ghasem azarian

To facilitate the wastewater recycling process while adhering to environmental and industrial regulations, it becomes imperative to meet stringent standards. This necessitates the effective elimination of organic substances, with particular emphasis on nitrogen-based compounds. To this end, activated sludge methods, particularly the step-feed biological nitrogen removal (SFBNR) process, are employed. Although various operational measures are employed in SFBNR systems, including the elimination of complex substrates, modifications in aeration conditions, the utilization of piston hydraulic flow, and the appropriate distribution of substrates, these systems remain susceptible to the excessive growth of filamentous bacteria. The current study aimed to examine the change in the distribution of the hydraulic flow entering this system on a real scale over a period of five years. It was observed that the quality of sludge settling improved and accordingly the overgrowth of filamentous Microthrix parvicella declined, thereby enhancing the quality of the effluent.

Amoxicillin antibiotic is one of the antibiotics which is used in medicine and veterinary medicine to treat bacterial infectious diseases. In this study, a special electrochemical cell design was used as it could integrate the process units and the operation units to reduce COD and amoxicillin antibiotic residues from the wastewater of Alimoradian Hospital. Also, to optimize the operational parameters, the central composite design of response surface methodology (RSM) was used.

This experimental study was conducted in two parts. In the first stage, synthetic wastewater was prepared from Amoxicillin antibiotics to investigate the effect of various parameters such as reaction time, initial antibiotic concentration, current density, and pH on the efficiency of the method. In the second stage, the efficiency of the method in removing the antibiotic and reducing COD from the actual wastewater of Alimoradian hospital was evaluated.

Using the RSM, the optimal conditions of the laboratory findings were determined as follows: reaction time = 30 min, pH = 7.5, current density = 2.31 mA/cm2, and initial concentration of amoxicillin = 54.66 mg/L. Under these conditions, the removal amount of amoxicillin was 90.56%. The results also showed that under optimal conditions, the removal rate of COD and TOC from synthetic wastewater is 65.5% and 44.5%, respectively, and in the effluent of Alimoradian hospital is 47.7% and 38%, respectively. The reason for this difference is probably due to the presence of some resistant compounds in the real wastewater.

This experimental study showed that the combined electrocoagulation process can be a more effective method in removing the amoxicillin antibiotic and COD from aqueous solutions and hospital wastewater.

Azandarian industrial zone with about 40 active silica crushing units is one of the largest industrial area in Hamadan province, Iran.

In this study, the personal exposure of workers in the activated silica crushing units was measured. Assessing the risk of mortality due to exposure to Respirable Crystalline Silica (RCS) in the workplace was then estimated through measuring the personnel exposure in accordance with the National Institute for Occupational Safety and Health (NIOSH) 7601 method. Moreover, the mortality rate of lung cancer and risk of mortality due to exposure to RCS were estimated.

Based on the results, the average exposure of employees to RCS in the crushing units was in the range of 1.70 -0.14 mg/m3. As observed, the lowest and highest exposure was obtained for the admission unit and sandstone, respectively. In general, it can be inferred that in all studied occupation positions, the exposure level was higher than the recommended standard (0.25 mg/m3). As can be seen, the carcinogenic risk level for the exposed workers was in the range 2-26/1000. The results of risk assessment showed that the highest risk level was related to the stamping machine operator unit and the lowest was related to the administrative unit.

Therefore, the workers working in high-risk units such as stamping machine operator and stone separation operator are more likely to suffer from adverse health complications such as silicosis, lung cancer and other respiratory complications.

Since large amounts of agricultural wastes are produced in Iran and these wastes have lignocellulosic nature, the current study was performed to survey the adsorption performance of methylene blue dye from aqueous solutions by means of raw and modified cantaloupe peel. The adsorbents used were characterized using techniques like scanning electron microscope (SEM), as well as Fourier transform infrared spectroscopy (FTIR). In this study, the effects of a few key variables including pH, reaction time, dye concentration, adsorbent dosage and temperature on the adsorption performance were investigated. Optimum values were attained at 0.04 and 0.08 g doses of modified and raw cantaloupe peel, pH of 7 after mixing for 120 and 90 minutes for raw and modified cantaloupe peel, respectively. The equilibrium information was fitted to the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich equations and the respective data for all models were tested. An increase in adsorbent dose and temperature caused the efficiency to rise. The mechanism and rate of adsorption were ascertained by analyzing the experimental data at various contact times according to traditional kinetic equations: pseudo-first-order and second order, Elovich, and intra-particle diffusion. The findings illustrated that the data accorded closely with the pseudo-second-order model. Moreover, it was found that these wastes can be applied to remove environmental pollutants, particularly methylene blue dye.

Dear Editor In recent days, coronavirus disease (COVID-19) as a viral infection caused by the SARS-Cov-2 virus has become a pandemic disease and has created critical conditions worldwide [1]. According to previous studies on pathogenic viruses associated with acute respiratory distress syndrome, each virus has a specific virulence dose, which it is about 2×103-3×103 viral particles for the influenza virus. Given the emergence of the SARSCov-2 virus and no complete information on its virulence dose, it is clear that its very low virulence dose can cause its rapid spread. Regarding the effectiveness of the use of simple cloth filter masks, it can be stated that these masks provide relative safety depending on their type and structure [2]. In this regard, Blachere et al., reported that in multi-stage sampling of influenza viruses, 46% of the viruscontaining particles are trapped in the first filter layer of the sampler with a diameter of 4 microns, 49% of the viral particles are trapped in the second layer filter with a diameter 1 to 4 microns and only 1% of viruses are trapped in the last layer filter with a diameter of about 1 micron [2-4]. Coughing, sneezing, speaking, and breathing create a cloud of particles in the air with varying diameters ranging from a few millimeters to <1 micrometer. Large droplets (larger than 50 microns in diameter) are immediately deposited to the ground. Most respiratory droplets containing viruses are in this size range. Medium droplets (10 to 50μm) remain in the air for several minutes. Small particles (<10μm), including droplets nucleated by larger particles, can evaporate for hours and can be easily inhaled deep into the respiratory tract. On the other hand, the SARS-Co2 virus remains alive in the airborne aerosols for 3 hours [2, 4]. Therefore, the use of simple surgical masks for patients is necessary, especially during admission, to prevent the spread of large respiratory droplet released directly during coughing and sneezing and small droplets that are produced indirectly from the evaporation of the large droplets in the hospital environment. In addition, the use of ventilation systems can prevent the high concentration of these particles in hospital environments. In this regard, it is essential to educate hospital health experts about the necessity of using ventilation systems and their performance. On the other hand, the viability of viruses in the air is highly dependent on environmental conditions. Ambient temperature is one of the key factors influencing the stability of viruses in indoor air. In the case of the influenza virus, it has been reported that a temperature of 70˚C causes complete inactivation of the virus. Also, at 5°C, the viral transmission is significantly increased. While at 30°C, the viral transmission between hosts is obviously decreased. A recent study on the Corona viruses has reported similar results [2, 5]. Moisture factor is another factor influencing the transfer of viruses in the air. The lowest transmission rate occurs at low humidity and dry air (with a relative humidity in the range 20-30%), and the highest transmission rate occurs at high relative humidity (80-50%). Therefore, viruses can be prevented by monitoring and controlling the temperature and relative humidity in hospitals by using natural and mechanical ventilation systems to adjust the temperature and humidity at the appropriate level [2, 6]. According to World Health Organization (WHO) guidelines, it is recommended to use laboratory ventilation systems and if are available heating/cooling systems, fans/air conditioning units and local cooling system with laminar air flow can be used in diagnostic laboratories of hospitals. In this case, the velocity and direction of the air flow must be laminar to prevent turbulent currents. This point should also be considered in the case of natural ventilation [7]. It is also recommended to use of biological safety hoods with HEPA filters that CAN trap 3 microns particles or larger with a 95% efficiency in diagnostic and research laboratories. These hoods are specifically designed for laboratory works on dangerous and respiratory viruses [6]. If the laboratory is not equipped with a ventilation system and a suitable hood, transporting the sample to a reference laboratory instead of using several non-standard laboratories is recommended. For disinfection of hospital interior surfaces, the most effective disinfectants for inactivating viruses include alcohol-based disinfectants (ethanol), chlorine, and aldehydes. Savlon is a well-established antiseptic in Iran. This brand is actually a combination of two disinfectants of Chlorhexidine and Cetrimide. Sovlon is used in rapid disinfection of medical and surgical instruments, as well as surgeons' hand washing and wound cleaning. Its solution (1%) is also very suitable for disinfecting wounds and washing hand and body skin. It is a strong bactericidal, but has low effect on viruses. Two disinfectants that are effective on viruses include sodium hypochlorite and ethanol, which their minimum concentration and contact time should be considered to disable the virus. In a recent study on the SARS-Cov-2 virus, it was reported that the minimum concentration of sodium hypochlorite required to deactivate the virus was 0.21% with a contact time of 1 minute. Hydrogen peroxide is also an effective detergent with a minimal concentration of 0.5% and a 1-minute contact time for inactivation of the new coronavirus [7]. Ethanol or ethyl alcohol in the range of 78-95% requires a minimum contact time of 30-60 sec to deactivate coronavirus types including SARS-CoV and MERS-CoV. However, a risk assessment is required for monitoring all hospital units and identifying critical points that have the potential to spread the infection to personnel, and planning and performing measures according to the WHO guidelines is necessary to reduce the risk of spreading the disease [4, 8, 9]. Considering the importance of prevention in the medical staff, it is recommended to educate these personnel by educational programs, especially hospital health experts.

Since the use of antibiotics and the release of their residuals to the environment have extensively been growing, it is expected to see mutagenated and resistant bacteria, which are a serious threat to the human health and natural ecosystems. In this study, a novel electrochemical advanced oxidation process by means of the β-PbO2 was employed in order to decompose ciprofloxacin.

This experimental cross-sectional study was performed by a pilot-scale reactor. In order to prepare the β-PbO2 electrode, the electrochemical method was applied and SEM and XRD analyses were used to survey the morphology of the electrode’s surface. Operating parameters of pH, current density (CD), temperature, and antibiotics content were optimized. Moreover, COD removal and electrical energy consumption were studied.

The findings illustrated that the parameters and the formation of the stable layer of β-PbO2 had a basic role in ciprofloxacin destruction and the maximum removal efficiency happened under optimum conditions as follows: CD 40 mA/cm2, pH 3 and contact time 90 min. Additionaly, the antibiotic was treated better than COD and energy consumption was 38 kWh/m3 in these conditions. Also, a lower CD can be utilized for ciprofloxacin degradation, which this makes the electrode more stable in longer contact times.

This employed method in this present study could remove the antibiotic better than conventional processes. Generally, this method has high removal efficiency in ciprofloxacin destruction with minimum investments

Polyvinyl acetate (PVAc) is a type of thermoplastic resin generated by a polymerization of vinyl acetate. Effluent of this polymer is highly rich with chemical oxygen demand (COD) and total solids (TS). Due to lack of studies on the above problem, the current study aimed at obtaining a sufficient method for the effluent pre-treatment. In fact, the study discussed PVAC effluent treatment by electrocoagulation (EC) and electroflotation processes.The study considered the effect of various operating parameters such as pH and current density, initial concentration of pollutant, inter-electrode distance, electrolysis times, and types of electrode materials (iron and aluminum); COD and TS removal efficiency and optimal values of operational parameters were calculated. In the study, COD and TS reduction rates in the optimized conditions in batch flow reactor were 83% and 78%, and 80% and 72% for Fe and Al electrodes, respectively. Optimized conditions were taken as 24 mA cm -2, 20 g/L PVAC, and neutral pH in 20 minutes for Al-Al electrodes and 15 minutes for Fe-Fe electrodes, 1 cm distance between electrodes with parallel-type monopole of connection modes. According to the results, electrochemical process with batch flow tends to be a suitable pre-treatment process that is inexpensive, easily operated, and highly sufficient for effluent treatment, which contains polyvinyl acetate.

Tetrachloroethylene (TCE) is a chlorinated aliphatic hydrocarbon, used in many industries. Effective and efficient treatment of industrial wastewater, containing TCE, is one of the environmental requirements. The purpose of this study was to determine the role of alkaline environments in TCE removal rate from aqueous solutions, using copper-doped pumice. This experimental study was performed, using granulated pumice stones with a mesh 4 (8.4 mm) in alkaline conditions; the samples were coated with copper. Copper-doped pumice was prepared as a bed at doses of 1, 2, and 3 g/L; the study was performed at pH ranges of 3, 7, and 11. Based on the results, copper-doped pumice showed good efficacy in TCE removal; in addition, its performance increased in alkaline conditions. Therefore, use of this stone for the treatment of wastewater, containing TCE, is effective due to its availability and low cost. Besides, it can be considered a good option, given its high efficiency in the absorption process.

It is obvious that, the organic load of wastewaters produced by food industries, especially the egg processing industry, is very high, therefore, it is necessary to use a cost efficient method with high efficiency for the treatment of this kinds of wastewater. Thus, the aim of this study was to investigate the effect of the electro-coagulation process for the treatment of the wastewater of egg processing industries.
This experimental study was carried out on the wastewater of this industry in a batch system during three seasons (summer, autumn and winter) in 2015. Without pH adjustment, the effect of operating parameters including current density, retention time and electrode type, on COD reduction was investigated. Also, the technical and economic assessment in terms of energy and electrode consumption was studied.
The results showed that, COD removal efficiency increased with increasing current density as well as increasing operating time; naturally, it is necessary to determine the optimum points in order to reduce operating costs including energy and electrode consumption. Maximum removal efficiency of COD (99%) was obtained using the aluminum electrode at contact time 10 min and current density of 7mA/cm2. Also, aluminum electrode with energy consumption of 9kwh/m3 and anode consumption of 0.5 mg/cm is more economical than iron electrode.
According to the results, in comparison to conventional methods, the treatment of the wastewater of egg processing industries using the electro-coagulation process is more effective and cost efficient.

Pentachlorophenol (PCP), which is one of the resistant phenolic compounds, has been classified in the category of EPA’s priority pollutants due to its high toxicity and carcinogenic potential. Therefore, its removal from water and wastewater is very important. Various methods have been studied for removing the compound, among which advanced oxidation processes (AOPs) have attracted much attention because of ease of application and high efficiency. Thus the aim of this study was to investigate the efficiency of the UV/ZrO2/H2O2 process, as an AOP, for PCP removal from aquatic environments. The effects of several parameters such as ultraviolet (UV) exposure time, initial PCP concentration, pH, concentration of zirconium dioxide (ZrO2) nanoparticles, and H2O2 concentration were studied. Kinetics of the reaction was also detected. The concentration of the stated materials in the samples was determined using a spectrophotometer at 500 nm. The results showed that the highest efficiency (approximately 100%) was reached at optimized conditions of pH 6, contact time of 30 minutes, initial PCP concentration of 20 mg/L, the nanoparticles concentration of 0.1 g/L and H2O2 concentration of 14.7 mM/L. Also, the process followed the first order kinetics reaction. The obtained results illustrated that the UV/ZrO2/H2O2 process has a high ability in removing PCP.

In the current study, the life cycle assessment (LCA) method was used to expect the emissions of different environmental pollutants through qualitative and quantitative analyses of solid wastes of Qazvin city in different final disposal methods. Therefore, four scenarios with the following properties considering physical analysis of Qazvin’s solid wastes, the current status of solid waste management in Iran, as well as the future of solid waste management of Qazvin were described. In order to detect the quantity of the solid wastes, the volume-weighted analysis was used and random sampling method was used for physical analysis. Of course, regarding the method of LCA, it contains all stages from solid wastes generation to its disposal. However, since the main aim of this study was final disposal stage, the emissions of pollutants of these stages were ignored. Next, considering the mixture of the solid waste, the amount of pollution stemming from each of final disposal methods from other cities having similar conditions was estimated. The findings of the study showed that weight combination of Qazvin solid wastes is entirely similar to that of other cities. Thus, the results of this study can be applied by decision makers around the country. In scenarios 1 and 2, emission of leachate containing high amounts of COD and BOD is high and also the highest content of nitrate, which can contaminate water and soil resulting in high costs for their management. In scenarios 3 and 4, the amounts of gaseous pollutants, particularly CO2, as well as nitrogen oxides are very high. In conclusion, the LCA methods can effectively contribute to the management of municipal solid wastes (MSW) to control environmental pollutants with least expenses.

Development of enormous industries has resulted in the entrance of dangerous and toxic compounds such as heavy metals into the environment polluting water bodies. Lead, which exists in most of industrial effluents, has a high contamination potential. In the present work, performance of nanofilteration (NF) membrane (NF 90) has been studied to separate lead from synthetic wastewater.
The present research was conducted experimentally in a batch reactor. All of the parameters including Pb concentration (10-90 mg/L), pressure (6-18 bar) and ionic power (50-150 mg/L of NaCl) were optimized by the one at a time in 15 times and within a fixed temperature (25± 2 °C) and pH (5.4± 0.1). Also, the removal efficiency of Pb and permeate flux were detected.
The findings showed that the removal efficiency went up dramatically when pressure was raised from 6 to 9 bar. But 1% increase was observed in efficiency with increasing pressure from 9 to 18 bar. Besides, the efficiency decreased by 5.5% with increasing initial lead concentration. It was also found that the efficiency increased in the presence of NaCl. The highest removal efficiency (over 99%) was achieved at initial lead concentration of 10 mg/L, pressure of 18 bar and NaCl concentration of 150 mg/L.
Since this technique can remove Pb, it can be applied in industrial applications. Of course, in the case of real wastewaters, operating parameters are required to be optimized.

Production and processing of raisin different areas are different based on weather conditions and their technological devices. Thus, generated wastewaters in each area are very different from another one in terms of quality and quantity. The objective of this study was to investigate the efficiency of the electrochemical process, which is an environmentally benign and simple technique, in the effluent of a raisin cleaning factory.
The wastewater from a raisin cleaning factory was treated by the electro-oxidation process in pilot-scale reactor (as batch) with an effective liquid volume of 80 ml. In order to study the amount of the performance of this process in organic matters removal, chemical oxygen demand (COD) of the samples were measured before and after every run. Moreover, the effects of parameters pH, current density, and reaction time were studied and consumed electrical power was calculated.
It was found that 86% of COD was removed at the following conditions: pH 3, current density 40 mA/cm2 and reaction time 360 min and the efficiency went up with increasing both time and current density. Further, at optimum conditions, the amount of electrical energy consumption was 5.4 kW/h COD.
Considering high loading rate of the wastewater in this study, this system can be applied as a pretreatment step despite having high efficiency and the effluent from this process requires further treatment to meet environmental standards.

Nowadays, owing to industrial activities heavy metals alongside chemical and physical pollutants are discharged to the environment resulting in extensive pollution of water bodies. Thus, simultaneous reduction of hexa-valent chromium and nitrate using granular zero-valent magnesium was studied. The current experimental study was conducted in 250 ml erlens on a shaker as bench scale. The effects of pH, zero-valent magnesium concentration, initial concentration of chromium and nitrate, contact time, temperature and reduction-oxidation potential were studied. In order to measure chromium and nitrate, the methods of colorimetric and cadmium reduction were applied by using direct reading. The efficiency of hexa-valent chromium and nitrate removal increased with increasing magnesium concentration, initial concentration of pollutants, contact time and temperature, while it decreased when there was an increase in pH value. The highest efficiency was reached in the following conditions: pH=3, magnesium concentration=0.7 g/L, and initial chromium concentration=100 mg/L. The findings showed that the two pollutants interface each other leading to a decrease in the efficiency as the reduction of hexa-valent chromium and nitrate decreased to, respectively, 93.8 and 72% at the optimum conditions and 81 and 46% at the separate simultaneous reduction. Considering there are various pollutants in industrial wastewaters, the results of this study illustrated that zero-valent magnesium can be applied to remove several pollutants simultaneously.

The discharge of wastewaters containing an untreated dye results in aesthetic problems and an increase in gases solubility, which causes light transmission inhibition into water bodies. In spite of advantages of physicochemical and biological methods, these processes produce huge amounts of sludge, toxic by-products and require several oxidant chemicals. By contrast, electrochemical processes because of their high versatility, high efficiency and eco-friendly properties are more acceptable. In the present study, the removal of azo dye Acid Red 18 and chemical oxygen demand (COD) from synthetic wastewater by monopolar (EC) process was investigated and key parameters such as operating time, current density (CD), initial pH and energy, and electrode consumption were optimized. It was found that the process had a very good efficiency in the removal of both COD and color; for the iron electrode, the maximum amounts of color and COD removal were 99.5% and 59.0%, respectively. An operating time of 45 min, pH of 7 and CD of 1.2 mA/cm2 was selected as the optimized condition. The optimization of variables is extremely crucial as it results in a decrease in costs, energy and electrode consumption. Overall, the iron electrode used less energy than the aluminum electrode and was more acceptable for use in this process due to economical reasons. The findings of UV/vis spectra illustrated that the structures of this dye were removed by the process. In comparison with traditional methods such as aerobic and anaerobic systems, the EC process is a suitable alternative for the treatment of wastewaters containing dye pollutants.

Electrochemical methods, as one of the advanced oxidation processes (AOPs), have recently been applied to remove different contaminants from water and wastewater. This study compares the performance of anodic oxidation (AO) and electro-Fenton (EF) methods on waste sludge treatment. This experimental study was performed on real sludge and the effect of operating parameters such as solution pH, operating time, current density, supporting electrolyte and hydrogen peroxide concentration were investigated in a batch reactor. For determination of oxidation and treatability of the sludge, chemical oxygen demand (COD) and total coliform (TC) removal were examined. Pb/PbO2 and iron electrodes respectively for AO and EF were applied. Experimental data indicated for both AO and EF as the operating time and current density increased, COD removal increased. pH=4.0 and 3.0 and current density=1.75 and 2 A respectively for AO and EF and the concentration = 57.2 mMol of hydrogen peroxide for EF were measured as the optimum amounts of these variables. The removal efficiency of COD in AO and EF process was 76% and 72%, respectively. Of course, the efficiency of EF in TC removal was better and the percentage of TC removal in 60 min for AO and EF was 99.0% and 99.9%, respectively. The amounts of consumed electrical energy for AO and EF were 8.6 and 28.0 kWh kg-1 COD, respectively. AO was more effective in treatment and mineralization of waste sludge and TC removal than EF in terms of environmental economical features.