مجله آب و فاضلاب
پیاپی 79 (پاییز 1390)

New group of polymers have been synthesized that are conductive of electricity so they are called conducting polymers. One of the most conducting polymers is "polyaniline". In the present study, polyaniline was synthesized by oxidizing aniline monomer under strongly acidic conditions using potassium iodate as an initiator of oxidative polymerization. Synthesized polyaniline as a powder used as an adsorbent to remove chromium from aqueous solution. Experiments were conducted in batch mode with variables such as amount of polyaniline, chromium solution pH and adsorbtion isotherms. Due to presence of Cr (III) in solution after using polyaniline, removal mechanism is the combination of surface adsorption and reduction. It seems that polyaniline reduces the Cr(VI) to Cr(III) and adsorbs the Cr(III) and a part of remaining Cr(VI). It is well known that nitrogen atom in compounds of amine derivative makes co-ordinate bond with positive charge of metals due to the presence of electron in sp3 orbital of nitrogen. The majority of total chromium removal occurred at 30minute for polyaniline and the optimum time for hexavalent chromium removal was about 5 min. Polyaniline has the maximum total cheomiume removal at pH, 3-9. The maximum hexavalent chromium removal occurred at acidic pH for polyanilines. The equilibrium adsorption data for polyaniline fitted both Freundlich’s and Langmuir’s isotherms. This research shows that polyaniline can be used as an adsorbent for removal chromium from aqueous solution.

Chromium is one of the heavy metals that is found in industrial effluents and is very toxic for human and environment. In this work the removal of hexavalent chromium by using of adsorption onto strongly basic anion was investigated. Various parameters such as pH, initial hexavalent chromium concentration, contact time and resin dosage were studied. Experimental data were expressed by Langmiur and Freundlich isotherm Pseudo-first order, Pseudo-second order and modified Pseudo-first order kinetic models. The results showed chromium removal was increased by increase of contact time and resin dosage, while decreased by increase of pH and initial hexavalent chromium concentration. At contact time equal 120 min, resin dosage 0.2 g/100 ml and initial hexavalent chromium concentration of 30 mg/l, by increasing pH from 3 to 11, removal efficiency was decreased from 93.56 % to 69.12 %. In addition, by increasing contact time from 5 min to 120 min, removal efficiency was increased from 39.51 % to 94.41 %. The results also showed hexavalent chromium sorption follows Langmiur isotherm model. Pseudo second order models best describe chromium removal by using of adsorption onto strongly basic anion resin. The results revealed that removal of hexavalent chromium from aqueous solution by using of adsorption onto stringly basic onion resins can be done quick and effective.

This study evaluated the efficiency of Electrical coagulation process in removal of COD, turbidity, detergent and phosphate from carwash effluent. An experimental study in laboratory scale was carried out and a glass tank with volume of 3 liters (effective volume of 2 liters) containing 4 electrode-page iron and aluminum (AL-AL, AL-Fe, Fe-Fe) were used. Electrodes were connected to a power supply with using bipolar method to convert alternative electricity to direct current. Daily samples were collected from different carwash effluents. Initial pH of samples were reported between 7 to 9.At first different tests were performed on primary samples. Percentage of removal was calculated in range pH and electrical potential of 11, 7, 3 and 30, 20, 10 volts respectively. Reaction times were set 90, 60, 30 minutes with middle intervals of 2 cm. The results showed the efficiency of COD removal in the optimum range of pH=3, voltage of 30 and retention time of 90 minutes with iron electrode was more 93% also the capacity of detergent removal for this process in optimum pH of 7, voltage of 30 retention time of 90 minutes with iron electrode was 94%. The highest phosphate and turbidity removal efficiency in pH of 7 after 90 minutes retention time, voltage of 30, with aluminum electrode reached more than 99%. According to the results obtained electrical energy consumption in aluminum electrodes was less than others. However aluminum is more expensive than iron and the difference in energy consumption between iron and aluminum can be ingnored. Apart from that COD and detergent removal efficiency of iron electrodes is higher than aluminum electrodes therefore, using iron as the electrode is more economical and recommended. Altogether it was found that this method can be use as a safe and convenient method for treating carwash effluent and according to the high removal efficiency of process, effluent can be discharged safely into the environment.

The endotoxin is one of pollutants with lipopolysaccharide structure which release from gram negative bacteria and cyanobacters. The aim of this study was removal of endotoxin from water using catalytic ozonation by bone char. The endotoxin for experiments have extracted from Escherichia coli bacterium cell wall by Stefan and Jan method. Chromogenic limulus ambusite lysate method in 405-410 nm wave length was used for analysing of endotoxin. The ozone have analysed by potassium iodine method. Results of the research shown endotoxin removal rates using heterogenous catalytic ozonation were 6.0 Eu/ml.min and 0.5 Eu/ml.min for grey bone char and white bone char, respectively. The efficency of the process was found eighty percent. Primary concentration of basic compounds had no effect on endotoxin removal rate. Therefore, endotoxin removal kinetic of reaction is a zero order reaction. This study revealed that ozonation process using bone char is more efficient than other proposed methods such as ozonation or chlorination and can be used successfully for endotoxin removal from water as a efficient method.

Cyanide is a highly toxic species that found mostly in industrial effluents such as electroplating, metal mining, metallurgy and metal cleaning processes. Discharge of it into the enviroment causes very health impact. Purpose of this study was, determination of sonochemical technology for cyanide removal from aqueous solutions in the presence of hydrogen peroxide. In this study, a productive set of 500w power ultresoun waves with two frequencies 35 kHz and 130 kHz were used. Experiments were performed using different initial ratio CN-/H2O2 1/1, 1/3 and 1/5 and at initial cyanide concentrations varying from 2.5 to 75 mg/L. The effects of parameters such as pH, time and initial cyanide concentration on the sonochemical degradation have been studied. The results of the study showed that the maximom removal efficiency of cyanide was achieved 85% by sonochemical technology at frequency of 130 kHz, during of 90 min, at pH of 11, at initial cyanide concentration of 2.5 mg/l and with initial ratio of CN-/H2O2 1/5. it was also found the rates of cyanide degradation under different conditions were quite low, and also the rate of cyanide degradation was high at first but later substantially reduced. The efficiency of cyanide removal had direct relationship with pH, frequency, hydrogen peroxide concentration and time, and it had reverse relationship with cyanide concentration.

As long as oil is used, the risk of an oil spill exists. Rapid economic growth has caused a significant increase in fossil fuel consumption in recent decades. The world production of crude oil is about 3 billion tons per year and half of it is transported by sea. Exporting oil, especially via marine fleets and increasing development of petrochemical industry, marine system is exposed to severe environmental damages. The movement of oil spill, its diffusion and hydro-environmental effects have been simulated by developing a 2DH numerical model based on non-linear shallow water Reynolds averaged Navier-Stokes (RANS) equations using Finite Volume Method.The new model deploys the relevant formulations for oil spill processes. Since advection and diffusion of oil pollution play a crucial role in oil spill flow pattern, it is important to choose an appropriate numerical scheme for the transport terms of N-E equations. In this work, a highly-accurate algorithm based on a 4th degree accurate shape function has been used for the hydrodynamic model, which is not present in similar models. The solution method is based on the alternating direction implicit (ADI) scheme. The equations are then solved by a Penta-Diagonal matrix in each half-time-step. Results from the numerical model are compared with measured values. Reasonable agreement is obtained between predicted and experimental nearshore circulation patterns.

Among the different compounds of water pollutants which generally discharge into water resources through raw wastewater and effluent, phenol is particularly important. This substance is an abundant compound which also enters into water resources naturally. Since phenol is a toxic substance and eliminating it through a biological method is difficult, using the process of Fenton Oxidation seems appropriate because of the facility and the possibility of application in different scales and also economic considerations. In this study, the efficiency of Fenton oxidation process in the removal of phenol from aqueous solutions is examined. This is an experimental study which is carried out in laboratory scale. The solution under study is prepared synthetically from different phenol concentrations. The optimized parameters in Fenton process including pH, reaction time and dosage of H2O2 and Fe2+ were considered. Phenol concentration is measured using a spectrophotometer (UV-Vis) according to procedure of the standard method book. In the Fenton process, maximum phenol removal was found 96 % at following conditions pH=3-4, reaction time =30 min, 0.5 molar H2O2 and 0.03 molar ferric sulfate. The results of this study showed that Fenton Oxidation process has a high efficiency in the removal of phenol from aqueous solutions.

The water resources pollution by municipal and industrial wastewater is a considerable problem. In this research, the efficiency of Holly, Sallow and Poplar sawdust as simple, economic and abundant materials were studied for the removal of cyanide from aqueous solutions. The synthetic polluted water samples were prepared by using of sodium cyanide in distillation water with concentration of 10, 30 and 50 mg L-1 and effects of saw dust size (mesh of 20 and 70) and contact time (10-140 min) were studied. The results showed that the sawdusts had a uniform efficiency (60-70% and 71-83%) at 30 and 140 min. respectively. Also obtained results showed a direct relation with contact time and cyanide concentration and reversed relation with sawdust particle size. The results showed that the optimal contact time is 30 min. In this condition, the averages of adsorption capacity were obtained 1.25-1.38 and 1.34-1.52 mg CN/g sawdust for mesh 20 and 70 respectively. Based on the results, its availability and cheapness, the application of sawdust as an absorbent for the removal of cyanide from aqueous solutions is recommended.

The present study tries to apply the “Partial Adjustment Model” and “Random Effect Model” techniques to the Stone-Greay’s linear expenditure system, in order to estimate the "Residential Seasonal Demand" for water in Arak city. Per capita water consumption of family residences is regressed on marginal price, per capita income, price of other goods, average temperature and average rainfall. Panel data approaches based on a sample of 152 observations from Arak city referred to 1993-2003. From the estimation of the Elasticity-price of the residential water demand, we want to know how a policy of responsive pricing can lead to more efficient household water consumption in Arak city. Results also indicated that summer price elasticity was twice the winter and price and income elasticity was less than 1 in all cases.

The aim of research was analyzing the quality management based on EFQM model and required procedures for access to desired state in the Water and Wastewater Company of Semnan. The primary objective of this study was to determine score on basis EFQM model and recognizing weakness points and giving solutions for elimination its weakness. The statistical population size was the Water and Wastewater Company of Semnan province and sampling strategy was random classified. The information was collected by question aires and was classified in related table and analyzed by use of appropriate statistical (descriptive and comprehensive) methods.The results showed that principles of EFQM model has considered to some extent in the Water and Wastewater Company of Semnan province but still needs more research for its application in this company. Finally a few practial suggestion and recommendation were made.

Crude oil is a very complicated composition and contains thousands of hydrocarbons with different structures. This study measured LC50 of crude oil in water samples taken from zayandehrud dam and treated water from Isfahan water treatment plant with different chemical and physical characteristics. Different crude oil concentrations (5 to 100 mg/l) were prepared in water samples that each contains ten Daphnia. The numbers of live Daphnia were counted 4, 24 and 48 hours after adding different crude oil concentrations. The results showed that at low turbidity and TDS, crude oil was much more toxic to Daphnia.

This research which is based on experimental work, devoted to study the improvement and stabilization of dune sands in order to create strong layer and stabilize slope and floor construction of sewage Lagoons. Materials used stabilizing these soils are residual oil from the refinery. To confirm the effectiveness of the use of residual oil to improve the mechanical properties of the sand, various samples with different percentages were tested. In besides, the geotechnical and environmental tests were done. Results demonstrate that samples made with 5% oil have highest shear and unconfined compaction strength. It revealed that in compare with natural samples, cohesion and loading capacity highly increased and permeability decrease well. Percentage of fine aggregate, minerals and durability of oil in soil material were also investigated. Finally, effects of sewage on the samples were analyzed, and performance the oils were evaluated in order to use in lagoons.

The level of the Caspian Sea as the world's largest limited river basin is constantly fluctuating. The Importance of forecasting the Caspian Sea water level, in order to few meters fluctuation in recent decades and preventing future loss is considered to be essential. The agentes of water level regulator in Caspian sea are hydro climatology factors such as input series including rivers, rainfall and underground water and output including evaporation and discharge to Ghareboghaz gulf. Statistical techniques were used for modeling processes. Fuzzy techniques were also used for identification of the system and the time series prediction. In this article, a prediction of level fluctuating of this water area was suggested using combination of statistical combining statistical techniques and Fuzzy Systems. The Results of prediction experiments is exerted on the past data and advantage of the proposed method was shown according to the accuracy. Finally a 10-year forecast of the Caspian Sea level was presented.

Today, water scarcity is one of the main problems around the world, especially in arid and semi arid regions. Iran is a country that is now faced with water scarcity. One of the effective solutions for water management in arid catchments is determination and analysis of water balance components. So this study has focused on determination of water balance components in arid-mountainous catchment of Manshad in Yazd province, during 2006-2007 cropping season. To estimate actual daily evapotranspiration (ETa) of the region, time series of MODIS images were acquired and used via the surface energy balance algorithm for land (SEBAL)methodology. Annual ETa then was calculated in the form of a pixel by pixel basis map. Also annual precipitation (P) and runoff (R) were calculated using rain gauge and hydrometric station records, respectively. Inaddition soil water storage of the catchment was estimated using double ring installation and infiltration rate measures. After determination of annual P and R, the ET component was calculated as the residual of water balance equation. Then the calculated ET was compared with the estimated ET of SEBAL methodology. Comparisons show the adequacy of SEBAL in estimation of actual ET at the studied condition. Finally, the results of the study show that a large portion of catchment available water wastes through evapotranspiration, nearly 540 mm. The runoff and soil storage amounts of the studied year are about 117 and 125 mm, respectively.

There are many methods for increasing efficiency of turbidity removal such as tube settler, rotating plate or gradient parallel plate. In this study was evaluated conventional sedimentation basin which equipped by lamella system. The pilot used in the study was made up of poleax glass hexagonal having effective height of 1.2m with hydraulic diameter of 50-80 mm. The slope of sedimentation basin was 600 at the basis of horizon. The lamella system was installed onto a segment which located 150 at the basis of center of sedimentation basin. The pilot was located in Isfahan Water Treatment Plant. In fact the segment isolates sedimentation basin into two compartments, first with lamella and another without it.The turbidity of influent and effluent in two compartments were evaluated by SPSS software and T-Student.The result showed that at same condition without lamella, the minimum, maximum and average turbidity removal efficiency in Isfahan Water Treatment Plant were about 0.9%, 54% and 18.9% respectively. But in compartment equipped by lamella system The removal were about 20%, 65% and 35.3%. It can be concluded that the turbidity removal efficiency will be increased if the sedimentation basin would equipped by lamella system.