جستجوی مقالات مرتبط با کلیدواژه « کدورت » در نشریات گروه « مهندسی آب »

One of the important steps in the process of removing water turbidity is the use of coagulants. Amongst the most applied materials is poly aluminum chloride (PAC) which is used to precipitate colloidal particles. The use of this compound, which contains Aluminum, in the coagulation causes some residual aluminum in the water. Natural and synthetic coagulants aid can be used to reduce the effects of overuse of poly aluminum chloride. In this study, the effect of bentonite and polyelectrolyte coagulant aid in the turbidity removal process of Babasheikhali water treatment plant is investigated. The results showed that optimum pH for turbidity removal was 8 and the optimal concentration of poly aluminum chloride at the optimum pH was 10 mg/L. In the presence of bentonite, the optimal PAC concentration decreased to 4mg/L and the turbidity removal efficiency increased to 92%. The results also showed that the combination of PAC and polyelectrolyte together can be used to reduce the concentration of heavy metals in the incoming water. Therefore, bentonite and polyelectrolyte coagulants aid can be used as a suitable option along with poly aluminum chloride to remove turbidity from the water treatment plant.

Conventional water treatment processes include screening, coagulation, flocculation, sedimentation, filtration and disinfection. Many coagulants are widely used in conventional water treatment processes. These materials can be classified into inorganic and organic coagulants. Many researches on natural coagulants were carried out in recent years. This study evaluates Tragacanth as natural coagulants aids with poly aluminum chloride (PAC) for the removal of turbidity and coliform bacteria from water Karoon River. Tragacanth is a gum that extracted from astragalus. According to results of this study, adding tragacanth as a coagulant aid improved performance of the process and experimental observations showed that by applying tragacanth as coagulant aid in optimal conditions, larger flocks are formed compared to PAC applications and the sedimentation rate was higher. In total, this study showed that dose of 0.06 mg/l of tragacanth as a coagulants aid with 15 mg/l of PAC coagulant in high turbidity (480-500 NTU) has the best performance in reducing turbidity and total coliform.

The raw water entering the water treatment plants in Guilan province is of surface water type and due to the fact that the soil of the supplying rivers catchment area is highly erodible, in heavy rains the soils washed by runoff enter the rivers or canals and increase the turbidity of raw inflows to the plants above the allowable limits provided in the design. At this time, due to the non-responsiveness of the treatment plant to such high turbidity, the operation of the treatment plant will inevitably be shut down and cause drinking water interruption in the distribution network. In order to settle the suspended solids and reduce the turbidity of water entering the next stage of treatment (filtration), sedimentation ponds are used. Baffle plates create a slow flow and are used to reduce the sedimentation distance of the particle in the sedimentation and clarification process. In this research, the use of baffle plates or flow relief walls in sedimentation ponds in a treatment plant were analyzed using simulation with Camsul software. Results were compared to normal conditions (no baffles or walls) and the feasibility of increasing the efficiency of these ponds and finally the efficiency of existing treatment plants in real volume were investigated.

In recent years, the development of submerged membrane systems has led to the significant development of ultrafiltration/water purification markets. The study aimed to investigate the efficiency of Poly-Aluminum Chloride coagulant in removing turbidity using a submerged membrane reactor for simultaneous coagulation and flocculation of filtration and determine the optimal values of its performance parameters. In this study, the Poly-Aluminum Chloride coagulant along with lime and polyelectrolyte for water coagulation and flocculation was firstly evaluated by the Jar test in different turbidities. Also, pH (5-10), Poly-Aluminum Chloride (1-50 mg/L), and coagulant aids of lime (0.5-15 mg/L) and polyelectrolyte (0.1 to 2 mg/L) were examined. Then, a pilot-scale submerged membrane reactor was designed for coagulation, flocculation, and membrane filtration processes. Pilot experiments were used as closed systems, and then different parameters of flux, aluminum concentration in the treated water, and membrane fouling were investigated. Jar test results showed that Poly-Aluminum Chloride had a great performance in removing turbidity. In addition, the use of lime and polyelectrolyte coagulant aids improved the turbidity removal process by 3%. Furthermore, pH=8 was selected as the optimal range, and the best flux performance was obtained at turbidity less than 100NTU in a submerged membrane pilot. The flux reduction in eight hours of operation time was only 5% while this increased to 50% in turbidity above 200NTU. The turbidity removal percentages were reported to be constant and higher than 99.5%. The removal rate of total aluminum by the membrane process has been over 99%, and the type of membrane fouling is surface sediment and is reversible. Results indicated that the submerged membrane reactor along with coagulation and flocculation could be applied as an efficient method in water treatment with different turbidity.

In drinking water treatments, for coagulation and sedimentation of suspended particles, several coagulants are used such as Alum, PAC and ferric chloride. In spite of their positive effect on turbidity removal, these chemicals cause some problems like corrosion and harmful by-products which result in bad effects on human and environmental health. Therefore, finding and using better and more effective materials without such adverse effects is a necessity. The aim of this research was to study the effect of chemically synthetized sodium ferrate (S.F.) in liquid state for the turbidity removal from Zayandehrud River in two conditions: normal turbidity (less than 100 NTU) and high turbidity (more than 900NTU). This research was performed in four states of 30×60, 40×60, 60×60, and 30×40; in each state, one of the water independent variables effective on water turbidity was changed. These four states were S.F. dosing rate, gentile mixing speed, rapid mixing time and pH. For the experiment design, analysis and optimization of independent variables effective on turbidity removal were used. In addition, the surface response method (RSM-D-Optimal) plus Design Expert-v10 optimization software were used for this study. Finally, in this research, according to the standard methods, the residual total Fe (due to sodium ferrate) was checked in the research in order to ensure that its value was in the allowable range for drinking water. The results showed optimum conditions as: pH of 8.5 and gentle mixing oscillating speed of 60rpm for 7min, 50rpm for 7min and 40rpm for 6min, (instead of 40rpm constant speed for 20min) and rapid mixing time of 30s with 120rpm (instead of  60s, which was conventional in Esfahan water treatment plant). In addition, the results showed that by using only 1.54mg/L of S.F. in the above-mentioned optimum condition, the water turbidity removal efficiencies were 95.17% and 99.07% for normal and high turbidity states, respectively. A comparison was made in this research between using S.F. and poly aluminum chloride (PAC) for both normal and high turbidity. The results showed the better effect of S.F. than PAC. The results also showed that the residual total Fe was in the allowable range before and after the filter (because of the reactivity of ferrate with Fe). From the results of this research, it can be concluded that using S.F. has a positive effect, technically and economically, on water turbidity removal (better effect than conventional chemicals) in both normal and high turbidity. Moreover, the results showed that residual total Fe remains in the allowable range.

Requirements of the Issue Sixteen of the Iranian National Building Code demand the protection of the drinking water network inside residential buildings over 4 stories or with more than 10 units. These buildings should aslo be supplied by a storage tank with sufficient amout of water supplying for 12 hours of consumption. Without proper regulations, the implementation of this newly building code may create problems including degradation of on-site water quality. To address this problem partially, this research has been undertaken to evaluate the effect of: incorrect operation on water meter failures, extra repairs may be needed in the distribution network, and the quality of drinking water in storage tanks installed in high-rise buildings. To carryout the objective of this study, regular field inspection of pump and reservoir system was performed, during each in each field observation water samples were collected, and all water samples were analyzed according to the methods specified in the 2005 edition of the “Standard Methods for the Examination of Water and Wastewater”. In addition to the analytical data collected from this study, the existing water quality data from Tehran water and wastewater company were also utilized. All together, routine qualitative tests were performed on 50 on-site reservoir tanks in residential high rise buldings. The results of sampls’ water quality showed that: (i) about 10% of the samples had higher level of heterotrophic bacteria with standard deviation of 56%, (ii) 8% of the samples had concerned level of total Coliforms contamination. In addition, the turbidities of higher than1 NTU in some tanks were observed that may be an indicative of an additional water water quality problems. Aside from water quality problem, direct pumping was made by 4.82% of the users in which this activity significantly contributed to an increased energy costs, water meter failures, and water pressure drops. From the preliminary findings of this study, it has been concluded that there is a potential risk for microbial contamination in drinking water storage tanks and there is also potentials for pump and meter failures and as a results additional requirements for regular maintenance. Because the accurance of these problems are inevidable, it is recommended to development a proper regulatory guidance and enforcement by Tehran’s water and wastewater company in order to protect Public Health safety.

The effluent from copper industries is important in terms of production volume, environmental pollution and cost of treatment and disposal. In addition to its economic reasons, the effluent recovery also reduces the pollutant load. Such cases therefore prove the necessity of investigating different methods for reducing water consumption and effluent generation. This study investigated the minimization of water consumption and effluent production in Khatoon Abad copper refinery plant. For this purpose, the conventional method of reducing water consumption and a new technology called water pinch were explained. The water pinch technology was examined for three pollutant indices (TSS, TDS and turbidity) in three high consumption units of Khatoon Abad copper refinery plant. For TSS, TDS and turbidity as pollutant indices, total 614, 525 and 451 cubic meters of raw water consumption per day equivalent to 40.96, 35 and 30 percent could be saved, respectively. According to the results, the pinch technology could help researchers to make decisions for reducing water consumption and according to the observations, suspended solids are regarded as the basis for reducing water consumption. Minimization of water consumption, Water pinch, Mass transfer networks, Water reuse, Total suspended solids, Turbidity.

One of the reasons for poor performance of filters is their being backwashed. The purpose of this study is to evaluate filtration process and sand filters operation after being backwashed through examining turbidity and zooplanktons in Esfahan water treatment plant. This study was conducted during 4 months in the sand filters (phase 1 & 2) of the treatment plant. Turbidity and microscopic counting were studied to assess the performance after filtration. The average for turbidity variations and nematodes & rotifers counting were evaluated in different times after backwash. Turbidity break point and zooplanktons reduction occurred after 15-20 minutes of backwash. The number of nematodes and rotifers in phase 1 after 10 minutes increased respectively by 13 and 12 numbers per liter and within 20 minutes, it reduced to 7 and 9 numbers, respectively. Also after 20 minutes in phase 2, the number of nematodes and rotifers decreased respectively by 8 and 6 per liter. This changes were significant based on t-test (p

The overall objective of this study was to investigate the turbidity and total organic carbon (TOC) of raw water entering the treatment plant and the pre-ozonation unit's efficiency is to remove these compounds. Sampling from raw water and pre-ozonation water was done within 6 months and tested according to the standard method of the method. The results showed that there was a direct correlation between total organic carbon content and turbidity that's more in winter and in February with a high turbidity of 18NTU and TOC above 7mg / l. It was also found that the average pre-ozonation unit efficiency in the removal of total organic carbon with an average ozone dose of 3kg / hr and the contact time 18 minutes, is 20.52%, The highest TOC removal efficiency was in February (35.7%) and the lowest removal efficiency (14.08%) in May. The average turbidity removal efficiency is 61%, the highest and lowest percentages eliminated respectively were in February with 85.2% and 30% in July. Therefore, to increase the efficiency of pre-ozonation unit in removing organic compounds and ... It is necessary to carefully consider the process and design factors To increase the efficiency of removal of compounds.

Enough water with proper quality is necessary for life. Drinking Water Treatment Plants (WTPs) have to provide high quality drinking water in the shortest possible time with minimal costs. In this paper, Factors affecting the process for removal of water turbidity using the Response Surface Methodology (RSM) were firstly identified and then GMDH-type Neural Networks and Bayesian Belief Network (BBN) have been used for modeling and prediction of treated water turbidity; using input-output data set. To validate the proposed model, a case study was carried out based on the data consisted of 700 sets obtained from GuilanWTP. For modeling, the experimental data obtained from the operation unit were divided into train and test sections (70% for training and 30% for testing). The predicted values were compared with those of experimental values. The determination coefficient of the predicted values for the two BBN algorithms consist of EM and GD, and GMDH model were 0.9388, 0.9196 and 0.97095, respectively. The GMDH model performed better than the BBN model in predicting treated water turbidity dosage.

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 poly-aluminum 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.

Chitosan, as a coagulant is used in water and wastewater treatment. It has similar performance in comparison with other conventional coagulants, and doesn’t have any disadvantages of them. However, its bactericidal property is lower than the metal based coagulants. In this study the potential synergistic effect of potassium permanganate, as a powerful oxidant, on the Chitosan fecal coliforms inactivation and turbidity removal has been investigated. Synthetic wastewater samples were prepared by mixing tap water with Bentonite and adding pure culture of fecal coliforms that provided by biological laboratory of Tehran University of Medical Sciences. After preparing synthetic samples of the wastewater and determining its turbidity and fecal coliforms concentration, various doses of Chitosan and Potassium Permanganate individually and in combination with each other, were injected to the samples. Afterwards supernatant of jar reactors were investigated for turbidity and fecal coliforms removal. Simultaneous use Chitosan and potassium permanganate has higher removal efficiency than the individual using of them. Highest applied combined dose (3 mg / L Chitosan and 1.5 mg / L potassium permanganate) reduced fecal coliform to a level less than 100 MPN/100mL, which is equivalent 4 log-inactivation of fecal coliforms. Simultaneous use of Chitosan and potassium permanganate in tertiary treatment of wastewater can led to produce lower turbidity, as well as higher microbial quality in the effluent, which can reduce the amount of required disinfectant, consequently disinfection by products formation lowered very much.

This research work was carried out in lab scale using a Jar-test set up. In order to compare the performance of four inorganic coagulants (poly aluminum chloride, ferro sulfate, ferric chloride, aluminum sulfate) in removal of turbidity and color from water, three independent variables (turbidity, color and coagulants dosage) were investigated. The region of exploration for the process was taken as the area enclosed by turbidity (10, 20, 50 NTU), color (5, 10 TCU) and concentration of coagulants (5, 10, 15, 120, 25, 30 mg/l) boundaries. The rapid and slow mixing steps were provided by the rate of 80 rpm for 1 min and 30 rpm for 20 min, respectively. The samples were then remained for 30 min as settling stage. Four parameters including turbidity, electrical conductivity (EC), pH and color were measured from the samples supernatant. Settling characteristics of the flocs formed were descriptively reported as poor, fair, good and excellent. From the results, poly aluminum chloride with concentration of 5 mg/l was found to be the best for the removal of turbidity (99-99.8 %) and color (100 %). However, fine flocs with very good settling velocity was observed at the condition with initial turbidity of 10, 20, 50 NTU. Increase in EC along with decrease in alkalinity was obtained as the coagulants concentrations were increased. The maximum and minimum amount of increase in EC and TDS were resulted from ferric chloride and poly aluminum chloride, respectively.

Paper-recycling wastewaters have high volume and high pollution and its treatment is the most difficult and complicated process because of their colored pollutants and certain rigid chemical structure. In this study, the efficiency of alum in coupled with polyaluminum chloride (PACl) coagulant on the treatment of paper recycling wastewater was investigated. The effects of initial pH, initial COD and coagulation concentration on sludge volume index (SVI), and turbidity and COD removal were studied. Set tested for coagulation process was 2-12 initial pH, 200-2000 mg/l of alum concentration, 50-1500 mg/l of PACl concentration and 250- 2250 mg/l initial COD. According to the data obtained from batch studies, maximum percentage removal of turbidity and COD 89.90% and 85.16% respectively. The SVI of 193 ml/gr was found in this study. This study showed that the alum and PACl coagulants have high ability to remove pollutants from wastewater factory.

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.

The efficiency of particle settling in tube settlers can be improved by reducing tube diameter; however, this has limits due to the clogging at low diameters. In this study, effect of reduced tube diameters on enhanced efficiency of tube settlers was investigated. This improvement was achieved by staging of the operation and reducing tube diameter in the last stage of the multi-stage tube settlers. Theoretical analysis indicated that the efficiency of tube settlers would improve if tube settlers were used in different stages in series and that if their diameter was reduced in the last stage. The predictions from the theoretical analysis were tested in a pilot study. One- and two-stage tube settler pilot plants were used to remove water turbidity caused by clay in the first and second phases of tests with and without adding coagulant, respectively. The tube diameter in the one-stage tube settler were 5.0 cm, and those in those the first and second stages of the two-stage tube settler was 5.0 and 1.2 cm, respectively. The results of both phases showed that the two-stage tube settler was more efficient than the one-stage for turbidity removal with no clogging observed because the majority of the particles had been removed in the first stage.