrene biodegradation showed following sequence as N > K > P > Cl > Na > Mg. Effectiveness of the other elements in all runs was less than 1. The type and concentration of nutrient can play an important role in biodegradation of phenanthrene. Biostimulation with suitable combination of nutrient can enhance bioremediation of PAHs contaminated soils. ©2014 Kalantary et al