مجله آب و فاضلاب
پیاپی 135 (مهر و آبان 1400)

Water pollution with petroleum compounds is one of the most important environmental problems in oil-rich countries, due to its adverse effect on soil, water, and human beings. The hydrophilic hollow fiber membranes were produced by polymer blending of polyamide imide and sulfonated poly ether ether ketone. Membrane structure and function were investigated by field emission scanning electron microscopy analysis, N2 permeation, overall porosity, collapse pressure, water contact angle, pure water flux tests. A membrane bioreactor system was used for oily wastewater treatment. From FESEM, a more open structure with larger finger-like was observed by increasing the PAI / SPEEK ratio. Using the PAI / SPEEK ratio of 85/15, the water contact angle of the membrane was decreased from 74° to 58° which showed a significant hydrophilicity improvement. From compaction test, pure water flux of the membranes showed a gradual decrease during 2.5 h and then reached a steady state with minimal changes. During a period of about 5 hours of the oil separation through the MBR process, the plain PAI membrane and the blend PAI-SPEEK membrane showed water flux reduction of about 35% and 21%, respectively. Under 5 bar transmembrane pressure and the addition of 30 mg/l of oil spill eater (OSEII) enzyme, the oil concentration decreased from 36 ppm to 1.2 ppm in the wastewater, which represents the oil removal efficiency of about 97%. In this work, the optimum state for oil removal was obtained in terms of adding OSEII and aeration.

One of the major challenges in the operation of wastewater treatment plants is the lack of experts and the lack of use of new methods in the management of this system, which has rarely been addressed in the past. Therefore, the application of new methods in exploitation is of great importance and in this regard, in the present study, using the mass flux approach, velocity and behavior of sediment particles and sludge masses in the secondary sedimentation pond by performing Settling column experiment with observance of the sludge index range between 150 and 250 mg/L, with the preparation of 6 different concentrations of raw wastewater, effluent and returned sludge continuously for more than 18 months (551 days) and in different climatic conditions were studied. By drawing graphs of height-time, concentration-velocity, concentration- mass flux, the relationships between important parameters were obtained using MATLAB software and new mathematical and experimental models that could estimate velocity in a wide range of different concentrations were presented and observed in unusual conditions. By determining the optimal operating point (sp), the capacity of wastewater treatment plants can be increased between 15 and 20% at no cost.

Due to the increase in urban life (especially Tehran) and environmental problems, there is a great need to implement urban sewerage projects. One of the most important things about these kinds of projects is risk management. In this study, at first we reviewed similar projects and interviewed experts to identify project risk. Then we analyzed them in two methods, Analytical Network Process and FUZZY VIKOR. Prioritized risks were very similar in both methods. In ANP method, each risk was ranked but in FUZZY VIKOR method, some of the risks that were slightly different were ranked in the same category. Risks such as delays in paying bills, delays in issuing municipal permits, and other high-ranking risks need to be planned and managed. The risk of delay in payment of status statements with the ideal value of 1 in the ANP method and also with the minimum values of S, R, Q 0.011,0.011,-0.032 respectively, in the FUZZY VIKOR method, ranked first in both methods. It should be noted that the risks were identified and rated at the time of writing this paper. There are some suggestions and advice at the end.

Dyes are one of the most important industrial environmental pollutants, and therefore their removal from industrial wastewater is very important. The malachite green is a very toxic dye for the environment and humans, therefore an economical and high-efficiency method to remove this dye from water solutions is necessary. In this study, the removal of malachite green was investigated using a economical and effective adsorbent, in which activated carbon from date kernel was used. Activated carbon from date kernel was modified by Fe3O4 magnetic nanoparticles and calcium oxide. The properties and characteristics of these adsorbents were investigated using FTIR, VSM, TGA, XRD and SEM analyzes. Parameters affecting the adsorption process such as pH, adsorbent dosage, contact time and initial concentration of malachite green were optimized. Equilibrium and kinetic study of adsorption process was performed using common models. The results showed optimal conditions for adsorption of malachite green using the adsorbent are: initial concentration equal to 10 mg/l, pH=7, contact time equal to 20 minutes, adsorbent dose for AC, AC/Fe3O4 and AC/Fe3O4/CaO equal to 3, 3 and 2 g/l, respectively. The Freundlich model also has a higher ability to describe process equilibrium behavior and the pseudo-second-order kinetics model has a good ability to express reaction kinetics. The Langmuir adsorption capacity of malachite green by the AC, AC/Fe3O4 and AC/Fe3O4/CaO was determined to be 50.9 mg/g, 85.7 mg/g and 107.4 mg/g respectively. The desorption and reuse ability of AC/Fe3O4/CaO was investigated up to 8 steps, which showed that the adsorbent has the ability to be reused several times in the adsorption process. The results showed that modification of activated carbon with magnetic Fe3O4 nanoparticles and calcium oxide increases its adsorption efficiency and makes it a suitable adsorbent for commercialization.

Due to the water shortage crisis, the reuse of municipal wastewater is essential. Planting plants in the wastewater treatment process is appropriate and can help to reduce and eliminate pollution in urban and rural wastewater. This study aimed to determine the phytoremediation of lead and nickel from Ahwaz wastewater treatment plant. In this study, a completely randomized design with 4 treatments and 3 replications was used, and the laboratory activities were performed in the soil laboratory of Islamic Azad University, Ahvaz Branch. Heavy metals were measured by atomic absorption method and PG Instruments Ltd. The average amount of lead and nickel in the effluent of Ahvaz was 96.35 and 102.57 μg/kg. The amount of lead metal in the studied treatments was 17.85-96.86 ppb, and nickel content was 18.91- 102.87 ppb. In this study, the percentage of the Lewis plant's removal of lead and nickel was 62.66% and 70.18%, respectively. Also, the removal efficiency of the studied parameters by the seven herbaceous plants was 29.26% and 44.22%, respectively. The amount of nickel adsorbed by plants was higher than that of lead metal. The removal efficiency of lead and nickel metals from municipal effluent obtained by Typha Latifolica was higher than Polygonum aviculare. In total, Typha Latifolica and Polygonum aviculare plants had the ability to purify lead and nickel metals from urban effluents so that the amounts of these metals were reduced in the second and fourth treatments within 90 days.

Antibiotics are common drug contaminants due to their high levels in the effluents of pharmaceutical companies and hospitals. Tetracyclines, as a relatively inexpensive bactericidal inhibitor, are one of the most widely used antibiotics for humans and animal food and pharmaceutical supplements, which have led to their widespread release into the environment. In this paper, zeolite 4A, due to its high specific surface area and ion exchangeability has been modified to increase the adsorption capacity of tetracycline using copper ion. Impregnation method as one of the simple and reproducible methods has been used to add copper with different ratios to the zeolite structure. The adsorbent characterizations were investigated using FESEM, FTIR, XRD and BET analyses. Adsorption experiments were performed by investigating the effect of copper to zeolite mass ratio, adsorbent weight, and different pH over time. Adsorption isotherms and kinetics have been investigated to investigate the adsorption capacity and transfer mechanism of tetracycline from liquid bulk to the adsorbent surface and intraparticle diffusion. The specific surface area of the adsorbent increased from 36 m2/g to 635 m2/g during the modification process. The maximum adsorption is achieved at pH 6.8 and the weight ratio of copper nitrate to zeolite is 0.4, which according to Langmuir's theory increases from 41 to about 416 mg/g and for higher copper to zeolite ratio the adsorption capacity decreases. The Freundlich isotherm showed better agreement with the equilibrium data and the second order kinetic model predicted the reaction rate data more accurately. FTIR analysis showed that the electrostatic bond between the carbonyl and phenol groups of tetracycline with copper is one of the main mechanisms of tetracycline adsorption on the modified zeolite. The results showed that copper has significantly increased the adsorption capacity of zeolite by changing the internal structure and reducing the radius of cavities and increasing the specific surface area.

In recent years, the development of submerged membrane systems has led to the significant development of ultrafiltration/water purification markets. The study aimed to investigate the efficiency of Poly-Aluminum Chloride coagulant in removing turbidity using a submerged membrane reactor for simultaneous coagulation and flocculation of filtration and determine the optimal values of its performance parameters. In this study, the Poly-Aluminum Chloride coagulant along with lime and polyelectrolyte for water coagulation and flocculation was firstly evaluated by the Jar test in different turbidities. Also, pH (5-10), Poly-Aluminum Chloride (1-50 mg/L), and coagulant aids of lime (0.5-15 mg/L) and polyelectrolyte (0.1 to 2 mg/L) were examined. Then, a pilot-scale submerged membrane reactor was designed for coagulation, flocculation, and membrane filtration processes. Pilot experiments were used as closed systems, and then different parameters of flux, aluminum concentration in the treated water, and membrane fouling were investigated. Jar test results showed that Poly-Aluminum Chloride had a great performance in removing turbidity. In addition, the use of lime and polyelectrolyte coagulant aids improved the turbidity removal process by 3%. Furthermore, pH=8 was selected as the optimal range, and the best flux performance was obtained at turbidity less than 100NTU in a submerged membrane pilot. The flux reduction in eight hours of operation time was only 5% while this increased to 50% in turbidity above 200NTU. The turbidity removal percentages were reported to be constant and higher than 99.5%. The removal rate of total aluminum by the membrane process has been over 99%, and the type of membrane fouling is surface sediment and is reversible. Results indicated that the submerged membrane reactor along with coagulation and flocculation could be applied as an efficient method in water treatment with different turbidity.

One of the most important environmental challenges in the world is environmental pollution with toxic and dangerous heavy metals, which causes various environmental effects. Lead is a heavy metal that can be removed in a variety of methods. In this study, graphene oxide adsorbent was prepared by modified Hummers method and functionalized with aminomethyl phosphonic acid and its application for the adsorption of lead ions from aqueous solutions in a batch sorption process was investigated. The effect of several batch adsorption parameters such as contact time, pH, adsorbent dose, initial concentration and temperature were investigated. The kinetic data were analyzed by Pseudo-first-order, Pseudo-second-order and Double- exponential kinetic models. The results showed that experimental data was fitted well by Pseudo-second-order kinetic model. The Freundlich and Langmuir isotherm models were applied to describe the equilibrium data. The maximum adsorption capacity of lead ions with graphene oxide and functionalized-graphene oxide adsorbents was found to be 187.80 and 209.41 mg/g at a pH of 2.0 and temperature of 45 ºC, respectively. Furthermore, the graphene oxide and functionalized-graphene oxide adsorbents were regenerated by HCl/HNO3 solution and the adsorption capacity did not change remarkably after seven adsorption-desorption cycles.

Reuse of treated wastewater is becoming a common source of extra renewable water source in regions and countries with water-scarcity. The expansion of the urban population and the increase in the sewage networks will increase the amount of municipal wastewater. The produced wastewater can become a source of renewable water that can be used for various non-potable reuse, specifically. In the current research study, the newly established Pardis city has been selected as a case study for using recycled water (reuse of treated wastewater) for sustainable water resources management. To accomplish the overall objective of the study, Geo-land method for water reuse is employed. For this study the use of regional wastewater facility instead of centralized wastewater treatment facility as well as the related capital cost savings, job opportunities, and environmental benefits were evaluated. Statistical analyses were performed based on multiple factors and classification indicators. The results showed that the highest amount of savings and financial surplus income, 36.17% and 31.25%, respectively, of the overall savings and income as the main priority and recommendation in place of water source will occur in the study area. On the other hand, savings and financial surplus for the group that does not need to use treated wastewater is only for 1.15% of the total study area which stands as the last priority.Results obtained from this study revealed that prioritization of decentralized use of wastewater for urban areas was a highly efficient plan for a significant part of residential areas, while reducing water consumption along with economic savings and increasing regional income happened. The proposed study can also be used as a sustainable water resources management decision-making tool for Pardis city officials.

Unsustainable development and rapid urbanization have led to changes in the hydrological characteristics of watersheds, and the risk of flooding has been increased consequently. One of the solutions used for quantitative and qualitative control of urban runoff is green infrastructure and low impact development (LID) based approaches that have attracted the attention of many researchers. In this study, SWMM was used to simulate the rainfall-runoff process in region 1, district 11, Tehran. Six scenarios, including different combinations of several LID types such as Green Roof, Rain Barrel, Bioretention Cell, Porous Pavement, Vegetated Swale, and Dry Pond were developed. Then the SUSTAIN model was utilized to assess each scenario's performance. Optimal solutions were then obtained using non-dominated sorting genetic algorithm-II (NSGA-II), and a cost-effectiveness Pareto frontier curve was performed for all scenarios. Results showed that the selected solutions of scenarios one to six reduced the runoff volume by 53%, 4%, 66%, 72%, 31%, 34%, respectively. Scenario 4, with a combination of rain barrels, porous pavements, and vegetated swales with a runoff volume reduction of 72% and an implementation cost of $ 12.2 million, showed the best performance, comparing the other scenarios' corresponding optimal solutions. Scenario 6 also came in next with a 34% effectiveness and a cost of $ 7.1 million. The combined use of SUSTAIN and SWMM, in addition to the technical evaluation, helped to attain optimized, cost-effective solutions for developed scenarios as well. The results of this study can also help relevant organizations and decision-makers to design, evaluate performance, and implement costs of different LID scenarios.