مجله آب و فاضلاب
پیاپی 140 (امرداد و شهریور 1401)

One of the most widely used polymers in the treatment and absorption of pollutants is polyethylene terephthalate, which optimizes their consumption and protects the environment by purifying water sources. The problem with this polymer is the lack of a functional group on the surface to bind the nanoparticles. Therefore, in this study, we first functionalized the polymer with the carboxylic group by chemical synthesis, then we synthesized silver nanoparticles on them by ultrasonic method. Optimal nanoparticle synthesis conditions were obtained (pH=9 and concentration 0.2 M). Under these conditions, the average particle size was 64 nm. In the second part, modified polymer was used to remove Methyl orange dye. Optimal parameters for removal were investigated (pH=9, temperature of 35 °C and ratio of dye concentration to adsorbent of 5 μM/0.1 g). The highest percentage of paint removal under optimal conditions was 92% after 120 minutes. The antibacterial effect of PET-AgNPs polymer was observed on two types of bacteria, Staphylococcus aureus and Escherichia coli, gram-positive and gram-negative. In the second part, the gold electrode was modified with a combination of PET-AgNPs polymer and carbon nanotubes and was used to detect methyl orange dye. The linear range was 5×10-6 to 2×10-8 M and the detection limit was 7.6×10-9 M. Parameters affecting removal and isotherm and removal kinetics were investigated. The functionalized and modified polymer is well able to measure and remove the contaminant dye and, in addition, it has an antibacterial effect.

The application of hydrophilic nanoparticles to modify the surface of the membrane is one of the suitable approaches to improve the properties of thin-film composite membranes, particularly for the removal of heavy metals from aqueous environments. In this research, a thin-film polyamide nanofiltration membrane with porous polysulfone substrate was prepared by TMC and PIP interfacial polymerization technique. To modify the surface of TFC membranes and produce new TFN membranes by a nanoparticle coating method, graphene oxide nanoparticles modified with 3-aminopropyltriethoxysilane were dispersed in EDC solution as an activator of functional groups, and then were layered by coating the surface of the polyamide membrane. Physicochemical features using scanning electron microscopy, Fourier Transform Infrared, water contact angle, and hydrophilicity to assess structure, morphology as well as tests of water flux and rejection rate were evaluated to estimate the performance and efficiency of the synthesized membranes in the filtration system. The findings indicated that increasing the concentration of nanoparticles improves the hydrophilicity nanocomposite membranes compared to neat TFC membranes. Functional results and membrane filtration indicated that the amount of neat water permeability of the fabricated membranes increases with increasing concentration of graphene oxide nanoparticles from about 42 L/m2.h for TFC membrane to 95 L/m2.h for the membrane containing 0.1 weight percent of graphene oxide. This trend shows the positive effect of nanoparticles on membrane water permeability. Furthermore, the rejection of cobalt heavy metal with increasing pH from 3 to 8 for all membrane samples has an upward trend, so that TFN3 membrane has the highest rate of rejection (98%) of heavy metal compared to other membranes while the amount of flux with changing pH and increasing the concentration of nanoparticles, has a decreasing trend. So, this technique can be applied as a new and effective method for the removal of heavy metals.

The biological fouling in polymer membranes is one of the main challenges in the membrane processes. Accordingly, CuO nanomaterials with properties such as high resistance to physical, chemical, biological agents, as well as antibacterial properties can be considered as one of the effective additives in the fabrication of composite ultrafiltration membranes, and reduce biological fouling. In this study, PVDF (16wt %), PVP (1wt %), CuO nano-plates (1wt %) were used in fabrication membranes (Phase inversion method) to increase hydrophilic properties, to reduce the membrane fouling and improve the ultrafiltration membrane filteration performance. The physical and chemical characterization of CuO nano-plates (synthesized by hydrothermal method) and fabricated membranes evaluated by XRD and FTIR analysis and also FESEM and TEM were used to study the morphology of the samples. The mixture of CuO nanoparticles with the semi-crystalline polymer structure of PVDF improved the β phase in the membrane structure which improved the hydrophilic properties of the membrane feature. The results showed that the flux and rejection of CuO nanocomposite membranes were 357 and 96% LMH, respectively, and the contact angle was about 59 degrees, which increased the hydrophilic properties of the surface by 25% compared to the control sample. The recovery rate of CuO nanocomposite membrane was about 83%, which indicates the effect of antibacterial properties of these nano-plates. Finally, BSA solution and municipal wastewater were used to evaluate the performance of nanocomposite membrane in filtration and purification. PVDF/CuO composite membrane had high efficiency in disinfection and wastewater treatment; The COD of the treated effluent was less than 5 mg/L and the removal of turbidity and TSS was about 99% and no fecal coliforms were detected.

Pharmaceuticals are widely used in the treatment of diseases, and among them, antibiotics are the most widely used group of drugs. The presence of these compounds in the environment is a serious threat to global health. Common methods of removing antibiotics are photocatalytic processes, advanced oxidation, ozonation, and the use of sorbents. Adsorption processes are the most suitable option for removing drug compounds from aqueous media due to their high efficiency, simple system design, easy implementation and cost-effectiveness. The aim of this study was to use a new method to achieve a high removal rate of tetracycline antibiotics from aqueous solution, using a modified pyrolytic coke adsorbent and to optimize the adsorption process. The properties and characteristics of the adsorbents were determined by SEM, XRD, FTIR, BET and EDX analyses. At ambient temperature (25 ℃) the influence of effective factors such as adsorbent dose, solution pH, contact time and initial contaminant concentration were investigated. Based on the results, it was found that the optimal and maximum adsorption of tetracycline was occurred at pH=5, absorbent dose of 3 g/L, the initial concentration of 50 mg/L and the contact time of 90 minutes. This rate was equal to 96.32 percent. The results of FTIR analyses showed that the uptake of tetracycline by positive amine-NH groups was done at the adsorbent level. Also, the adsorption process of tetracycline by the modified adsorbent followed the Temkin adsorption isotherm model and the pseudo-second-order adsorption kinetics model.

Encouraging households to adopt residential water conservation behaviors, as an efficient strategy for sustainable water supply, has caught the attention of water demand management. However, the success of such policies depends on the voluntary acceptance of these measures by urban households. Considering the important role of psychology in explaining human behavior, the present research explored the key socio-psychological factors underlying the household adoption of WCBs and how these behaviors can be explained by expanding the theory of planned behavior via adding the habit variable to the TPB’s main model. In the current study, which focuses solely on water curtailment behaviors (behavioral conservation), 343 Isfahan citizens participated. In this regard, a cross-sectional survey was conducted using a structured questionnaire, as a research instrument, and the structural equation modeling method was also applied for data analysis. The results revealed that, by adding the habit variable to the TPB's main model, the extended model can predict 75% and 51% in the variance of intention to adopt water curtailment behaviors and water curtailment behaviors, respectively. Based on the findings, the attitude and perceived behavioral control variables had a significant positive relationship with intention, whereby attitude had the most predictive power of intention to adopt water curtailment behaviors. Moreover, the habit and intention variables were significantly and positively related to water curtailment behaviors, of which habit was the most important determinant of behavior. However, subjective norm had no significant relationship with intention, and perceived behavioral control was not significantly related to behavior. Finally, policymakers are advised to develop and implement awareness-raising and education campaigns aimed at (1) creating positive attitude toward WCBs among urban households, (2) increasing their self-efficacy and self-confidence in performing these actions, and (3) improving and/or changing their water conservation habits in order to improve WCBs among urban households.

Urban governments face a number of challenges today related to water governance. As a result, a variety of water governance models have emerged involving governments, public-private partnerships, and private firms. Using a descriptive model, this paper describes how water and wastewater companies in integrated urban management are modeled, and then it suggests how the optimal type of water governance is established in Iran. This study analyzed all parameters and effective variables in continuous management of Iran's water resources, along with the set of laws and regulations that govern upstream activities and the authorities of the governing bodies. Based on institutional mapping, four scenarios were created for dividing responsibilities between government, municipality and private sector in water governance, including governmental planning, semi-centralized governance with the central government, semi-centralized governance with municipalities and decentralized governance based on local government mapping (municipalities). On the basis of the considerations, advantages, and disadvantages of every scenario, scenario 2 has been proposed as the most desirable scenario for application under the country's circumstances.

Discharge of pharmaceutical industry wastewater by organic compounds containing pharmaceutical compounds, especially antibiotics into aquatic environments is one of the environmental issues. Advanced oxidation processes such as photocatalytic process is one of the processes which has attracted attention. The aim of this study was to optimize the efficiency of the advanced photocatalytic oxidation process in the presence of NH2-MIL125(Ti) catalyst in the treatment of pharmaceutical industry effluents. In this study, NH2-MIL125(Ti) catalyst was synthesized by solvothermal method and its characteristics were investigated by SEM, EDAX, FTIR and XRD analyzes. For optimization, use of the central composite design, and the effect of pH, nanocomposite dose and reaction time variables, on the COD removal in pharmaceutical wastewater was investigated. The results of the catalyst analysis illustrated that the synthesis of catalyst was successful. Also, the proposed optimization of the model based on the correlation coefficient (R2=0.99), is quadratic. Optimal conditions of process were pH 6.9, reaction time 79 min, and nanocomposite dose equal to 0.5 g/L. At optimal conditions, 68% of the initial COD was removed. Adsorption and photolysis mechanisms are much less efficient than the photocatalytic process. In this study, the soluble COD decreased from 3100 mg/L to 992 mg/L. The effluent from this system can be discharged to the municipal wastewater collection system.

Today, industrial and sanitation wastewater production and their penetration into water resources have caused numerous challenges. Moreover, limitations on water resources used in industry, agriculture, drinking water, and wastewater have led human societies to make optimal use of available resources and treat the polluted water. This study investigated the effect of the acid and alkaline activation methods on dye adsorption by red clay. Each activated soil was used to remove methylene blue paint by adsorption method to determine the activated soil with the highest efficiency. The influential factors on adsorption, including the effects of solution pH (5-11), dye concentration (100-100 mg/L), and the amount of adsorbent (0.3-0.2 g) in adsorption of methylene blue dye, were examined on the optimal adsorbent, and the optimal conditions were investigated and determined. Then, X-Ray diffraction, measurement of porosity and effective surfaces, and Fourier transform infrared analysis were used to study the physical, chemical, and morphological properties. The results of chemical analysis showed that the soil activated with 3 M acid has the highest adsorption capacity among other activation methods. According to the detection analyses, the surface area of the clay increased after the acid activation operation due to  some of the bonds in the structure of the clay breaking (results of Fourier transform infrared) and the opening of the plates (scanning electron microscope images). These factors increased the uptake of activated soil significantly (27 to 81%) compared to raw soil. The adsorption behavior of the adsorbent showed that the adsorption isotherm is consistent with the Langmuir equation model. The results of the reusability study showed that the adsorbent is reusable. Results also showed that the modified soil is an effective adsorbent to remove methylene blue from aqueous solutions.

Using pressure reducing valves to reduce the pressure in water distribution systems to the minimum of required value is one of the most effective ways for leakage reduction. Valve opening/closing, switching a pump on/off and water consumption fluctuation by a large consumer cause transient flows. Interference between transient flow and a PRV with constant needle-valve setting may intensify pressure waves in WDS. Applying smart PRVs can limitpressure fluctuation. In this research, Input-output feedback linearization method has been used for smart PRV control. The results of this method have been compared with PRV with CNVS and proportional-integral-derivative controller. A theoretical network taken from references was used to evaluate the proposed methods. Network demands include normal consumers and an industrial large consumer. Water hammer caused by consumption variations, PRV with CNVS operation, IOFL method and PID controllers were modeled in Simulink. PRV outlet head fluctuation in PRV with CNVS is 18 to 28 m in PID controller and in IOFL method are 26 to 28 m. Also, the results showed that the IOFL method has smoother and less fluctuation than PID. Root-mean-square error for PRV outlet head in CNVS, PID controller and IOFL is 1.6, 0.32 and 0.28, respectively. Therefore, IOFL method has less error and better performance than PID. Also, this method has simpler computational operations by converting nonlinear system equations to linear equations.

Atrazine is one of the most widely used herbicides in the country, including Khuzestan province. The presence of this herbicide in aquatic environments poses a serious threat to human health and the aquatic ecosystem. Atrazine is an endocrine disruptor and is considered a carcinogen. The half-life of this herbicide in water and soil is between 20 and 50 days, that depends on the temperature and pH. Therefore, the present study aimed to determine the pesticide atrazine in agricultural drains and water of Karun and Dez Rivers. In order to measure the concentration of atrazine in agricultural effluent and Karun and Dez River, 15 stations upstream and downstream of the river were used. Determination of atrazine herbicide concentration was used by high performance liquid chromatography equipped with ultraviolet detector at maximum absorption wavelength. Construction of stock solutions was done by adding standard atrazine solution at concentrations of 1.5 and 0.5 ppm, 0.1, 0.05, and 0.05. Data analysis was performed using Excel software. The results showed concentration mean of atrazine in the downstream station (9, 11, 12 and 15) decreases compared to the upstream statin (1, 3, 5 and 6). Maximum concentrations of atrazine in summer, winter, autumn and spring were measured with 55.16, 53.02, 111.51, 49.86 µg/L, respectively, which is beyond the standard of the environment organization (MCL=3 µg/L). Liters and different seasons of sampling are about 94.56%, 94.34%, 94.13% and 93.98% higher than the WHO standards. The results showed that the amount of atrazine herbicide in most water samples of Karun River is beyond the standard and WHO and EPA regulations. The Karun River was observed. Maximum concentrations were observed in maxing point of Karoon and Dez Rivers (station 1) followed by Dehkoda agro – industry (station 6) upstream.