مجله آب و فاضلاب
پیاپی 138 (فروردین و اردیبهشت 1401)

Restriction of freshwater resources is one of the major challenges that humanity has always been faced with. The use of treatment membranes in effluent recovery is one of the basic solutions to deal with this global problem. Therefore, in the present study, the performance of nanofiltration and reverse osmosis membranes in Assaluyeh industrial wastewater treatment has been compared and evaluated. The membranes used in this system are of commercial type of spiral woven polyamide. The effect of flow pressure and flow rate on the membrane permeate flux, total dissolved solids, separation efficiency percentage and membrane flux reduction have been evaluated. In both membranes, with increasing pressure from 5 to 7 bar at a constant flow rate of 720 L/h, the flux enhanced and the TDS rate decreased. The separation efficiency percentage of industrial wastewater using NF and RO membranes at optimum pressure of 7 bar was obtained 92% and 98.4%, respectively, which indicates higher RO filtration performance than NF. Increasing the flow rate from 600 to 840 L/h at a constant pressure of 7 bar improved the permeate flux for the samples. The amount of TDS with rising flow rate in NF membrane showed a decreasing and then increasing trend while in RO membrane there were slight changes. Meanwhile, the flow rate had no effect on the separation efficiency percentage of RO membrane, but in NF membrane, first an increasing and then a decreasing trend was observed. The highest separation efficiency percentage with NF and RO membranes at 720 L/h flow rate was 92% and 98.5%, respectively. The study of the effect of increasing pressure and flow rate on the percentage of flux reduction showed that in RO membrane it increases while in NF membrane this parameter depends on the result of the effect of flow rate and pressure.

Monitoring the quality of rivers entering the Caspian Sea can play a key role in planning to preserve and manage the health of aquatic organisms. Mazandaran province has several rivers flowing into the Caspian Sea. Hence, the quality of 28 estuaries along the coasts of Mazandaran province were investigated in the present study using water quality indexes. Method Water sampling from 28 estuaries was performed and physicochemical parameters were measured including dissolved oxygen, pH, fecal coliform, chemical oxygen demand, biochemical oxygen demand, phosphate, nitrate, ammonia, total dissolved solids, total suspended solids, total solids, bisphenol A and nonylphenol. Then, the water quality was evaluated through NSFWQI, IRWQISC, and Liou indexes. Ranges of 1.99-18.94 mg/L and 3-12.42 mg/L were obtained in Kazemrood, Tajan, Alamkola, Kelayebon, Mahmoodabad, Talarood and Noshahr estuaries for BAP and in Chalakrood, Espirood, Chaloos, Alamkola, Fereidonkenar and Mashalakrood estuaries for NP, respectively. Results illustrated, a few rivers have high quality according to IRWQISC index. While, with the NSFWQI, IRWQISC and Liou index classification, a high number of rivers, especially Sorkhrood, Tonekabon, Noor, Mahmoodabad and Tajan were placed in the worst quality categories. The urban and agricultural row wastewaters surrounding the Mazandaran Province Rivers are the main reasons for the decreasing water quality. Studies should be undertaken on wastewater treatment and riparian ecological rivers to improve the water quality of the mentioned rivers.

One of the basic needs in urban wastewater and drainage systems is the connection of shallow ducts to deep underground tunnels. This connection is usually made through a vortex drop structure. In order to form a vortex flow, in addition to preventing the fluid from falling, a significant part of its energy is lost due to the friction of the walls. In the present study, by constructing a physical model, the residual energy head in the structure (ratio of specific energy at the output (E2) to specific energy at the input of the structure, (E1)) has been studied. Using dimensional analysis of dimensionless factors of Froude number (Fr), the ratio of total fall height to shaft diameter (L⁄D) and the ratio of sump depth to shaft diameter (Hs ⁄D) were determined as factors affecting the residual energy head in the structure. Using experimental observations, the accuracy and capability of the full factorial method to describe the residual flow energy in the structure were evaluated. The results showed that the residual energy head for the Froude number corresponding to the design flow discharge at Fr=2.18 is closest to the limit value of 1. On the other hand, for all L/D operating levels, the residual energy head values are close to 1. Moreover, the smallest difference between the values of the residual energy head and the limit value was 1 for Hs/D values between 1 and 2, indicating suitable range for the practical purpose. In addition, a polynomial equation as a function of Fr, L⁄D and Hs ⁄D was expressed to accurately estimate the residual energy head in the vortex, drop structure using regression analysis.

Overdue water and wastewater bills of clients impedes any effort by utility companies at providing better services. It is thus essential to identify the factors affecting the timely payment of water bills. The data used in this study consists of the information of the first five billing periods of 2019 and 2020 for 181578 household clients in Qom, Iran. The logistic regression and decision tree models are used for the analysis of this data. The results showed that the methods have similar performance and the accuracy of the models is close to each other and equal (72%). The highest accuracy in late and timely payments is related to logistic regression (72%) and decision tree (75%), respectively. The two methods of support vector machine and neural network have similar performance. Logistic regression method indicates that billing payment status in the previous year and the total debt amount at the end of the previous year, as well as the number of unmetered bills and the average consumption of the current year, with regression coefficients of 1.75, -0.86, -0.70 and 0.034 respectively, are the most significant factors affecting the number of timely paid bills. The results of the decision tree model show that 43% of subscribers did not pay on time in the new year, did not pay on time in the previous year. Also, 39% of subscribers who pay on time in the new year, also paid on time in the previous year and in the new year they did not have unmetered bills. Comparing the results of logistic regression and decision tree models has shown that both methods have similar accuracies. The results show that the payment behavior in the previous year, the total amount of debt at the end of the previous year, and the number of unmetered bills in the current year have a significant effect on the number of paid bills in the current year. Therefore, various monitoring, incentive, and preventive measures can be used to improve the prospect of collecting the receivables. Increasing the supervision on meter reading staff, surveying the customers with unmetered bills, providing bonuses for timely payments, installment of previous debts, assigning penalties for delayed payments, and finally, cutting the water supply as a last resort are among these measures. In addition, the Omid utilities executive order, issued in January 2021, indicates that the household customers with monthly consumption of less than 5 m3 are exempt from payment. Therefore, these customers must be monitored, and special measures should be taken to collect their outstanding debts.

With the influx of agricultural, industrial and hospital pollutants into surface and groundwater, human health and other living organisms are facing a serious threat. Zarjoub River is one of the most polluted rivers in the country, which passes through the center of Rasht and all kinds of dangerous pollutants such as nitrate, phosphate and dangerous heavy metals flow into it. Artificial wetlands are one of the low-cost and environmentally friendly wastewater treatment methods that have received a lot of attention today. In this study, the use of artificial wetlands in sequential using three different plant species of phragmites, lemna and vetiver with two different arrangements to remove nitrate in autumn of 2019 and summer of 2020 has been investigated. The results showed that the average percentage of nitrate reduction by two plant treatments was 73% and 68%, and for the control treatment it was 35%, which indicates the effect of plants in wetlands. Also, the result showed that the amount of nitrate reduction from the effluent was directly related to temperature changes and growth status of plants. The results showed that the use of hybrid wetlands can have a good removal efficiency for pollutants compared to their individual use, but the difference in plant arrangement in wetlands, although statistically significant at a probability level of 1%, had little effect on the nitrate removal process on effluent.

Nowadays, the presence of sulfurous compounds in aqueous media has become one of the most serious risks due to their high toxicity. Therefore, selecting and assessing a suitable and efficient method for decreasing or eliminating these pollutants is a vital issue. In this study, a comprehensive comparative analysis among various specific growth kinetic models of biomass were carried out to investigate the biological removal of sulfide pollutant in different bioreactors. For this aim, three types of bioreactor systems, including activated sludge without nanoparticles, in the presence of silica nanoparticles, and graphene oxide nanosheets were employed. Batch process experiments were performed to investigate the effect of different concentration of sulfide pollutant on the specific growth rates of biomass and also to study the growth of biomass during 14 days for all three bioreactor systems. Moreover, different biokinetic models, such as Monod, Haldane, Andrews and Noack, Yano and Koga and Webb were compared using obtained experimental data in a batch activated sludge process. According to the results, the maximum specific growth rates of EM, SS and GO bioreactor systems were mmax= 0.1871, 0.667, and 0.1277/ day-1, respectively. The Yano and Koga kinetic model had better fit with the experimental specific growth rate data than the other models thorough sulfide concentrations ranges with the correlation coefficients (R2) of 0.954 0.965 and 0.941 for EM, SS and GO bioreactor systems, respectively. In addition, the analysis of different error functions including, SSE, ARE, HYBRID and MPSD, showed that the bioreactor containing SiO2 nanoparticles has the best performance towards the other systems. Development and using these kinetic models and predictive methods can be considerably useful and efficient due to their analyzability and investigation of different operational parameters in the biological process of pollutants removal.

The discharge of wastewater from various industries such as petroleum and petrochemical, pollute water resources. The presence of these pollutants in water resources will cause disorders in the ecosystem and it has various risks to human health. The effluent usually contains organic matter, including phenol and its derivatives. In this study, three different types of reactors were used in the activated sludge process to study the biological removal of o-nitrophenol from the petrochemical industrial effluent. These reactors include Continuous Moving-Bed Sequencing Batch Reactor, Moving-Bed Sequencing Batch Reactor and conventional sequencing batch reactor. For this purpose, the operational indicators of each reactor were investigated and optimized. For MSBR, active sludge volume ratio (30%), aeration flowrate (18 L/min), operation time (4h), pH (7), filler to reactor volume ratio (4.7 %) and SVI (89 ml/g) were considered. Also, For C-MSBR indicators such as initial volumetric flowrate (20 ml/min), aeration flowrate (12 L/min), filler to reactor volume ratio (5.8 %) and SVI (98 ml/g) were optimized. As SBR is structurally similar to the other reactors, only initial volumetric flowrate was considered (40 ml/min) and based on the results, this reactor has better SVI (88 ml/g) than the other two reactors. Finally, based on the optimized parameters, percentage removal of ortho nitrophenol from a synthesized effluent, analogous to Karoon Petrochemical company effluent, was investigated by C-MSBR. In addition to o-nitrophenol, other chemicals such as Toluene and Benzene were also present. The results show the indicators including ortho nitrophenol percentage removal (84.7%), Chemical Oxidation Demand (COD) (94%), Biochemical Oxidation Demand (94.8%), BOD5/COD (0.57) and SVI (74.45 ml/g) comply with environmental standards and the treated effluent can be used in irrigation and agriculture by addition of one more processing step.

The fast growth of technology along with the expansion of industries has exacerbated environmental pollution. The diversity and broad application of various chemicals in the textile and agriculture industries, and eventually, the release of wastewater of such activities into the environment is a severe threat for aquatic ecosystems. Advanced oxidation methods based on the production of active species, such as hydroxyl radicals, nonselectively destroy a wide range of contaminants. Among the advanced oxidation methods, heterogeneous photocatalysts using semiconductors attracted a great deal of interest. In this project, Pd doped WO3 nanoribbons on a graphene substrate were prepared via the hydrothermal method and were used as photocatalysts to degrade a textile dye (Acid Blue 92). The effect of Pd and graphene incorporation on the surface properties, morphology, and photocatalytic activity of WO3 nanoribbons was investigated using XRD, BET, SEM, FTIR, DRS, and XPS techniques. The BET results demonstrated that the synthesis of WO3 nanoribbons on graphene oxide substrate and the reduction of obtained photocatalyst in the H2 atmosphere increased the surface area of the photocatalyst up to twice its normal size. In the next step, the ability of the photocatalyst to degrade blue-acid 92 textile dye in the presence of visible light was investigated and the degradation rate was calculated. The results confirmed that the reduced nanocomposite in the presence of H2 atmosphere in comparison with other samples has the highest dye degradation rate of 9×10-3min-1 with an efficiency of 60%. This nanocomposite, with its high surface area, facilitates the adsorption of dye-molecules on the active sites of the surface, thus greatly increasing the rate of degradation of the contaminant adsorbed on the photocatalyst surface. Eventually, different kinetic models were applied to investigate the reaction kinetics, and in each case, the correlation coefficient was calculated. The results of correlating the experimental data with the kinetics equations depicted that the dye degradation kinetics according to the Langmuir-Hinschlod model has a quasi-first-order mechanism.

This paper examines the level of attention to water sensitive urban design approach in Iran, leading to two questions: a) What are the objectives of WSUD? b) To what extent is attention paid to the objectives of WSUD in teaching landscape architecture and urban design fields? The research methodology of this research is combined (qualitative-quantitative). In the first step of the research, the qualitative strategy and content analysis method were used to extract the main and secondary objectives of WSUD from resources. Then, the extracted objectives were examined as measured components, based on the opinions of the panel of experts. In the second step, in order to evaluate the level of attention to the objectives of WSUD in the academic education in landscape architecture and urban design fields, the opinions of academicians in landscape architecture and urban design were collected. In the third step of the research, Shannon quantitative entropy strategy was used to analyze the answers to the questionnaires. Shannon entropy is one of the quantitative methods based on multi-criteria decision making and has an important role in information theory for data processing in content analysis. The analysis of the answers to the questionnaires using Entropy Method shows that among the five main components of WSUD, in urban design and landscape architecture education, the performance component is much more important than other components and the two components of water amenity and water supply are in second rank, water quality is in third place and water quantity is in the fourth position. Among the 20 sub-components, the weight of 14 components (equivalent to 70% of the components) is the same and insignificant, which shows that little attention is paid to them in the process of landscape architecture and urban design education in Iran. The results indicate that the components with quantitative nature have a low position in landscape architecture and urban design education, while many of the qualitative components had attained higher weight than the quantitative components. This shows that the education of landscape architecture and urban design in Iran, especially in water field, is mainly based on theoretical concepts and qualitative issues, and is not successful in preparing graduates of these fields to face the challenges in real projects. To close this gap, it is recommended to review the course descriptions of these two fields and determine how to enhance the knowledge of the teachers about the importance of water for further studies.

Today, environmental pollution and less accessibility of freshwater have been a serious challenge due to industrialization and urbanization. Therefore, the aim of this study was to investigate the synthesis of aminated magnetic graphene oxide (m-GO-NH2) from Typha latifolia and its application for Pb (II) removal from aqueous solution. The m-GO-NH2 was synthesized from steam of T. latifolia by using CVD and applied to Pb (II) removal. The structure of synthesized nano adsorbent was characterized by using SEM, FTIR, AFM, Raman spectroscopy and pHZPC. After finding the optimum amount of pH, central composite design was applied to survey the effect of time (X1), initial concentration of Pb (II) (X2) and adsorption dosage (X3) for Pb (II) removal from aqueous solution. Two quadratic models were developed to estimate the amount of Pb (II) removal efficiency with design expert software.  According to the SEM, FTIR, AFM, Raman analysis, the mGO-NH2 was successfully synthesized. The amount of 164.29 mg/g of Pb (II) removal at operation conditions (X1=120min, X2=35mg/L and X3=20 mg/L) indicated an excellent agreement with the model amount predicted. Regarding the thermodynamic studies, the adsorption procedure was spontaneous and endothermic and followed Freundlich isotherm and Redlich-Peterson (R-P) equations. In conclusion, it is affirmed the m-GO-NH2 as synthesized from T. latifolia, has a high capability for use in adsorption of Pb (II) from aqueous solution.