WATER AND WASTEWATER
Year:2013 | Volume:24 | Issue:3 (87)|Papers Count:17

Removal of phosphorous for control of eutrophication in receiving water is necessary and of great concern for environmental protection. In this work, weak anion exchange resin with OH- was used for removal of phosphorous from model solution. All experiments were conducted in a batch system. Various parameters such as pH, initial phosphorous concentration, solution temperature, resin dosage and reaction time were studied. High removal was observed at pH 5. After 150 minute reaction time at pH 5 and 0.5 g/L of adsorbent, phosphorous concentration decreased form initial concentrations of 5, 10 and 15 mg/L to below 0.8 mg/L. Experimental data was best fitted onto pseudo-second order model. In addition it was found that film diffusion model is the main rate controlling step in this reaction. Thermodynamic studies demonstrated that removal of phosphorous is an exothermic reaction and randomness in solid-liquid surface during sorption process.

The removal of benzene and toluene from aqueous solutions by single and multi walled carbon nano tubes (SWCNT and MWCNT) and hybrid carbon nano tube (HCNT) were evaluated. In this study nanomaterials in a dose of 1 g/l and contact time 10 min with benzene and toluene concentrations of 10 mg/l and pH 7 were chosen. Synthetic samples were analyzed by GC/MS. In order to analysis data Design of Experiment (DOE) software was used. The equilibrium amount (qe) (mg/g) for SWCNT (B: 9.98 mg/g, T: 9.96 mg/g) was found higher than MWCNT and HCNT. The amount of uptake for SWCNT was T>B, that was due to increasing of water solubility and decreasing of its molecular weight. It could be concluded that recycling by heating at 105±2oc provide better adsorption performance for recycled CNTs than their initial state. So that benzene and toluene removal efficiency improved to 99.8 percent. This study showed the SWCNTs are efficient as benzene and toluene adsorbents in environmental pollution control technology.

Water resources systems simulation is a helpful tool in evaluating proposed scenarios and decision making in the development condition. Aras river basin will be facing increasing water demand in the development condition, hence, construction of new reservoirs is under study. In this study, System Dynamics approach was used to simulate the Darehrood sub catchment water resources system in Aras river basin. Then, performance indices were used to evaluate the proposed scenarios. Reliability, resiliency and vulnerability were the three performance indices presented in study where maximum value and mean value estimators mentioned in the previous studies were used to estimate resiliency and vulnerability indices. The results showed that although using maximum value estimators have been proposed in some previous studies, mean value estimators provide more useful information since they consider system performance in different states. Using these indices together with the results obtained from simulation model, can provide managers and decision makers with useful knowledge of system performance and help them to predict the behavior of the system once a failure in the system has occurred.

Water distribution network system includes multiple sources of supply and demand centers. Uncertainty in the amount of demand and supply on these systems causes many problems for decision-makers and designers. Various methods were proposed to overcome the uncertainty problem in these systems. In this study, to allocation of water in the water supply network of Zayandehrud basin, optimization with degree of conservative (degree of uncertainty) controller parameters were used. The objective function of the study was to minimize the water distribution network costs. A 15-year design and operation period (2024-2009) including two 5-year course designed to expand and create new facilities and a 10-year period of operation in the water distribution network was considered. The results showed that the total cost of development of water distribution networks in the study area is 1.31 billion dollars. Based on the findings, increased groundwater fed ponds to compensate for water shortage in the groundwater resources is recommended. In addition, Increase irrigation efficiency reduces costs related to the water distribution network of agricultural sector.

In this study the effective parameters in removal of two azo dye including Reactive Black 5 (RB5) and Reactive Red 120 (RR120) using photocatalytic method (by TiO2 nanoparticles immobilized on the concrete support) were investigated. The effect of parameters such as photocatalyst amount, initial pH, dye concentration and UV power were determined. The results showed that increase of dye concentration and decrease in pH caused decrease in dye removal rate. In order to compare dyes removal, benzene and phenol rings removal were measured in UV254 and UV310 nm wavelengths, respectively. The results in the optimum conditions showed that RB5 removal rate was more than RR120 as the removal rate was reached to 99 percent after two and half hours.

The objectives of this research were to synthesize magnetite nanoparticles (Fe3O4) and determining its efficiency in Cadmium removal from aqueous solutions. Consequently, magnetite nanoparticles were synthesized and the effect of pH, contact time, Cadmium concentration and nanoparticles amount on cadmium removal efficiency were investigated in batch system. Scanning Electron Microscope (SEM), XRD and FTIR were used to characterization of the synthesized magnetite nanoparticles. SEM results showed that the diameter of the particles is 40-60 nm. Results also showed that the optimum pH value for adsorption was 6. The adsorption capacity increased and the adsorption efficiency decreased with increasing concentration of Cadmium ions and reducing the amount of adsorbent. The magnetite nanoparticles have advantages such as high removal efficiency and short reaction time and can be used as a method to remove Cadmium from aqueous solutions.

The photocatalytic UV/TiO2 process has particular importance due to having high rate and efficiency in the removal of organic and inorganic contaminants from industrial wastewater. One of the problem of utilization of a catalyst with physical properties similar to TiO2 (anatase) is the separation of the catalyst from the wastewater effluent. In this study, synthesis of titanium oxide on the surface of alumina (particle size 150 to 200 mm) with the wet impregnation method was accomplished in order to create a catalyst with suitable physical properties to easy separation capability from industrial effluents. Hence, titanium isoprpylate compound was used and after the reaction of alumina on the surface, in order to Synthesis of titanium oxide anatase form, calcinations being done in the temperature of 500o in an electric furnace. The amount of anatase phase formation was measured by X-ray diffraction technique. Finally the removal of free cyanide in the presence of TiO2 and Al2O3/TiO2 was investigated in optimal conditions with the Change of parameters such as irradiation time of UV, the amount of catalyst and initial concentration of cyanide. Experiments were carried out by using a batch photoreactor and ahigh pressure Hg lamp (250 watt). The results indicated that a layer of anatase TiO2 formed on the surface of Al2O3 particles which its value depends on the increasing frequency synthesis. The study of the kinetic of cyanide removal process in the presence of the synthetic catalyst Al2O3/ TiO2 showed that the curve of concentration versus time is logarithmic in this process which indicated the reaction is the first order The results also showed that the catalyst TiO2 has a greater Photocatalytic activity in removal of cyanid compared to Al2O3/ TiO2 due to its higher purity and tiny particle size. However, the physical properties of Al2O3 /TiO2 catalyst including easy separation and reuse from industrial effluent in removal process, could justify economical and practical of its application.

The most important environmental pollutants are heavy metals in industrial wastewater effluents. Nickel is one of the toxic heavy metals which its high concentration causes skin allergy, heart disease and various cancers. So removal of this element from industrial effluent is of prime concern and necessary. The main purpose of this study is to compare kinetics and isotherms of nickel uptake by activated carbon (AC), sawdust (SD), hazelnut shell (SH) and almond shells (AH). Adsorbents are initially prepared to remove nickel from solutions with concentrations 2.5 to 125 mg/l. pH test results showed that maximum absorption using AC, SH, SD and AH obtained at pH 6, 6, 6 and 7 respectively. Kinetics experiments showed that maximum absorption equilibrium time at concentration of 5 mg/l of AC, SH, SD and AH occur at 60, 75, 120 and 150 minutes respectively. Kinetic models fitting results showed that for sawdust and hazelnut shells, Lagergern model and for activated carbon and peanut shell Ho et al. model are suitable and have the lowest error and highest correlation coefficient at 95 percent confidence level. The results also revealed that rate of Nickel adsorption follows this order: AH< SD<SH<AC. Adsorption isotherms studies showed that according to error factor and correlation coefficient for all of the adsorbents, Rdlych Peterson and Langmuir isotherms described data better than the others. The results also showed that equilibrium time is an exponential function of the absorption capacity.

The purpose of this study was to analyze the performance of Integrated Fixed Film Activate Sludge system in Amol industrial wastewater treatment plant to treat the food industrial wastewater. The capacity was 1700 cubic meters per day that includes physical and biological treatment, disinfection, sludge thickening, digestion and dewatering. The wastewater quality parameters were analyzed during winter 2010 and spring 2011. Using data, COD removal efficiency and kinetic coefficient such as yield coefficient (Y), half saturation coefficient (Ks), maximum substrate utilization rate (k) and endogenous decay coefficient (kd) were calculated and results indicated that except Ks other coefficient were in the range that was normally reported for conventional activated sludge. Under existing conditions at the wastewater treatment plant, COD removal efficiency range was between 98 to 99 percent. By using kinetic coefficient obtained in this study, effluent COD was estimated and sensitivity analysis was performed. The results showed that there is a direct relationship between the variation of kd and Ks with effluent substrate concentration, while the relationship between k and effluent substrate is reverse. Finally the effect of increasing sludge retention time (SRT) on COD removal efficiency was also investigated.

Estimation of evaporation values is needed for efficient management of water resources at semi-arid regions. This paper presents application of Artificial Neural Networks (ANNs), Multiple Linear Regression (MLR) and empirical models viz.: Energy balance, Aerodynamic, Penman for estimation of daily pan evaporation for Tabriz and Urmia cities. Furthermore, in order to determine the effect of each input parameter on the output variable in terms of magnitude and direction and also identify the best combinations of the model inputs, two sensitivity analysis methods i.e. the Partial Derivation method (PaD) and the Weights method have been applied on the ANNs results. The used hydrological variables include daily observations of air temperature, pan evaporation, solar radiation, air pressure, relative humidity, and wind speed. The results of the classic methods and ANN models are compared to daily observations of evaporation values. The comparison showed that there is better agreement between the ANN estimations and measurements of daily evaporation than other models. Sensitivity analysis results showed that air temperature, solar radiation and previous day evaporation have maximum effects on daily evaporation in both regions and the contributions of the other variables are insignificant.

Flooding and its damages are not only found uplift water level in a region. In other words, the depth and speed parameters together have determining the level of flood risk at each point. This subject is visible in flooded plain with low height and high speed of 2 meters per second, which damages are extensive. According to the criteria of having both velocity and flow depth in the governing equation to the flows energy, this equation seems appropriate to analysis in this study. Various methods have been proposed for increase accuracy in flood zoning with different return periods and risks associated with it in land border of river. For example, some of these methods are considered factors such as analysis of past flooding in the area affected by floods, hydrological factors and consideration of hydraulic elements affecting in flood zoning (such as flow velocity). This paper investigates the effect of flood zoning by the energy flow in the areas affected by floods. Also risk due to flood based on energy flow in each section of the river is compared by the proposed graphs of hazard interval and other done flood zoning in this field. In this study, the FORDO river has been selected as the case study. This river is part of the rivers located in the city of QOM KAHAK. The characteristics of river in upstream and downstream are mountain, young and stable and adult, respectively. Also this river in different seasons is exposed the flood damage. The proposed method in this study can be improving recognition accuracy of flood risk in areas affected by flood. Also, this method facilitate the identify parts of the river bed, that is affected by severe flooding, for decision making to improve rivers organizing.

Leachate of urban solid waste landfills is one of the most important of environmental concerns. Today, electrocoagulation is considered as a method for leachate treatment. In this process coagulants are produced during metallic electrode dissolution. In this article, treatability of old leachate of Kahrizak landfill of Tehran by electro-coagulation method was studied. The study was done in laboratory scale by using steel electrodes grades ST-12, ST-37, and CK-45 and measuring COD, SS and ORP parameters. COD removal was obtained 42.66, 34.37 and 35.2 percent for ST-12, ST-37 and CK-45 electrodes while the operation time and current were 100 min and 7.2 A for initial COD concentration of 160, 000 mg/l. COD removal increased 6.78, 4.38 and 12.12 percent when the operation time increased to 140 min, respectively. As well, COD removal was increased 38.98, 22.64 and 25.38 percent and SS removal was enhanced 16.4, 19.79 and 18.71 percent for ST-12, ST-37 and CK-45 electrodes, while the current density increased from 33.33 to 66.166 A/m2. The results also showed ST-12 electrode had the best efficiency for leachate treatment with COD and SS removal of 64.67% and 98.79% respectively while the current density was 66.166 A/m2 equals charge's loading of 46.155 F/m3.

In this study the biosorption of cadmium from industrial wastewater was studied by isolated fungal strains. For this purpose, the effluent samples were collected from leads and zinc plant of Zanjan. Then, cadmium resistant strains (yeast and a mold) were isolated by cultivation on BHI agar containing cadmium sulfate. After preparing the living and dead biomass, the effect of pH, initial metal concentration and contact time in removal of cadmium was investigated. In this study it was found that the dead biomass of yeast and mold were able to remove 86.95% and 58.65% of cadmium from the samples respectively. The results also showed that the living biomass of yeast and mold removed cadmium 29.84% and 31.94% respectively. Most removal occurred after 60 minutes of contact time. These strains were identified by 18SrRNA PCR sequencing method. Yeast strain had 99% homology with Rhodosporidium toruloides SM30and mold strain had 100% homology with Aspergillus melleus. Thus, these strains could be used for bioremediation studies in semi-industrial scale.

Acid Red206 (C40H20CaN4O8S2) is a textile dye with global usage which is found in sewage of textile manufacturing industries in large quantity. In this research the reaction of Acid Red206 (AR206) in photocatalytic analysis was carried out in water with use of Taguchi method, Qualitek-4 software and catalyst suspension ZnFe2O4/Bentonite and UV light radiation. To identify prepared catalyst, SEM image and XRD diffraction pattern were used. Based on Taguchi method the test results displayed the maximum photo catalytic activity. From kinetic view the reaction was first order and study of reaction rate was carried out with the use of first order kinetic equation and Acceptable results were gained in this consideration. The effect of factors in photo catalytic analysis such as pH, the amount of photo catalyst and hydrogen peroxide and temperature of reaction, were examined and the most efficiency in optimum conditions (pH=5, hydrogen peroxide=1ml, nonophotocatalyst=75ppm and temperature=293K) was observed. According to these results, a method was obtained for photo catalytic analysis with the use of ZnFe2O4/Bentonite catalyst and UV light radiation, which by its development in an industrial form, it can be used for analyzing the wastewater in loom or other industries.

As fluoride concentration in drinking water is one of the effective parameters in human health, finding the way to remove excess amount of fluoride from drinking water is very important in water supply projects. Today, with developing in technology and finding new methods, the use of membrane technology for producing fresh water get improved. In this study the efficiency of reverse osmosis method to remove fluoride from water was investigated. Initial concentration of fluoride, sulfate and electrical conductivity in feed water and the effect of associated cation with fluoride ion were studied. All tests adapted from “Standard Methods for Examination of Water and Wastewater”. Determination of fluoride concentration was done according the standard SPANDS method by using a spectrophotometer DR/5000. Obtain results show that with increasing in concentration of fluoride and sulfate and electrical conductivity in feed water the efficiency of RO membrane to remove fluoride reduced. In addition, this efficiency for CaF2 was higher than NaF.