مجله آب و فاضلاب
پیاپی 141 (مهر و آبان 1401)

Disposal of dyes containing dyes from related industries has caused global concern. Therefore, removing dyes from aqueous solution is very important and necessary. In this work, a novel magnetic glycodendrimer is introduced as effective adsorbent for malachite green adsorption. Firstly, magnetic graphene oxide was prepared by co-precipitation method and then modified with ethylenediamine to generate amine group on the surface which was further reacted with mercaptoacetic acid to provide polymerizable MGO nanosheets. Thereafter, Allylamine was grafted onto nanosheets and subsequently, reacted with methacrylate in a Michael type reaction to generate methyl ester groups. Finally, amidation of the terminal methyl ester groups with chitosan resulted in the formation of glycodendrimer. The properties of the synthesized adsorbent were investigated using XRD, FTIR, BET, FESEM and TEM. The results showed that pH=5, temperature of 40 °C, initial concentration of 600 mg/mL and contact time of 10 min as optimal values for removing malachite green dye with nanosorbent (MGD) were obtained. The maximum adsorption capacity of green malachite was 452.97 μg/mg. The high correlation coefficient (R2=0.9947) for the Freundlich model confirms that the Freundlich model is suitable for fitting laboratory data. According to the compliance model, the heat absorption for malachite green is B=8.1447 j/mol and indicates that the process of dye adsorption with nanosorbent is physical. According to the results of fitting the kinetic models of dye adsorption kinetics by nanosorbent shows that Hu and McKay model with higher correlation coefficient (R2=0.994) than other models is more consistent with experimental data. Due to the fact that a large decrease in dye removal is not observed in 10 consecutive recovery cycles and therefore nanosorbent has a high stability and can be used several times.

Plenty of methods have been introduced to treat the consumed water where the advantages and disadvantages of each method define their applications. Advanced oxidation processes have become a scientific trend due to high removal efficiency. As one of the AOP methods, heterogeneous Fenton method has received plenty of interest because of its high operational capability. In this study, cellulose/CuBDC/Fe3O4 nanocomposite was utilized as heterogeneous Fenton catalyst to remove Direct Blue 71 toxic dye from aqueous media. The catalyst was synthesized as granulated beads to eliminate the operational limitations of utilizing powdered catalysts. The catalysts were characterized by SEM, EDX, FTIR and XRD analysis to validate the successful synthesis procedure. The effects of each component of the nanocomposite on the removal efficiency were investigated. The effective operation of independent parameters such as the initial dye concentration, H2O2 concentration and catalyst dosage were modeled and optimized by RSM design of experiments method. At the optimum point, the removal efficiency of 86.93% was achieved. In addition, the COD of the wastewater was decreased by 73.52%, which demonstrated the high potential of granulated cellulose/CuBDC/Fe3O4 nanocomposite in decomposing organic matter to H2O, CO2, NO2 and SO2. The prepared granulated catalysts retain their removal characteristics over 8-cycle operation.

Groundwater is the most important source of fresh water supply in arid and semi-arid regions around the world, so it is necessary to maintain it through proper management in the use of these resources. Predicting areas of the aquifer that are most likely to be vulnerable is a powerful tool for optimally managing groundwater resources. Using numerical models, it is possible to predict how the aquifer reacts to the harvesting and feeding of the aquifer, with the prevailing trend or different management scenarios. The purpose of this study is to evaluate the effect of current management plans of the aquifer and the catchment area of the Jajroud River on changes in aquifer water levels and changes in nitrate ion concentration in the Varamin Plain, using numerical modeling. In this study, the effect of aquifer and catchment management plans of Jajrud River on changes in aquifer water level and changes in nitrate ion concentration in Varamin Plain, using numerical modeling. In this study, first a quantitative model was prepared in GMS software using MODFLOW code and then qualitative data were entered into the model.  MT3D code was used to run the model. The model was simulated in both stable and unstable modes. After calibrating the model, the hydrodynamic coefficients were corrected and then, using the obtained model, the quantitative and qualitative behavior of the aquifer for the coming years was predicted for two management scenarios. The resulting model showed that with the continuation of the current trend in the aquifer (first scenario), the trend of quantitative and qualitative decline of the aquifer will continue as in previous years, but in the second scenario, with reduced harvesting from wells, municipal wastewater treatment plant will be commissioned. The artificial feeding of the aquifer and the use of the effluent of the Tehran water treatment plant to irrigate the Varamin Plain will significantly reduce the water level decline. Comparison of model implementation in the first and second scenarios shows that with the implementation of planned projects, part of the quantitative problems of the aquifer, especially in the northern areas of the plain will be reduced, so that in some areas, groundwater loss calculated in the quantitative model of the first scenario (until 1420) is reduced by about 30 to 40 meters. The output maps of the qualitative model of the first scenario show that in 1420 the concentration of nitrate in a large part of the aquifer will reach over 40 mg/L, which indicates serious health threats to the region. Simulation in the second scenario shows that the implementation of artificial feeding plan and feeding the aquifer with the effluent of the wastewater treatment plant (with a concentration of 50 mg/L) will not have much effect on reducing nitrate in the aquifer. In general, the implementation of nutrition and consumption management plans in the Varamin aquifer can only lead to a reduction in the quantitative and qualitative decline of groundwater in the aquifer that does not significantly reduce the percentage of water entering the aquifer. Certainly, using the current management methods (second scenario) will not have much effect on improving the aquifer. In addition to the plan to import wastewater from the Tehran treatment plant to the Varamin Plain, the plain should continue to be fed from the Jajrud River as a suitable natural feeding source.

Wastewaters containing heavy metals produced by industries has detrimental effects on the environment. One of the effective methods for removal of heavy metals is the use of adsorption method by nanoparticles. The aim of this study was to remove zinc and nickel elements from effluents of Tarom industrial Town of Zanjan using modified multi-walled carbon nanotubes. In this  descriptive-analytical study, effect of effective parameters such as contact time, adsorbent content, pH, temperature and concentration of metal ions on the removal efficiency of metals from Ni(II) and Zn(II) from wastewater and isotherm, kinetics and thermodynamic models of adsorption process was investigated. SEM and FTIR spectrums were taken to prove nanotubes and to determine adsorbent factor groups before and after preparation, respectively. The results of study showed that the absorption of Zn and Ni metals is highly dependent on pH. Study results showed that by increasing the pH of effluent up to the range of 8, and 7 for Ni(II) and Zn(II) metals, respectively, the removal percentage of metal ions increased and then decreased. By increasing in the adsorbent amount and contact time, the removal percentage of metal ions increased and by increasing the reaction temperature and concentration of metal ions in the effluent, the removal percentage of metal ions decreased. So that, the highest removal percentage of Ni(II) and Zn(II) ions was obtained in adsorbent value of 2 mg/L, contact time of 120 min, concentration of 100 mg/L and temperature of 15 °C. The results also showed that the adsorption of Ni(II) and Zn(II) metals from effluent follows Langmir isotherm absorption model and the adsorption kinetics is adapted to the second-order pseudo-reaction (R2>0.98), this mechanism is controlled by adsorption. Also, based on the obtained results, with increasing temperature, the free energy of Gibbs system standard decreased, which indicates the adsorption process is done spontaneously. The maximum adsorption capacity of nickel and zinc metals was 43 and 54 mg/g, respectively. According to the results, it is concluded that modified multi-walled carbon nanotubes have good ability to remove nickel and zinc from effluents and can be used in wastewater treatment containing heavy metals.

Pharmaceutical industries, due to the production of a wide range of drugs, have pharmaceutical effluents and wastewater in various types of synthetic, chemical, biological drugs, etc. The entry of these substances into the cycle of the environment and human life is extremely harmful and carries serious risks. Therefore, pharmaceutical wastewater treatment is of great importance in industry. There are various methods on an industrial scale to remove contaminants and pharmaceutical effluents, among them, electrochemical and oxidation-based methods are very suitable for industrial and medical applications due to technical-economic justification. In this study, the removal of contaminants in drug effluents was investigated using the oxidation process. In order to evaluate and determine the characteristics of high-consumption drugs (aspirin, atorvastatin, metformin, metronidazole, and ibuprofen), using a potentiostat device with a three-electrode cell, a cyclic voltammetric diagram with a 100 mV/s scanning rate was performed until the initial and peak conditions were reached. Oxidation of drug samples were evaluated. Then, using the chronoamperometry process (constant potential application), the drugs were subjected to an electrochemical oxidation process (using three-electrode cells), and the drug removal process was performed for insoluble and liquid samples. At the end of the chronoamperometry method (drug removal), the samples were again subjected to cyclic voltammetry test, and the level below the oxidation peaks of the sample was calculated and compared with the level below the initial peak, thus determining the removal efficiency of the sample (removal rate). The results indicate that this method has shown about 70% efficiency for removing selected drugs with a high removal efficiency and for the atorvastatin sample specifically, it was about 100%. It should be noted that the oxidation time of each drug varies according to the type of drug and the concentration of the drug under study. About 100 to 500 seconds seems to be enough to remove the drug in most cases. The oxidation potential of selected drugs is in the range of -0.8 V. Therefore, according to the results obtained, this method has high and sufficient accuracy (RSD about 2%).

Due to strong oxidizing properties, titanium dioxide or titania nanoparticles are widely used in the water and wastewater treatment industry to remove or reduce various contaminants. The extraordinary properties of titania have led to the neglect of its side effects on the environment, especially on the aquatic ecosystems. In this study, different concentrations of titania nanoparticles were used over a period of 96 hours in lab scale to evaluate their impact on the heavy metals distribution in an aqueous media. The sediment samples of Anzali wetland contaminated with heavy metals were applied in all experiments. The results revealed that arsenic (As) was strongly affected by titania nanoparticles and its exchangeable bonds were desorbed from the sediment. Subsequently, 50 ppb titania led to concentration of As in the water column, which increased from 0 to 9 ppb. In addition to As, nickel (Ni) was desorbed from sediment through the separation of its organic bonds. On the other hand, 50 ppb titania reduced the concentrations of manganese (Mn), copper (Cu) and zinc (Zn) in the water column from 42, 32 and 29 ppb to 17.7, 2.87 and 20.9 ppb, respectively. According to the chemical extraction analysis, heavy metals adsorption in the sediment was mainly in the form of exchangeable and sulfide bonds. However, lead (Pb) and cobalt (Co) were not affected by titania and exhibited a conservative behavior.

The prevalence of COVID-19 causes many environmental problems, including increased medical waste and household waste, increased detergent consumption, reduced waste recycling and pollution of surface and groundwater resources through the entry of contaminated wastewater and leachate transfer, as well as increasing demand and water consumption in the household sector. COVID-19 virus RNA is found in feces, urine and sewage in different parts of the world, and in fact, hospital sewage, especially infectious disease units, contains the pandemic COVID-19 virus. Therefore, the study of this virus in wastewater is necessary to protect the quality of water resources. This study is based on a review of more than 200 published scientific literatures (articles, books, reports, valid scientific sites, etc.) in relation to the coronavirus. For this purpose, keywords such as "coronavirus contamination of water and wastewater resources", "environmental effects of coronavirus", "effects of physico-chemical indicators of wastewater on coronavirus survival" and "number of infected and deaths due to Coronavirus" have been used and downloaded through electronic tools from Springer, PubMed, ISI Web of Knowledge and Google Scholar databases. In addition, data on the amount of water consumption in different parts (residential and non-residential) of Mashhad city, and the concentration of physicochemical parameters (such as temperature (T), pH, suspended solids, total solids (Ammonia, etc.) of wastewater, related to Khin Arab and Parkandabad treatment plants in Mashhad, has been obtained from Mashhad water and sewerage company. The required diagrams were drawn in Excel software, and the environmental impact and the contamination of water resources with COVID-19 and variations in physico-chemical parameters of wastewater affecting the survival of COVID-19 in wastewater were examined and analyzed. The global prevalence of Coronavirus has many negative impacts on the environment and on water and wastewater resources and caused increased water consumption (in residential sector) and wastewater production. By January 2022, worldwide, Iran and Khorasan Razavi province levels, more than 312 million, 6 million and 75 thousand people, respectively, were suffering from coronavirus outbreak, and more than 5.5 million, 133 thousand and 11 thousand people died. In general, the effect of concentration of wastewater’s physico-chemical indicators on the concentration and survival of COVID-19 has been proven in the world (especially in the South African coazolonatal treatment plant). The results of this study show that the parameters of each wastewater and survival and concentration of COVID-19 depends on the characteristics of the wastewater source, which should be given special attention in research on the epidemiology of wastewater. The variations in the concentration of physico-chemical indicators of Mashhad treatment plants’ (Parkandabad and Khin Arab) wastewater shows increase in concentration of some wastewater indicators. This can be due to the high input of organic and chemical substances and of solids (suspended, soluble and volatile) such as: detergents and disinfectants and pharmaceuticals, hospital and medical waste were attributed to wastewater after the outbreak of COVID-19. The outbreak of Coronavirus in the world has not only caused the death and infection of many people, but it has also caused increasing and decreasing in water consumption in the residential and non-residential sectors. The concentrations of some wastewater’s physico-chemical indicators (such as pH, TS and ammonia) effects on the concentration, survival and shelf life of Coronavirus in wastewater. Therefore, by determining the concentrations of these indicators in wastewater at different times and monitoring its variations, it is possible to determine the survival of COVID-19 virus in wastewater, the rate of infection and the contaminated areas from the virus, and also to be able to control COVID-19 and to manage the pollution and infection.

One of the major challenges in arid regions such as Iran is the supply of water with appropriate quantity and quality. Drought, disputes over water resources, and providing good quality and quantity water for drinking, agriculture, and industrial sector, have forced governments to use desalination technology or transfer water among watersheds, Water desalination is one of the solutions to providing drinking water in Central Iran and coastal areas. Bajestan plain is no exception and has been using this method for about 16 years to provide drinking water and health for residents. Investors have recently been encouraged to build mineral water plants in arid areas; While the socio-economic and its environmental consequences are not yet clear. The results of this study showed that to supply fresh water from desert saline water with EC about 7500 (µs/cm) and reverse osmosis method with a production volume of 1000 (m3/yr), the price per liter of water is equivalent to 45.067 IRR. In this process, around 500 m³ of saline water and more than 6 tons of salt will be produced, too. This amount of salt will increase the salinity of the lands around the pistachio fields and orchards by 2 to 3 times and decrease the yields by more than 60%. Results showed if the bottles are not recovered, more than 18 tons of polyethylene will be produced. The economic evaluation shows that the value of the Net Present Value Index is negative and Internal Rate of Return is not acceptable, and the B/C is 0.46, which indicates that it is not economical to implement. Implementation of this plan in other arid regions with these conditions will have similar results.

The large volume of consumed water and pigments in the textile industry subsequently produces hazardous wastewater, which potentially may cause serious environmental problems. On the other hand, due to water stress in Iran, the need for further treatment of this wastewater is more urgent. In recent years, electrochemical processes have been considered as an efficient process. The lack of information to build large-scale electrical coagulation units has led to the deficiency of extensive application of this method in industrial units. In this paper, the removal of color and COD in the wastewater of a textile factory in Tehran has been studied in order to determine the efficiency of the electrocoagulation process and to find optimal operation parameters. Optimum distance between the electrodes (4 cm), optimum electrical potential (40 V) and electrolyte concentration (4 mgNaCl/L) are the main achievement of this research. The treatment efficiency achieved in this research is 69% for COD and 96% for color removal.

One of the most pressing challenges confronting modern civilization is the lack of enough clean water supplies. Membrane technology has emerged as a key technology for water treatment, including fresh water, salt water, and municipal or industrial wastewater treatment, owing to its energy savings, high performance efficiency, and cost-effectiveness. However, membrane fouling, resulting from a non-specific interaction between the membrane surface and fouling agents, significantly hinders the efficient utilization of membrane technology. The fabrication of antifouling membranes is a fundamental approach to dealing with fouling issues caused by various types of fouling agents. Significant progress has been made in membrane preparation techniques and modification strategies, notably in microfiltration membranes, in recent years. While outlining the key strategies for modifying antifouling microfiltration membranes, the present review highlights recent achievements in the mentioned field, which provides more details related to the fabrication and preparation techniques and enhances performance parameters of these membranes. Microfiltration nanocomposite membranes modified by blending method can be considered an emerging technology capable of converting laboratory/pilot scale to a reliable commercial technology due to their high performance efficiency and good antifouling properties among all modification methods covered in this study. While using modification techniques (blending, surface modification, interfacial polymerization, sol-gel, and electrospinning) to better manage fouling in microfiltration membranes has certain benefits in terms of boosting performance, it also has drawbacks. Therefore, further optimization of modifying methods with the aim of commercializing modified microfiltration membranes is essential.