WATER AND WASTEWATER
Year:2019 | Volume:30 | Issue:1 |Papers Count:13

Urban runoff management as well as collecting and transferring surface waters are the major concerns for officials and managers in urban affairs. The Multiple components of runoff drainage systems, the close interrelationships between the functionalities of the components and the relationship between the runoff collection network and the individual and social assets within the cities lead to a doubled complication in management plans. Flooding risk is generally subjected to numerous factors and the integrated management of these factors makes the urban runoff management a multi-criteria problem. The current research offers a comprehensive method for risk management in management of surface water collection networks. The necessary measures taken to implement this method include modeling the study area in Autodesk SSA software, specifying the layer of hydrology, hydraulics, social, traffic, environment, urban appearance and structures. Weights were extracted from the ideas inquired from the urban affairs experts and based on AHP multi criteria decision-making. Eventually, the map for canals’ flooding risk was generated by taking advantage of GIS capabilities and spatial MCDM methods such as SAW and TOPSIS. The implementation of the proposed method on degree 3 and degree 4 canals in District 11 of the Tehran Municipality is indicative of high and very high flooding risks for a length of about 6% to 9% of the total canals.

Nowadays, the using modern trenchless methods for repairing sewer networks have been developed in most countries. Generally, for repairing the sewage lines using trenchless methods, bypassing the repair zone is necessary. For this purpose, the damaged tube is blocked upstream of the damaged pipe using plugs and packers, and to prevent rejection, the sewage is pumped to the downstream pipes. However, the pumping of sewage is a very costly task. In this study, an effective method named “ minimum pumping” (MP) is suggested using the capacity of the upstream pipes and manholes. In the proposed method, the timing needed to repair the damaged tube can be managed in a way that the cost of pumping is reduced. Here, as a case study, sewage pipes in Nazar Boulevard and Mirzakochek Khan Boulevard in Isfahan City in Iran have been repaired using the proposed method and the results are presented and analyzed. The results indicated that the proposed method is an effective method for reducing the cost of repairing in sewage networks. Using the proposed method, the pumping rate and, consequently its costs, were reduced from 35% to 50% for Nazar Boulevard sewer network and from 70% to 85% for Mirzakochek Khan Boulevard.

Qom city (located in the central desert of Iran) has always faced the problem of water shortage. In recent years, due to various reasons such as urbanization, increased immigration and tourism prosperity, this problem has become a more serious trending water crisis. In spite of the steps taken to maintain the sustainability of potable water, predictions indicated that if the existing situation persists, in 2022 the city will be in a state of unstable water. To overcome this dilemma, this paper aims to identify and present sustainable urban Potable water policies on a thirty-year horizon through system dynamics and the use of Vensim software. These policies are generally presented in two parts: Supply and Demand. The supply policies include separation of potable water from non potable water, using fresh water or wastewater, and managing the water supply losses. In demand management, the policies are to control the population, control the pattern of domestic demand, and control the Exempt Demand. The new policy investigated and proposed by this research which is proportional to the problem was the separation of potable water from non potable water and control the exempt demands over time and their impact on the sustainability of urban potable water.

Comprehensive evaluation of organization performance is one of the most powerful tools for decision making. It helps managers to gain necessary information about the status of their organization. One of the most widely welcomed models in this regard is the Balanced Scorecard Model which provides comprehensive evaluation for various aspects in the Water and Wastewater Corporation. The present study was a descriptiveapplied research in terms of objectives. The objectives included selecting a comprehensive evaluation pattern, recognizing and ranking the indexes and main substandards for evaluating the comprehensive performance with BSC model denoting various parts in water and wastewater corporations. The model was used in West Azarbayjan province water and wastewater company as a pilot. Data collection was based on the library and field study via 3 types of questionnaires and interview with staff, financial staff, and by the customers of the given company. Based on the correlation and regression coefficients, the mean variables test and the fuzzy method showed that the BSC fields are in the order of priority in the performance of the mentioned company. These included internal processes, learning and growth, and customer and financial perspective. In the regression dependent variable model, the performance of the company and independent variables included various variables in fields of the balanced scorecards, and the result showed that the most effective factors on the company performance were decreasing the unnecessary costs, increasing and developing new facilities, finding new custumers, providing infrastructures, and organizational resources through learning, increasing customer satisfaction, enhancing the efficiency and quality of the internal processes.

Estimating of the peak velocity of pollutant in a flow using hydraulic and geometrical parameters is very important in predicting the pollution transport in rivers. Suitable empirical equations are developed, none of which is reliable enough in estimating the peak velocity of pollutant before a thorough calibration. So, in this research artificial intelligence methods are used for this purpose. The objective of this research was to predict the peak velocity of pollutant by Group Method Data Handling (GMDH) methods and an intelligent hybrid method (GMDH-HS). The result of these methods were compared to the best regression equation. The dimensionless relative discharge (Q'a), dimensionless drainage area, the ratio of discharge at the section at the time of measurement to drainage area (Q/Da) and the reached slope (S) were taken as input parameters to these models. These data were collected from several different rivers in the United States. Mackey-Glass standard function was used to evaluate the performance of the GMDH and GMDH-HS models. The results indicated that the proposed models predicted the peak velocity of pollutant precisely (CE GMDH =0. 9328, CE GMDH-HS =0. 9038 & CE Vp Equation=0. 3802) and these models are more accurate compared to the best nonlinear regression equation.

In recent years, the increase in car production, population growth, urbanization and significant expansion of the use of private vehicles has led to the development of more and more carwash facilities in all cities. Regarding the carwash wastewater pollutants, treatment of such wastewater can be a big help in protecting surface and groundwater resources. The wastewater needed for this research was taken from the output of carwash using hand washing method and composite sampling. The aim of this study was to determine the efficiency of combined chemical coagulation and UV/H2O2 processes in treatment of carwash wastewater. To reduce the settleable solids, samples underwent a 2-hour settlement. Then in the first step of coagulation process, the optimum conditions for pH and the ferric chloride dose were obtained using jar test. The effluent of coagulation stage was introduced to UV/H2O2 reactor under the influence of ultraviolet radiation. Finally, required parameters such as COD and BOD5 in the effluent of oxidation process were measured at the designated times. Results showed that the COD removal efficiency of 70% and 93. 2% was achieved in coagulation and UV/H2O2 process, respectively. The overall efficiency of this system based on COD and BOD5 removal was obtained as 98% and 97. 5%, respectively. Overall, the recommended combined system is effective and robust to treat carwash wastewater to meet the standards of effluent discharge.

Many types of dyes are toxic, carcinogenic, non-biodegradable due to their complex aromatic structures and their water solubility and accordingly, they should be removed from wastewaters. In the present research, hexagonal mesoporous silicate HMS was synthesized by sol-gel method and after modification by natural polymer chitosan (Ch-HMS), it was applied for the removal of direct yellow 86 from aqueous media. The characterization of synthesized HMS and chitosan modified HMS were analyzed by some basic analyses such as SEM, FTIR, XRD and BET. The effects of pH, adsorbent dosage and contact time on the removal of direct yellow 86 were investigated. The results revealed that the maximum adsorption of dye was about 92% which was obtained by 0. 075 g of Ch-HMS composite at the pH of 2 and for 60 min contact time. The equilibrium data of experiments were studied by Langmuir, Freundlich, Elovich and Temkin isotherm models using linear regression. The Langmuir model with the maximum adsorption capacity of 71. 43 mg/g was the predominant model. Kinetic study was also performed using pseudo first and pseudo second order kinetic models where the second order model had the best agreement with the experimental data. The experimental data showed that surface modification of HMS by chitosan and formation of Ch-HMS nanocomposite enhanced the adsorption capacity of HMS and changed it into a useful and powerful adsorbent for the removal of pollutants from aqueous solutions.

High soluability of nitrate ions in water cause the dysfunction of many existing treatment methods in the removal of this very dangerous ion from aqueous media. On the other hand, due to the need for in situ treatment methods, in particular for groundwater, the replacement of old inefficient methods with new compounds is required. In this study, for the first time, the efficiency of activated dendrimer-graphene oxide for nitrate removal from an aquatic solution was investigated. Experiments were performed in a batch reactor and the main factors of pH, reaction time, and concentration of PAMAM-GO were investigated. The highest removal efficiency was obtained as 90% at 0. 025mg/L activated dendrimer-graphene oxide, pH of 7. 5 and 15 min reaction time. The results showed that nitrate removal by activated dendrimergraphene oxide is correlated with nanocomposite concentration, contact time, pH and initial concentration of nitrate. It seems that ion exchange between nitrate and chloride is the main mechanism of nitrate removal by activated dendrimer-graphene oxide according to functionalization of activated dendrimer-graphene oxide using hydrochloric acid. This method can be used as a suitable method for in situ removal of nitrate from water and wastewater due to the desirable ability of the nanocomposite and its optimal compatibility with the environment.

The use of wastewater and gray water for agribusiness is recently growing, and it is essential to investigate the risks associated with its use. Heavy metals in wastewater, even in small quantities, are among problems limiting the use of wastewater in agriculture. This is due to the high agglomeration coefficient in the environment, degradability and long shelf-life which cause the severity of toxicity and contamination of the soil during irrigation. In this regard, the Phytoremediation technology can be advantageous due to its environmental compatibility and environmental refining power. In order to investigate the power of sweet sorghum, urban wastewater was used to irrigate the plant. First, wastewater was analyzed in terms of 38 factors. By adding cadmium, lead and arsenic to wastewater, three treatments of 0. 1, 1 and 10 mg/l of these metals were created in urban wastewater and for 12 weeks the respective pots were irrigated with appropriate replication. Samples of root, stem, leaf, seed, soil and drainage of pots were collected separately for analysis of acid digestion and grafting to the atomic absorption system and the results were compared by statistical methods. The results showed that accumulation of cadmium and lead in sorghum is more than ten times higher than that of arsenic. On the other hand, the absorption coefficient or ability of the plant to absorb the elements has decreased rapidly for cadmium and lead with increasing concentration in the soil. In the case of arsenic, the absorption coefficient increased with increasing concentration in the soil. Regarding the amount of material accumulation, the ability of all tissues in the accumulation of cadmium and lead was the same and in the case of arsenic, the root accumulated more than aerial parts. This study showed that the heavy metals accumulation pattern in sorghum, the final amount of accumulation, the absorption coefficient and its changes relative to the environmental concentration are different for various elements. According to the final concentration of accumulation and absorption coefficient, the sorghum plant is suitable for the purification of cadmium and lead from low concentration effluents which are commonly found in urban wastewater. This can prevent the accumulation of these pollutants in soil.

Water is considered a passive defense means. One of the strategies of enemy invasion, especially in the border areas of the country (such as South Khorasan) is to dominate the minimal water resources in the region. Also, the growth in demand and the constant volume of renewable fresh water resources has led to water scarcity which in turn has provided the grounds for the development of science and economics theories on the issue of scarce resources allocation. The purpose of this study was to investigate effective factors on drinking water consumption pattern for scarce resources using experts' opinions and employing Analytical Hierarchy and Topsis Analysis (TOPSIS) techniques. The results showed that the strategies of applying tariffs in accordance with the conditions and costs of producing and distributing, preparing and applying water efficiency labels on all equipment and household appliances, using educational catalogs and advertising warnings to reduce water consumption, installing equipment for water use in schools and educational centers and some mosques, and comprehensive water resources (which we lack in Iran) are the best strategies among drinking water consumption patterns in arid regions. The results of this study indicated that the combination of the Hierarchical Analysis Process model and the Ideal Likelihood Option (TOPSIS) can be used to examine and prioritize the patterns of drinking water consumption.