Removal of Cephalexin From Aqueous Solutions Using Magnesium Oxide/Granular Activated Carbon Hybrid Photocatalytic Process

In the present study, magnesium oxide/granular activated carbon (MgO/GAC) composite as a catalyst was synthesized using the sol-gel method and its catalytic potential was investigated in the presence of ultraviolet (UV) irradiation for the removal of cephalexin (CLX) in a batch mode reactor. Then, the characterization of the MgO/GAC composite was determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Next, the effect of operational parameters was evaluated, including the pH of the solution (3-11), the dosage of composite (1-6 g/L), initial CLX concentration (20-100 mg/L), and contact time (10-60 minutes). The maximum CLX degradation with an initial concentration of 20 mg/L was as high as 98% at pH=3, 4 g/L of MgO/GAC composite with UV irradiation within 60-minute contact time. In addition, the removal process of CLX could be described by the pseudofirst-order kinetic. Further, the chemical oxygen demand (COD) and total organic carbon (TOC) removal rate were 78% and, 62.3% in optimum conditions, respectively. The results indicated that the UV/MgO/GAC hybrid photocatalytic process can be considered as an efficient alternative for treating the wastewater containing CLX

Bulking Control in Complete-Mixed Activated Sludge Process Using Combination of Metallic Coagulants and Static Magnetic Fields

Metallic coagulants have been used for more coagulation and flocculation of flocs in many wastewater treatment plants (WWTPs) in all parts of the world. The integration of different methods to improve the wastewater treatment process has been considered in recent years. In this case-control study, the effects of four main coagulants (ferric chloride, ferric sulfide, alum, and poly-aluminum chloride) on sludge volume index (SVI) with and without exposure of static magnetic fields (SMFs) have been investigated. Both methods significantly reduced SVI (mL/g), but the combination of SMFs and coagulants was more effective. Ferric chloride could control bulking or reduce SVI to less than 150 mL/g at concentrations of 0.0625 to 2 g/L when the SMFs intensity of 15 mT was used. The control of bulking in other coagulants happened when SMFs were added to coagulants at 0.0625-0.125 g/L concentration of coagulants (P<0.05). With the application of SMFs, the highest reduction of SVI belonged to ferric sulfide (43.60%), followed by ferric chloride (18.40%), poly-aluminum chloride (PACl) (20.19%), and alum (19.80%). Without the application of SMFs, the highest reduction of SVI belonged to ferric chloride (38.36%), followed by alum (34.94%), PACl (25.43%), and ferric sulfide (6.69%)

Survey of Knowledge, Attitude, and Performance of Students at Hamadan University of Medical Sciences Regarding Solid Wastes Recycling

This descriptive, cross-sectional study aimed to assess the correlations between the knowledge, attitude, and performance of the students of Hamadan University of Medical Sciences, Iran, regarding waste recycling in 2020-2021. A questionnaire was used for data collection, and the sample population consisted of 70 male and female students. Data were analyzed using SPSS version 21 by Mann-Whitney and Kruskal-Wallis (α=0.05). The sample population included 87.1% women and 12.9% men. In total, 22.9% of students received special training to recognize the adverse effects and management of waste while 77.1% of them received no training. In addition, 22.9% of students reported the contraction of infectious diseases in themselves or others around them due to contact with garbage or contaminated equipment. The marital status had a significant difference with the amount of knowledge of the studied students for determining the type of awareness regarding the importance of recycle waste while gender represented no substantial difference in this regard. Based on the results, a positive correlation was observed between attitude and awareness, as well as the performance with knowledge and attitude. Knowledge, attitude, and performance are meaningful predictors of waste management. According to the results, the importance of waste management should be emphasized to student in the community in terms of the current health conditions. It also seems that the influential factors in waste management should be fully identified in interventional programs, and appropriate interventions should be planned and implemented accordingly

p-Chlorophenol Oxidation in Industrial Effluent by Ultrasonic/Fenton Technology

Phenolic compounds have become a cause for of worldwide concern due to their persistence, toxicity and health risks. Hence, removal of these pollutants from aqueous effluents is an important practical problem. Ultrasonic technology may be used for water and wastewater treatment as an advanced oxidation process. Application of this technology, leads to the decomposition of many organic compounds during cavitation process. The degradation of 4-chlorophenol in aqueous solution under sonolysis at 45 kHz coupled with fFenton process was is investigated. The oxidation rate was influenced by many factors, such as the pH value, the amount of hydrogen peroxide, catalyst (FeSO4) and initial p-chlorophenol concentration. The experimental results showed that the decomposition of p-chlorophenol was affected by the various reaction conditions. The optimum conditions obtained for the best degradation rate were pH=3, H2O2 concentration of 0.05 mol/L and 0.025 mmol/L for catalyst, respectively. Also it was observed that the degradation of p-chlorophenol depended on its initial concentratio

Removal of phenol in aqueous solutions by ferrous activated persulfate in the present of UV irradiation

Background and Objective: Organic aromatic compounds as common environmental pollutants can be existing in the effluent of different industries in concentrations ranging from trace quantities to hundreds of milligrams per liter. Phenol compounds extremely have been used in pharmaceutical, wood industry and paper and dyes industries which introduced to environment via effluents. This study was done to evaluate the efficacy of persulfate activated by Fe2+ in the present of UV for removal of phenol from aqueous solutions. Methods: This photocatalytic degradation experiment was performed in batch mode using a 2.5 L cylindrical reactor equipped with low-pressure Hg vapor lamp of 55 W for wavelength production of 253.7 nm. The effects of operating parameters such as pH of the solution (pH: 3-10), different initial persulfate concentration (10-75 mmol/l), initial Fe2+ concentration (5-30 mmol/l) and initial phenol concentration (10-100 mg/l). Concentration changes of phenol were determined using UV–VIS spectroscopy at the wavelength of 500 nm. Results: Degradation of phenol was significantly decreased with increasing of pH from 3 to 10, whereas the highest phenol removal rate was 82% at pH=3 in 45 min contact time. Also, the phenol removal rate is depending on initial persulfate and Fe2+ concentration. The degradation of phenol by this photocatalytic followed first order rate decay kinetics (R2>98%(. Under optimum operational conditions, the removal of TOC was obtained to be 61% in 45 min contact time. Conclusion: This study indicated that activation of persulfate by Fe2+ in the present of UV process could serve as a novel treatment technique for removal of phenol in aqueous solution

Removal of 2,4 Di-Chlorophenol Using Persulfate Activated with Ultrasound from Aqueous Solutions

Background: Chlorophenols are an abundant class of xenobiotic compounds which is excessively available in industrial effluent which are resist to biological degradation and stable in the environment for exceptionally long periods of time. Therefore, the removal of 2,4 di-chlorophenol (2,4 DCP) from aqueous solutions is recommended due to its toxicity and health risks. Methods: In this study, the removal of 2,4 DCP using persulfate activated with ultrasonic waves in frequency of 40 kHz was studied. The effects of operational parameters such as pH of solution (3-10), initial concentration of 2,4 DCP (50- 100mg/L), the amount of persulfate concentration (1-5 mM) and different ionic strength in different contact time were investigated. Results: Results of the study indicated that the 2,4 DCP removal rate was influenced by operational parameters such as pH of solutions, persulfate concentration, contact time and initial concentration of 2,4 DCP and is not related to ionic strength in different amount. The optimal conditions were achieved in pH=3, persulfate concentration of 4 mM and initial concentration of 50mg/L of th organic matter which more than 95% of 2,4 DCP was removed in 60 min. Conclusion: The result of this study indicated that combined ultrasonic and persulfate process in optimal conditions, as a acceptable alternative, can be used as an alternative technology for treatment of various industrial wastewater contained 2,4 DCP

2, 4-Dichlorophenol Removal from Aqueous Solution by Continuous Using of UV-LED/TiO2 Photocatalytic Process

2, 4-Dichlorophenol is one of the most common and abundant pollutants widely found in various industrial effluent. The obvious effect of this organic compound on health and environment depends on enhancing the degradation efficiency of this aqueous pollutant before wastewater being discharged into the receiving water. Therefore, in this study, removal of 2, 4-dichlorophenol from aqueous solution was investigated through using UV-LED/TiO2 process. In this experimental study, removal of 2, 4-DCP in the presence of TiO2 by using UV-LED in a bench scale reactor was examined. The effects of operational parameters such as pH (3-11), initial concentration of 2, 4-DCP (50-200mg/L), TiO2 concentration (0.003-0.025mol/L) and ionic strength were evaluated. The results indicated that removal of 2, 4-DCP was influenced by different operational parameters. The highest 2, 4-DCP removal rate were obtained at pH=3 by adding 0.012 mol/L of TiO2 to solution with an initial concentration of 50mg/L of 2, 4-DCP which more than 95.82% of 2, 4-DCP was removed. While UV-LED and TiO2 were used separately, the 2, 4-DCP removal efficiency was 32.11% and 36.56%, respectively. Also, the results indicated that maximum COD removal rate was 71.5% in optimum condition and also indicated lack of impact on ionic strength changes for removal of organic material. The results indicated that combined TiO2/UV-LED process in optimal conditions can be used as a new technology for treatment of various industrial wastewater containing 2, 4-DCP

Removal of Pentachlorophenol Using Microwave Assisted Persulfate from Synthetic Wastewater

Pentachlorophenol (PCP) is an important class of environmental pollutants which is excessively used in industry in spite of strong evidence about its hazards. Therefore, the removal of PCP from aqua solution is recommended due to its toxicity and health risks. In the present study, the removal of PCP using a modified domestic microwave (MW) oven alone and in combination with persulfate (MW/PS) was investigated. The effects of operational parameters such as pH of solution, the power of microwave radiations and the amount of persulfate concentration were studied. A spectrophotometer was used for determining of the concentration of pentachlorophenol. The experimental results showed that the removal of PCP was influenced by many factors, such as the pH value, the amount of persulfate and microwave power. The optimum conditions for the best removal rate were obtained at pH=11, a persulfate concentration of 0.02mol/L and microwave irradiation power of about 600W for MW/PS system at constant PCP concentration.  Also, the direct degradation results showed that the removal of PCP was 2% in MW system without PS after 30 min of MW irradiation. The removal of PCP by MW/PS and MW alone were follow first order rate decay kinetics and the rate constants were 0.093 and 0.00066 min-1, respectively

Simultaneous Removal of Turbidity and Humic Acid Using Electrocoagulation/Flotation Process in Aqua Solution

In this study, the applicability of the Electrocoagulation/Flotation (ECF) process in batch operation was investigated for the simultaneous removal of turbidity and Humic acid (HA) using Fe and Al electrodes. The effects of solution pH (3 - 12), electrical potentials (10 - 30 V), initial turbidity concentration (300 - 1200 NTU), and reaction time (10 - 30 minutes) with or without HA were investigated in an attempt to achieve higher turbidity removal efficiency. The batch experimental results revealed that with initial turbidity of 300 NTU, at voltage of 30 V, after 30 minutes reaction times, and at pH values of 6 and 8, the ECF process for Fe and Al electrodes removed over 97% and 88% of turbidity, respectively. The percentage of turbidity removal from solution dropped with a decrease in voltages for both electrodes. The results displayed that the Fe-Fe electrode arrangement attained the highest performance for turbidity removal rate. As a result, ECF process was shown to be a very efficient, cost-effective, and promising process for efficient treatment of high turbid water. Regarding HA, the results showed that in ECF process over 67% and 43% of UV254 has been removed for Al and Fe electrodes, respectively at the optimum pH, 30 minutes reaction time and 30 V applied voltage. Thus, it can be considered that Fe and Al are the best electrodes for removing turbidity and HA, respectively

Effect of Chitosan as a Coagulant Aid Combined With Poly Aluminum Chloride Removing of Turbidity From Drinking Water

Chitosan, a biodegradable polymer, is used as an eco-friendly coagulant in a wide variety of applications in water and wastewater treatment. The present study aimed to investigate the effect of chitosan as a coagulant aid combined with poly aluminum chloride (PAC) to enhance coagulating efficiency for bentonite suspensions. A conventional jar test apparatus was used for the tests. The effect of various operational parameters, such as initial pH of the solution (5-9.5), dosage of chitosan (0.5-3.5 mg/L), dosage of PAC (5-35 mg/L) and initial turbidity (50-200 NTU) were investigated. The maximum turbidity removal rates were obtained as pH 8.5 for PAC and pH 7.5 for combined PAC and chitosan (CPC). The coagulating efficiency of bentonite using PAC and CPA was found to decrease with an increase in the pH value of the solutions. The maximum turbidity removal rate was achieved in coagulating by PAC (30 mg/L) alone, and PAC (20 mg/L) combined with chitosan (2.5 mg/L) as coagulant aid with the removal rate of 87% and 96%, respectively. The optimum dosage of chitosan required to obtain the highest removal rate was 2.5 mg/L. Hence, using chitosan as a coagulant aid can not only reduce the required amount of coagulant (35%) but can also enhance the removal turbidity efficiency