Water and Wastewater
Year:2012 | Volume:23 | Issue:4 (84)|Papers Count:17

In this study, Particle Swarm Optimization (PSO) algorithm has been used to calibrate CE-QUAL-W2 model as a water quality simulation model. PSO algorithm as an optimization technique is applied to optimize the objective function of automatic thermal calibration process. Sum of the absolute difference between simulated results and field data in monitoring stations in Karkheh Reservoir has been considered as an objective function.With sensitivity analyzing, the most significant parameters have the most influence on the temperature profile in Karkheh Reservoir have been identified. These parameters were wind sheltering coefficient (WSC), extinction coefficient for pure water (EXH2O), solar radiation absorbed in surface layer (BETA), and empirical coefficients of wind speed function (AFW, BFW, and BFW). The efficiency of the automatic calibration model (PSOCE_ QUAL_W2) has been evaluated with the hypothetical data in Karkheh reservoir. Then the evaluated model has been applied in vertical temperature calibration in Karkheh Reservoir during 90 days. The vertical temperature profiles of the model results agree closely with the set of field data.

The heavy metals are nonbiodegradable that can accumulate in living tissues which cause cancers and neural problems in human. From an environmental health point of view, it is therefore necessary to remove them from aqueous solution and wastewater. In this research work, nanoporous silica SBA-15 was synthesized by hydrothermal method and then functionalized by three different concentrations of 3-aminopropyltriethoxysilane, namely 4 [(NH2 (4mM) -SBA-15], 6 [NH2 (6mM) -SBA-15] and 8 [NH2 (8mM) -SBA-15] mM, in order to be used as adsorbent for lead, copper and cadmium ions removal. The materials have been characterized by means of XRay Diffraction (XRD), Scanning Electron Microscopy (SEM), nitrogen adsorption-desorption, and FTIR spectroscopy. The results showed that the removal percentage was increased from 46.1 to 100 for lead, from 44.2 to 79.3 for copper and from 26.8 to 67.0 for cadmium with increasing concentration of amine groups from 4 to 8 mM. Thus, NH2 (8mM) -SBA-15 was selected as an adsorbent in subsequent experiments. The effects of adsorbent dose, contact time, pH and initial concentration of metal ions on adsorption efficiency in batch system were studied. The experimental data were analyzed using the Langmuir and Freundlich isotherm models.Maximal equilibrium uptake capacity of 15.9 mg/g for lead, 13.1 mg/g for copper and 11.2 mg/g for cadmium was obtained. Consequently, the nano-structural adsorbent prepared has appropriate adsorption efficiency therefore it can be considered for the removal of heavy metal ions in future study.

Growth of petrochemical industries is caused increase producing of wastewater recently. This wastewater contains of various combinations and is a serious threat for environment. Effective treatment could be discovered coincidentally mentioned worries. So effective methods for treatment one essential active sludge processing in proper method. For kind of wastewater treatment that combination of the method with it, could be helped to omit affection contaminative measurement. In this research from active sludge processing and biofilm growth are used to treat wastewater simultaneously in petrochemical complex, Imam Khomeini port. The main goal is investigation of rate of efficiency promotion of active sludge processing in treatment of petrochemical wastewater in low temperature by usage of polyorethan foam in media clarified bond. The result showed that efficiency of active sludge processing in reducing COD with rate of %77 accompanied biofilm have increased.Also efficiency of active sludge has increased about %74.3 for omitting N- NH4 from Imam Khomeini petrochemical wastewater generally. The result of this research showed that combination of active sludge process and usage of polyorethan foam media is an efficient and sure for treatment of Iran’s petrochemical wastewater even in low temperature, of course, this method is suggested in all petrochemical complexes of Iran especially in cold regions.

Tehran, the capital of Iran, like many megacities in the world is faced with increasing freshwater demand and water resources limitation due to the rapid growth of population. In this paper, water reuse and wastewater recycling are considered as a sustainable solution for water supply and wastewater management of Tehran. A linear programming optimization model with the object of cost minimization is used to allocate water between users and resources, concerning the water quantity and quality of each one. Ultimately the economic and environmental effects of this strategy will be presented as the conclusion of this study.According to this study, improving wastewater treatment plants and control of water quality in canals and streams in order to substitute these two new resource for freshwater and groundwater have positive environmental and economic effects. The examples of environmental benefits are reducing pollution loads to receiving streams, adjusting increasing water demand and preventing groundwater level drawdown especially in the period of drought. In addition to the environmental benefits, although improving wastewater treatment plants and control of water quality in canals and streams need considerable investments, long usage of these two new recourses is more worthwhile.

Increasing the resources productivity using cropping pattern optimization is a proper way for agricultural development. In this study, the ideals’ realization possibility of maximizing the gross margin in compromising with reducing the water consumption, minimizing the fertilizers uses, minimizing the production risk, and maximizing the social benefits of cropping pattern were analyzed using a multi-objectives fuzzy non-linear programming model in Marvdasht City of Fars Province. In this approach, the crop area is optimized to maximize the weighted sum of fuzzy objective in the range of their given bearing bounds. Results show that in many cases the possibility of complete ideals realization in the multiple goals model in comparison with single goal patterns was not observed. Considering the outcomes and the relevant weight assigned to each of the goals by the decision maker consisting of the Fuzzy Composite Distance Function reveals that the cropping patterns base on multiple goals are superior to current patterns and even single goal pattern in supply of multiple compromised ideals. Implementation of these models in study areas has significant influence on reducing water use as well as increasing the gross margin and reducing fertilizer use and risk.

In the most of arid and semi-arid countries, the quality and quantity of available water resources play a significantly limiting role in development. In these regions, the conjunctive management is a suitable alternative that can lead to the optimal operation of available water resources. In this study, a conjunctive use model is developed in order to maximize water supply demands in 30-year period historical records. Discharge from resources, consumption priority in sectors and zones, inter-basin water conveyance plans and water demands are considered as the optimization model’s constraints. The ultimate goal of the study is to present short-term, medium-term and long-term operating policy. The sequential genetic algorithm is used to speed up the convergence to near global solution. The operating rules of surface and groundwater resources are separately developed for agriculture as well as domestic demands in the annual and monthly manner, respectively in the three above-mentioned periods. Finally, these rules are verified based on previously unused historical records.The results showed that the proposed model can effectively improve water resources potential, sustainable groundwater resources and undesirable use in agriculture sector.

Chitosan, is a biodegradable cationic polymer, which is derived from deacetylation of chitin. The present study was conducted to investigate the effect of chitosan as a coagulant aids in improving the performance of coagulant property of poly-aluminum chloride as a primary coagulant on the removal of turbidity from water.This study, was performed in a laboratory scale and using jar test apparatus in Ahwaz Water Treatment Plant.Experiments were performed with different concentrations of coagulants, pH and different concentrations of chitosan as a coagulant aids. First the samples mixed under rapid mixing condition (120rpm) for 1minute and then the apparatus set to slow mixing (40rpm) for 20 minute. After mixing the samples left for 30 minute in order to settle the sediments. The optimum pH was found 8 in this study. The optimum doses of poly-aluminum chloride in conjunction with chitosan, were 5mg/L and 0.02 mg/L, respectively. The required dosage of polyaluminum chloride as a primary coagulant be reduced upto 50% under optimum condition with chitosan. It was also found using chitosan also produced larger floc with higher settling velocity than primary coagulant alone.The results also showed that chitosan as a coagulant aid had a positive effect on turbidity removal.

The increasing trend of water demand is an inevitable problem all over the world. Considering the population growth, industry development, improvement of sanitation level and public welfare, renewable resources per capita like water is decreasing. In this paper, water demand is derived using Stone-Geary function and it is estimated using the random effects model. The used data is panel and yearly and is related to 266 household during 1382-1386 in Neishabour. Water demand is estimated using average price, income per capita, price index of goods and services and average temperature variables. The price elasticity is -0.15, income elasticity is 0.15 and cross- elasticity is -0.00025. It is shown that water demand has low elasticity with respect to income and price and it is complementary with other goods. Furthermore, the average temperature is not significant. Three scenarios are used to forecast water consumption. The results show that if the price of water does not increase, the water consumption per capita of household will increase with increase of income per capita. Also an increase in tariffs will decrease the per capita water consumption household.

Every day million liters of dye wastewater is produced in different industries that cause environmental problems.The purpose of this research was to investigate the possibility of Acid Blue 113 removal, which is one of the most consumed textile dyes, by using electro-coagulation and photo-oxidation UV/O3 processes in batch condition. Iron electrodes were used and the effect of current density, electrolysis time, pH, initial dye and electrolyte concentrations on dye removal were evaluated. Regarding photo-oxidation UV/O3 process, parameters including ozone dosage, light power, time, pH and dye concentration were determined and optimized. The results in the optimum conditions showed that in the electro-coagulation method, over 90 percent of 100 mg/L dye was removed after 5 minutes in the applied current density of 44 mA/m2, pH of 6.5 and electrolyte concentration of 3 g/L. However, in the photo-oxidation UV/O3 process, only 70 percent of 15 mg/L dye was removed after 15 minutes in pH of 9, 4 g/h of ozone and 15 mW/cm2 of power. According to the results, electro-coagulation method had better capability in comparison to photo-oxidation UV/O3 process. Although, the first method was operated with simple equipments and was more economical but had still sludge producing remained. Therefore, according to the type of industry, the proper method should be selected.

Optimal operation of multipurpose reservoirs is one of the complex and sometimes nonlinear problems in the field of multi-objective optimization. Evolutionary algorithms are optimization tools that search decision space using simulation of natural biological evolution and present a set of points as the optimum solutions of problem.In this research, application of multi-objective particle swarm optimization (MOPSO) in optimal operation of Bazoft reservoir with different objectives, including generating hydropower energy, supplying downstream demands (drinking, industry and agriculture), recreation and flood control have been considered. In this regard, solution sets of the MOPSO algorithm in bi-combination of objectives and compromise programming (CP) using different weighting and power coefficients have been first compared that the MOPSO algorithm in all combinations of objectives is more capable than the CP to find solution with appropriate distribution and these solutions have dominated the CP solutions. Then, ending points of solution set from the MOPSO algorithm and nonlinear programming (NLP) results have been compared. Results showed that the MOPSO algorithm with 0.3 percent difference from the NLP results has more capability to present optimum solutions in the ending points of solution set.

An experimental investigation of water flowing through coarse porous media in an open channel with free surface was conducted to better understand the mechanism of energy loss and changes with flow velocity. In this research, experimentally, investigate water flowing through coarse porous media in nonlinear unsteady state. To cast light on the analytical characteristics of unsteady-turbulent flow within coastal rockfill structures, an extensive research program has been carried out using the open channel flow principles. Crushed coarse aggregates with pre-determined gradations were carefully packed in a 600 mm wide flume through which, variation of pheartic surface as a result of the tail-water variation - to resume unsteady flow conditions - were optically recorded by means of a set of piezometers installed along the flume’s side-wall. Discharge rates were measured by a calibrated v-notch and the tail-water surface variations were precisely timed by means of delicate electrical equipments specially designed and manufactured for these experiments. Observations on the flow media. b) Although a third term defining effects of unsteadiness may be included in the above mentioned equation, it is of little engineering importance. c) The nature of hydraulic gradient (i) variations versus Reynolds number (Re) - which were plotted for all sets of observations - confirms existence of turbulent conditions in all experiments. d) Our unique experimentation set-up adequately resembles the actual prototype conditions.

Nowadays treated effluent reuse is very important due to the water shortage problem. The aim of this study was comparison the quality of Mashhad Aolang treatment effluent plant with wells water on that area for irrigation purpose and their effects on wheat production. In this study a total number of 24 well water and 24 treated Wastewater samples were taken, weekly within the period of six months. Totally eight wheat farms were selected at the end of wheat growing season which four wheat farms among them were irrigated with treated wastewater and the other four farms were irrigated with wells water. Heavy metals (Cd, Ni, Fe, Mn, Pb, Zn and Co) and pH, EC, BOD5, COD, TSS, nitrate, nitrite, PO4 2-, alkalinity, Na%, RSC, ESP, SAR in all samples were measured according to standard methods. Results indicated that the quality of all measured parameters in treated effluent were consistent with the agricultural irrigation standard. In comparison, irrigated with treated wastewater was more productive than well water on wheat production. In conclusion, replacing treated wastewater with continuous monitoring with well water for irrigation purposes is recommended.

Settling tanks are one of the main parts of treatment plants and different parameters are effective in the settling tank performance. In this study effects of some of these parameters such as the situation of the inlet opening as well as the existence and position of baffles in the tanks are investigated.2D numerical simulations of primary settling tanks are carried out using 2D Fluent software and the best position for the inlet to enhance the their performance found to be in the middle of the tank with optimum size of the baffle about 30% the height of settling tank at a distance about 5-10% settling tank's length.

To design an urban water network in addition to minimizing the cost, improving the water pressure is very important. Then in this paper a bi-objective optimization model for the new city of Sahand in Northwestern Iran is developed. Due to its non-linearity and the huge number of variables, the genetic algorithm has been utilized to solve it. Several Pareto solutions have been obtained and then based on the game theory approach (the area monotonic solution), the most efficient point was provided. The solution is simulated by the Water Gems software and the elements of the network are designed. This optimum solution shows a decrease of 13% in total cost in addition to the improved water pressure.

Several factors affect the selection of water and wastewater treatment plants’ location. Each factor, depends on the site situation, has different weight in decision making process. The object of this study was to investigate the application of analytic hierarchy process (AHP) in the selection of type and location of water treatment plant. In the first step of the study, two alternatives, including building a centralized treatment plant and domestic plants for different places, were assessed. Alternatives were ranked with four parameters from their preference point of view. Results suggested that the centralized water treatment plant was the more preferred choice. In the second step, selection of the plant location was performed using fourteen parameters for different locations. Because of the importance of economic issues in site selection, an index named “value index” was defined and calculated for each location. The final decision was made based on this index.