جستجوی مقالات مرتبط با کلیدواژه « تصفیه آب » در نشریات گروه « پزشکی »

The purpose of this study was to investigate the effect of using tubular settlers on the energy required for backwashing filters and the frequency of backwashing.

In this experimental study, two accelerator clarifiers connected to the raw water transfer channel No. 1 of the Isfahan Water Treatment Plant (WPT), Iran, were equipped with approximately 350 tubular settlers at an installation angle of 60 degrees.

The results of sampling the outlets showed that the average concentration of suspended solids in the clarifiers with tubular settlers was 3.20 ± 16.00 mg/l, while in clarifiers without tubular settlers, it was 4.41 ± 20.00 mg/l. The average removal efficiency of suspended solids in clarifiers equipped with tubular settlers was 64.86 ± 34.00%, compared to 52.10 ± 46.00% in other clarifiers. Additionally, the number of backwashing cycles of filters decreased by 25%, and energy consumption was reduced by 50%-60%.

The use of tube settlers to improve the quality of water entering filters reduces the number of backwashing cycles per day and ultimately saves energy for backwashing filters, which is very effective.

Pharmaceuticals, especially antibiotics, are new contaminants that have created a major environmental concern because of their cumulative nature, adverse effects, and drug resistance. Their existence in domestic wastewater will pollute water resources. This study aimed to determine the performance of US/UV/SO40‒ processes in the removal of Amoxicillin (AMX).

The current experimental study used ultrasonic waves (US), ultraviolet rays (UV), and sulfate radicals (SO40‒). To detect the effect of variables, including contact time (0-120 min), the antibiotic concentration (5-50 mg/l), pH (3-9), persulfate concentration (1-7 mM), and the input power (550 W), the reactor has been sampled in different intervals, and the residue concentration was detected using a spectrophotometer in 294 nm length wave.

The results showed that the separate use of US and UV had no high operation with the best removal percentages of 33.3% and 13.29%, respectively. Simultaneous use of US/UV/SO40‒ showed a more high reduction in AMX concentration and the best removal percentage was 94.12% that took place in pH=6, the antibiotic concentration of 5 mg/L, persulfate concentration of 5 mM, and contact time of 120 min.

The result showed that the US/UV/SO40‒ process can be used as an operational process to remove the AMX from an aqueous environment.

Nanotechnology is a field of applied knowledge. The use of nanotechnology and silver nanoparticles has been studied in recent years to control bacterial diseases. This study aimed to investigate the antibacterial effect of ceramic filter pads containing silver nanoparticles in the control of E. coli.

The present work was an experimental study. Silver nanoparticles were synthesized by dissolving silver nitrate (AgNO3) in ethanol and reducing silver in an alcoholic medium. Characteristics of filters were evaluated using BET, SEM, XRF, and XRD tests. Ethical considerations were observed in all stages of the study.

The results showed that the removal efficiency of E. coliwas 36.2-66.7% by conventional filters and reached up 99-100% by ceramic filters coated with silver nanoparticles

The results of this study showed that ceramic filter media containing silver nanoparticles have considerable antimicrobial effects. By generalizing the results of this study, these ceramicfilter media can be used in the treatment and filtration of unsafe water and thus control of pathogens in drinking water.

Nitrate is one of the most important pollutants in surface and groundwater. The present study aimed to evaluate the effect of different parameters on the performance of the electrical coagulation process in the removal of nitrate from contaminated water.

This study was conducted based on an experimental design and the statistical community was urban water. A cylindrical batch reactor with aluminum and zinc electrodes (monopolar arrangement) was used to remove 100 mg/L nitrates. The experiments were performed three times in direct and alternating currents using standard methods. Factors of pH, contact time, and weight of electrodes were evaluated, and the results were reported in tables and graphs.

Nitrate removal efficiency (87.4%) was higher in direct current, as compared to that in alternating current (39.1%). The highest nitrate removal efficiency of 87.4% was obtained in direct current, in comparison with 61% for alternating current. As the contact time increased, the pH of the solution increased in two currents, from 7 to 11.21 and 8.47, respectively. Total dissolved solids (TDS) at optimal conditions in alternating and direct current were 79 and 126 mg/L, respectively. After 30 min of settling, the produced sludge was measured as 17.66 and 280 mL/L in direct and alternating current, respectively. The weight of the anode electrode had the greatest decrease in direct current.

The results of this study pointed out that the process of electrical coagulation could reduce the concentration of nitrate to less than the standard. Nitrate removal with the direct current was performed with less energy consumption and cost than alternating current. As a result, the use of optimal conditions increases the process efficiency in the electrochemical removal of nitrate.

Chlorpyrifos (CPF), an organophosphate pesticide, has been widely used in the agricultural industry and may cause environmental damage. The present study aimed to evaluate the potential application of Fe(VI) and Fe(VI)/PMS processes for oxidation of CPF in water after pretreatment with ferric chloride coagulant.

This study was performed in two phases including coagulation and flocculation process and advanced oxidation process (AOP). In the first phase, the coagulation process was performed for turbidity removal by ferric chloride (FeCl3). In this phase, using a central composite design (CCD) with R software, the combined effect of four variables including initial turbidity, initial pH, coagulant dose and contact time was investigated. The supernatant from this process was transferred to the next phase for further analysis. In the AOP phase, the effect of Fe(VI) and Fe(VI)/PMS oxidants were investigated separately.

In the first phase (coagulation and flocculation), FeCl3 showed the highest efficiency (95.79%) at alkaline pH (pH=8). In the next phase (AOP), the results showed that the degradation efficiency of Fe(VI)/PMS process was higher compared to sole Fe(VI) process at all pHs. Also, by examining the reaction kinetics, it was found that after the coagulation process by FeCl3, the removal rate in the Fe(VI)/PMS process is 1.5 times higher than the Fe(VI) process.

Due to the high removal efficiency and higher degradation rate of Fe(VI)/PMS process, this technique can be used as a relatively effective method in removing chlorpyrifos from aqueous solution.

With increasing water pollution, serious water shortages and increased pressure to save water, recycling and reuse of water has attracted more attention in various industries. Removal of silica from cooling water is essential for recycling and reuse of water. The aim of this study was to remove silica from water using magnesium oxide nanoparticles (MgO) synthesized by chemical deposition method.

Synthetic nanoparticles were successfully determined using field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR) and X-ray diffraction (XRD). To determine the optimal adsorption conditions the batch system, the effect of important parameters such as pH (2-8), contact time (0-150 min), initial concentration of silica solution (50-1000 mg/L), adsorbent amount (0.01-0.14 g) and temperature (25-60 ˚C) were studied.

Under optimal conditions, an almost removal of 200 mg/L silica solution was achieved in 60 min reaction time. Equilibrium data were analyzed using the Langmuir and Freundlich isotherms. The adsorption process can be well described by the Langmuir model, and the maximum adsorption capacity was calculated as 75.76 mg/g. Synthetic data were analyzed using pseudo-first-order and pseudo-second-order equations. The pseudo-second-order model showed good agreement with the obtained data (R2 = 0.9949).

Due to the high potential of magnesium oxide nanoparticles in silica removal, it can be a good candidate for the removal of silica and industrial wastewater treatment.

Azo dyes are considered a potential risk to the environment due to their widespread use in various industries as well as their toxicity. Therefore, effective removal of this pollutant from the environment seems to be necessary. The aim of this study was to investigate the process of heterogeneous Fenton with zero-valent iron particles in the removal of an azo dye.

The present experimental study was performed in 2019 in a laboratory scale in a batch reactor. In this study, the efficiency of heterogeneous Fenton-like process on azo dye removal was evaluated under different operating conditions (pH, contact time, hydrogen peroxide concentration, and dye concentration). The concentration of the studied dye was measured using a spectrophotometer.

The results of this study showed that the heterogeneous Fenton-like process in the presence of zero-valent iron particles can remove 97.3% of azo dye with the intital concentration of 50 mg/L at an initial pH of 6, hydrogen peroxide concentration of 6 mmol/L, and Fe particles dose of 0.5 g/L within 10 min of contact time.

In this study, it was found that azo dye can be effectively removed from the aqueous solution by heterogeneous Fenton method. Therefore, applictaion of zero-valent iron particles in the Fenton process is recommended for the effective removal of organic pollutants, especially dyes, from the aquatic environment.

Nitrate, due to its high solubility in water, causes pollution of groundwater resources, poses a serious threat to human health and causes eutrophication of water resources. The aim of this study was to optimize the use of modified pumice in the removal of nitrate from water.

This experimental study was performed in 2020 on laboratory scale. The experiments were designed using the Box-Benken method. The studied variables included pH (2-4), initial nitrate concentration (50-100 mg/L), contact time (15-45 min) and pumice dose (0.5 - 1.5 gr/L) at three levels. Thus, a total of 29 experiments were designed and performed. Experimental design and statistical analysis were performed using Design Expert 7.0 software. All examinations were performed according to the instructions provided in the latest edition of the Standard Methods for the Examinations of Water and Wastewater.

The results showed that the quadratic polynomial equation fitted well with the experimental data. Also, the liner effects of all four variables (including pH, initial nitrate concentration, contact time and modified pumice dose), as well as interactions effects and quadratic effects of each variable on the nitrate removal efficiency from water were significant (P-Value <0.05). The results of numerical optimization showed that the optinal conditions included pH of 2.01, initial nitrate concentration of 70.45 mg/L, reaction time of 44.98 min, and modified pumice dose of 1.21 gr/L. Under these conditions, nitrate removal efficiency, model desirability, and predicted R2 were 89.66%, 100% and 0.82, respectively.

According to the results, magnesium-modified pumice can be applied to remove nitrate from water. However, it should be mentioned that the pH of the water, after purification, must be modified with a suitable alkaline substance.

Industrial wastewater treatment has always been difficult and costly due to the presence of different and high concentrated pollutants. The use of constructed wetlands is economical due to the need to use no external energy sources and materials and equipment to reduce pollutants. The aim of this study was to determine the efficiency of horizontal and vertical subsurface wetlands in the removal of pollutants from the wastewater of the Mourchekhort Industrial Estate and its comparison with performance of the conventional coagulation-flocculation-filtration unit of reuse process.

Two horizontal and vertical wetlands in pilot scale and two control (no plant) reactors were operated for eight months. Removal efficiency of TSS, COD, turbidity, phosphorous and nitrogen compounds and index bacteria were evaluated. Horizontal wetlands with dimensions of 0.8 × 0.65 × 2 m and floor slope of 1% were considered. HRT equal to 6 days and incoming sewage flow rate set to 0.2 m3/d. Vertical subsurface reed had dimensions of 0.4 × 0.60 × 2 m and floor slope was equal to 1%. The control pilot (no plant) was designed exactly the same as the horizontal and vertical tests. The results were compared with coagulation-flocculation-filtration process.

The efficiency of vertical wetland in removal of TSS, COD, turbidity, phosphorus and nitrogen compounds and index bacteria were: 58.1, 62.4, 73.4, 20.41, 21.34, 40.51%; for horizontal wetland 57, 52.59, 70.3, 22.41, 18.22, 39.08%; and for conventional treatment process 85.34, 69.7, 81.55, 69.23, 73.95 and 78.2%, respectively.

Although vertical wetland was more efficient than horizontal one for most of the operation parameters, both of these wetlands were less efficient than conventional coagulation-flocculation-filtration unit of reuse process. Although operating costs of wetlands are low, these systems alone cannot be considered as a substitute for the conventional process because of their low performance for the purpose of polishing.

The importance of water and disease transmission has been known for a long time. One of the necessities of human life, both in times of peace and in times of crisis, is to drink "safe water". Drinking healthy, disease-free water plays an important role in preventing water-borne diseases such as acute and chronic diarrhea. Water-borne pathogens are abundant and include bacteria, viruses, protozoa, and parasitic worms.Adequate water supply and water purification in emergency situations and control and monitoring of water quality have particular importance. The United Nations recommends that each person needs 20-50 liters of healthy freshwater per day to meet basic human needs such as drinking, cooking, and cleaning, of which 2-4 liters per day is sufficient for drinking and should be provided from the best quality water sources. The minimum amount of drinking water consumption on the first day after the occurrence of a catastrophe to survive in a mild climate and mountain conditions is one liter per day and to survive in hot and dry conditions 3 liters per day.In the present review study, the practical and applied methods appropriate to the available technology for the drinking water supply of small communities have been presented.

Groundwater sources, as strategic sources of water supply, are of particular importance for human beings. Arsenic is a toxic and carcinogenic contaminant that has been reported to be widely found in groundwater sources. In recent years, adsorption property of nanoparticles has been used to remove arsenic. The present study was performed with the aim of assessing the arsenic reduction process in the aqueous environment under groundwater-like conditions using titanium dioxide (TiO2) nanoparticles (anatase).

In this experimental study, using batch experiments, the effect of changes of time, nanoparticles concentration, and pH factors, were investigated on the changes in arsenic concentration in aqueous solution. The specific surface area of the adsorbent was 200-240m2/g. Data were statistically analyzed by measures of central tendency.

In this study, more than 90% of arsenic concentration in the solution, was absorbed after about 30 minutes of exposure to anatase nanoparticles, however, it took 60 minutes to reach drinking water standard level of arsenic (10µg/L). Increasing adsorbent concentration caused an increase in arsenic adsorption. In natural pH range of groundwater, TiO2 nanoparticle can absorb near 100% of arsenic (200µg/l), but, increase in pH increased this ability. Also, adsorption of arsenic by anatase nanoparticles was more consistent with the Freundlich isotherm.

The results of the current study showed that TiO2 nanoparticles are efficient adsorbents for removal of arsenic from aqueous solutions under natural groundwater conditions.

Polycyclic aromatic hydrocarbons are hazardous contaminants in aquatic environments due to their mutagenic, cancer-causing properties which are a threat for people in the community. Therefore, it is essential to remove them from water sources to protect public health and the environment. The purpose of this study was to remove anthracene from contaminated water by magnetic dendrimer nanoparticles.Methods and Materials: In this study, magnetic nanoparticles were fabricated by dendrimer-functionalized PAMAM polymers and modified with benzaldehyde ligand on the surface. The adsorbent properties were characterized by SEM, XRD, and FTIR. Then, in a batch study, the effect of operative parameters on the adsorbent and reusability of the sorbent was studied, and residual anthracene concentration in aqueous solution was determined by spectrophotometer. The obtained data were fitted to different isotherm models and kinetic models. Ethical considerations in this study were adhered based on the Helsinki guidelines.

The results showed that anthracene removal efficiency increased with contact time up to 20 minutes and adsorbent content up to 0.6 g / L at pH 7 in the solutions. It was also found that the adsorption process follows the Langmuir isotherm and pseudo-second-order kinetic model. The highest adsorption capacity of the adsorbent with qmax=105 mg / g indicates a high adsorption capacity of the synthesized magnetite dendrimer. The reusability of the adsorbent also showed that the nanostructure could be recovered by maintaining anthracene uptake efficiency for up to 7 cycles.

Based on the obtained results, it can be concluded that the synthesized nanopolymer can be used as an efficient adsorbent with high adsorption potential and capacity for anthracene removal from aqueous media.

Coagulation, which is carried out by mixing coagulants such as alum, ferric chloride and poly aluminum chloride PAC with raw water, is one of the main processes in conventional water treatment plants. Sludge from this process contains high amounts of coagulants with high economic value. Therefore, if these coagulants are recovered, in addition to reducing the risks relate to sludge disposal, the expenses related to the supply of fresh coagulant in water or wastewater treatment plant may decrease. To access related documentation, ScienceDirect, Google scholar and other databases were searched using keywords such as “coagulant recovery”, “water residuals management”, etc. More than one hundred fifty documents were investigated based on the content validity and thematic relation. Gathered contents were classified and summarized under the titles of “recovery methods”, “repeated recoveries”, “recovery regarding economic aspect” and “advantages and disadvantages of methods”. Use of new methods such as combination of membrane and chemical processes or ion exchange membrane processes leads to the recovery of coagulants with a similar quality to the commercial ones. In case of using conventional and less costly methods such as acid digestion, quality of recovered coagulants is not comparable with those of commercial ones, which are used in water treatment. Different coagulants recovery methods were investigated to determine the reuse strategies. It is likely that using of recovered coagulants through conventional methods is in accordance with the related regulations of the wastewater treatment plants. Industrial use of novel processes for recovery of coagulants with higher quality needs precise technical and economical investigations.

Agricultural poisons are one of the most important groups of pollutants in agricultural industries that cause environmental pollution. The main objective of this research was to remove imidacloprid from contaminated water by using modified magnetic-silica core-shell nanoparticles.
This study was conducted at the laboratory scale and batch system. The physical and structural characteristics of the synthesized adsorbent were determined by scanning electron microscopy (SEM). In addition, the effects of various parameters such as pH, initial concentration of imidacloprid, adsorbent dose, and contact time were investigated in order to determine the equilibrium isotherms and adsorption kinetics. The potential of the adsorbent for removal of imidacloprid showed no significant change after four runs of the reaction.
The highest efficiency was found to be 97.85 %, achieved at the following conditions: a contact time of 67 minutes, an adsorbent dose of 0.06 g/l, an initial concentration of 15.6 mg/l and a pH of 6.5. The correlation coefficient of Langmuir isotherm (R2=0.9843) was higher than that of Freundlich (R2=0.8). Therefore, the Langmuir isotherm model is hereby introduced to be used for predicting the adsorption behavior of imidacloprid onto the nano-adsorbent from an aqueous medium. The reaction kinetics fitted well with the pseudo-second-order model.
A modified magnetic-silica core-shell nanoparticle is a cost-effective and recoverable adsorbent for efficient removal of imidacloprid from contaminated water.

The removal of microbial pollutants is important for access of water quality standard. Therefore, drinking water disinfection for pathogens removal or inactivation conducted in water treatment installations. Today, due to environmental friendly, solar radiation disinfection considered. Objective of this study was effect of certain environmental factors such as turbidity, organic matter, container kind, and initial bacteria concentrations on E. coli removal from water solution using solar radiation disinfection.
Material and In this study, the performance of E. coli removal were evaluated using different container (PET and Glass), turbidity (0, 10, 20 NTU), organic matter (0, 5, 10 mg/l), and initial E. coli concentrations (100, 200, 300 bacteria/ml) as experimental study. This study conducted at perfectly sunny days in July and August between 11 to 15 o’clock with maximum radiation intensity.
Results of this study show that both PET and Glass containers are capable to decrease of 300 E.coli per milliliter to zero at 60 min contact time. With increasing of organic matter, turbidity, and initial concentration of E. coli, bacterial removal rate from water solution decreased. Generally, solar radiation can be provide 100 % removal of E. coli in a water solution with 300 E. coli/l as initial concentration, 20 NTU of turbidity and 10 mg/l of organic matter with 60 min contact time.
The use of solar radiation technology is suitable for drinking water disinfection both at household level and at remote communities even for water with high turbidity and high organic matter concentrations.

Water treatment plays a vital role in the delivery of safe and effective hemodialysis (HD). Ensuring that water quality meets the American Association for the Advancement of Medical Instrumentation standards and recommendations (or equivalent) is necessary to reduce the incidence of chemical hazards and endotoxemia associated with the use of water for HD. This review will discuss the principles of water treatment for HD, the essential components of water purification, the recommended system monitoring and maintenance procedures, and some of the historical incidents of adverse reactions that resulted from the use of contaminated dialysis water.

Introduction and The release of chlorinated organic compounds (COCs) is accounted as a danger for public health and environment due to their harmful properties such as carcinogenicity, toxicity, and flammability. Trichlorethylene (TCE) is one of the most famous COCs, which is commonly used as a solvent for dry-cleaning and industrial degreasing and contaminates soil and groundwater. Thus, it is considered as a possible carcinogenic compound (class B2) for humans. Therefore, this study was conducted to evaluate the effect of zero-valent iron nanoparticles (nZVI) in degradation of TCE.
Iron nanoparticles were prepared through the ferric chloride revival method by sodium borohydride. The properties of nanoparticles were determined using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and vibrating sample magnetometer. In addition, the effect of pH, concentration of trichloroethylene, iron nano-particle concentration, and contact time were studied on TCE removal efficiency. Box Behnken model was used to investigate the interaction of these variables. Analysis of variance was considered as the statistical method for analysis of responses.
Results on degradation of trichloroethylene with iron nanoparticles showed that the degradation efficiency was equal to 91.23% under optimal conditions (pH=3, the nanoparticles dose of 0.63 g/l, TCE concentration of 11 mg/l, and contact time of 86 min). The results of kinetic studies revealed that TCE degradation by nZVI follows first-order kinetic model.
Based on the obtained results, we can conclude that zero-valent iron nanoparticles have a good efficiency in the degradation of TCE. On the other hand, separation of these nanoparticles is simple due to its magnetism properties, which can improve the use of these nanoparticles.
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Heavy metals owing to their health hazards and high toxicity in low concentration for human and environment have very concern and attention. Slow sand filter is one of the simple and cost-effective for removal of these pollutants. In this method, media play an important role for removal of pollutant. Therefore, the aim of this study was investigation of different media like slag, zeolite, and conventional media in slow sand filter for removal of lead and cadmium.
In this research there are three beds filter include typical filter bed, slag and zeolite that used in pilot plant for investigation of lead and cadmium removal at three concentration of 0.1T 1 and 10 ppm. Each of filters has an internal diameter of 8 cm and a height of 120 cm with Plexiglas, which have a continuous flow operation.
The removal efficiency of turbidity by three typical filter bed, slag, and zeolite with initial turbidity of 13 NTU was 46%, 77%, and 89% respectively. Removal efficiency of lead without turbidity was 70.3%, 79%, and 59.8% respectively for 0.1 ppm lead. For 1 ppm, concentration of lead removal efficiency was 51.8%, 52.7% and 52.6% respectively and for 10 ppm it was 53.4%, 57.8%, and 59.8% respectively. Cadmium removal for these media was 23.4%, 37.5%, and 59.4% respectively at 0.1 ppm cadmium. At 1 ppm of cadmium concentration, it was 37.9%, 45% and 41.3% respectively and at 10 ppm concentration of cadmium it was 68.3%, 68.6% and 67% respectively.
Slag and zeolite beds are more efficiently than the conventional sand beds in the slow sand filter, so it can be used instead of the usual sand for removing lead and cadmium from resources water.

Introduction & Water treatment leads to produce large volumes of sludges in water treatment plants which are considered as solid waste, and should be managed appropriately and logically to avoid bioenvironmental effects.
In this cross-sectional study, the required samples were taken from the sludge of Shahid Beheshti water treatment plant to assay physical and chemical characteristics during one year from summer, autumn and winter 93 until spring 94. Sampling and testing procedures were full fit according to standard methods.
The average concentration of total solids parameters (TSS), total suspended solids (TSS), and total dissolved solids (TDS) were 22346, 21350 and 1005 mg/L, respectively. Among the heavy metals, aluminum, iron, manganese and zinc have the highest concentrations with the values of 1400, 956, 588 and 100 mg per kg of dry solids, respectively. The measured concentrations for cadmium were also higher than the permissible limits for agricultural purposes and discharges into the environment. The average concentrations of nickel were more than the recommended standard for industrial, agricultural and parkland application purposes. The concentrations were also slurry higher than the dry sludge.
According to the past studies and results of this study, it could be concluded that contamination of heavy metals in sludge and slurry samples are more than dried sludge, .Therefore, if they are discharged into the environment, it is better to be disposed as dry sludges. Furthermore, because these types of waste sludges are routinely disposed in the environment, it is recommended to take the routine samples in order to measure the heavy metals and other relevant parameters contents of sludge before discharging it.

Raw water is one of the main sources of water supply in some communities. Filteration of surface water resources is a challenging point in the rainy seasons due to the highly turbidity. This study was done to evaluate the removal of turbidity in raw water using chitosan in electrocoagulation process using aluminum electrodes. In this the descriptive –analytical study, a Plexiglas electrocoagulation reactor in a lab scale to an approximate volume of 6 liter which was equipped with four aluminum electrodes having dimension of 200×20×2 mm was proposed. The effects of operating parameters including pH (5 to 9), applied voltage (10 to 30 V), the initial turbidity (100-600 NTU), initial chitosan concentration (0.5-2 mg/L) and contact time (5 to 30 min) were evaluated. Turbidity removal efficiency was over 100% (pH=7, applied voltage=30 V and initial turbidity concentration of 100NTU) in the application of electrocoagulation with chitosan but in the application of electrocoagulation without chitosan removed 87% of turbidity in the same condition. Chitosan as coagulant aid in low amount can increase turbidity removal efficiency rather than application of electrocoagulation alone.