Efficiency of calcium and magnesium removal by nanofiltration membrane from synthetic water under different operating conditions

There are various techniques for reduction or removal of hardness of water each with its own special advantages and disadvantages. Nanofiltration, process due to its simplicity and efficiently, has gained a great attention and is used for removal of various ions and organic matters. The aim of this study was to investigate the evaluation of efficiency of calcium and magnesium removal by a nanofiltration membrane from synthetic water under different operating conditions. This study was performed in laboratory scale using a commercial NF membrane similar to pilot scale. NF experiments were conducted using a calcium initial concentrations [280, 300, 320, 340 and 360 mg/L] and magnesium initial concentrations [60, 80, 100, 120 and 140 mg/L] with flow rate of 0.4 L/min [Qi] and 0.8 L/min [Q[2]]. To investigate the removal of calcium and magnesium as a function of co-existing anions and cations for NF membrane, sodium, potassium, calcium and magnesium ions [as cation] and chloride, nitrate and sulfate ions [as anion] were chosen. The results revealed that with the increase in initial calcium and magnesium concentration, the removal efficiency decreased, with increasing initial calcium concentration from 280 mg/L to 360 mg/L, the removal efficiency decreased from 69.08% to 61.25%, respectively and magnesium removal efficiency declined from 70.05% to 62.25% with increasing concentration from 60 mg/L to 140 mg/L, respectively. In addition, while flow rate varied from 0.4 L/min to 0.8 L/min, calcium and magnesium removal efficiency descended to approximately 5%. Most effectiveness due to anions and cations with calcium and magnesium were related to sulfate and divalent cations and chloride and sodium lowest effectiveness related to choride anion and sodium cation respectively. According to the results, nanofiltration process was applied as efficient and proper method for hardness [calcium and magnesium] removal from water

Adsorption of reactive red 198 dye on TiO[2] nano-particle from synthetic wastewater

Dyes are one of the most important existing pollutants in textile industrial wastewater. They are often toxic, carcinogenic, teratogenic, and non-biodegradable. Reactive red 198 dye is one of the azo dyes that is currently used in the textile industry. This study was conducted with the aim of investigating on reactive red 198 dye absorption process titanium dioxide nanoparticles from synthetic textile wastewater. This applicable research was performed in a batch reactor on synthetic wastewater with dye concentrations of 100, 150 and 200 mg/L and the effects of parameters such as concentrations of initial dye and TiO[2] nanoparticles, time, and pH[s] on dye absorption efficiency were investigated. The dye concentrations were measured via spectrophotometer [518 nm wavelength]. Results: The RR 198 absorption capacity rates were 92.5, 70, and 37.5 mg/g respectively at pH of 4, 7 and 10 for the initial dye concentration of 100 mg/L and 0.4 g/L absorbent mass at 180 minute. Also dye absorption rates were 51.8, 56.1, and 61.4 mg/g on absorbent respectively for 100, 150, and 200 mg/1 dye concentration, at pH of 4, 1 g/L absorbent mass, and 180 minutes time and the studied dye absorption isotherm was fitted Langmuir model [R[2]=0.98] which was 38.46mg/g for maximum adsorption. The results of absorption studies showed that reactive red 198 absorption/removal rates would increase with increasing the primary dye concentration, reaction time, absorbent mass, and decreasing pH. On the basis of the results, titanium dioxide nanoparticles can absorb reactive red 198 dye appropriately and efficiency of the process is higher in acidic pH. Regarding to TiO[2] application as a photocatalyst in environmental pollutant removal, more pollutant absorption on nanoparticles in acidic condition increases photocatalyst process efficiency

Leachate treatment using wet air oxidation processes

Wet air oxidation [WAO] is one of the advanced oxidation process which reduce organic matter concentration from industrial wastewater, toxic and non biodegradable substances and, solid waste leachate,etc. In this study the efficiency of wet air oxidation method in leachate treatment generating from Esfahan Composting factory was Evaluated. The experiment was carried out by adding 1.5 Lit of pretreated leachate sample the steel reactor with the volume of 3L. The reactor then underwent 10 bar pressure at different temperature [100, 200 and 300 °C] and various retention time [30, 60 and 90 min]. Leachate sample in 18 stages from composting factory in Isfahan in the volume of 20 Lit was taken and the WAO method, was used for pre-treatments. Removal efficiency of COD, BOD, NH4-N, NO3 and TSS were examined. The results showed that the removal efficiency was more than 35% for COD, 38% for BOD, and 85% for TSS within one hour of reaction. The Maximum removal efficiency obtained in this study were 53.3% for NH4-N and 73.9% forNO3-N. the results indicate that the reaction temperatures are the most important factors affecting degradation of organic matter. COD and BODS removal efficiency by WAO process increased as the time of reaction went up. In addition, BOD5/COD ratios of the effluents, which are generally regarded as an important index of biodegradability of leachate sample, were determined and improved grately as it reached to 84%. The WAO process presented in this paper is considered an efficient process for pretreatment of leachate, as the COD, BOD5 and NO3 reduction observed in leachate samples

[Comparisons of three advanced oxidation processes in organic matter removal from Esfahan composting factory leachate]

Wet air oxidation [WAO] is one of the advanced oxidation process which is mostly used to reduce organic matter concentration from industrial wastewater, toxic and non biodegradable substance and solid waste leachate. The objective of this paper is comparisons of three advance oxidation in organic matter removal in different conditions from Esfahan composing factory leachate. The experiment was carried out by adding 1.5 Lit pretreated leachate sample to 3Lit autoclave reactor and adding 10 bar pressure at temperature of 100, 200 and 300 °C and pressure [10 bars] with retention time of 30, 60 and 90 min. leachate sample in 18 stages from composting factory in Isfahan in the volume of 20 lit was taken and the three methods WAO, WPO, and a combination of WAO/GAC were used for pre-treatments. Pure oxygen and 30% hydrogen peroxide was used as oxidation agent. The result shows significant improvement on the removal rate of COD [7.8-33.3%], BOD5 [14.7-50.6%] by WAO process. The removal efficiency of 4.6-34% COD, 24-50% BOD, was observed in the reactor. Adding the GAC to the reactor improved removal efficiency of all parameters. Combination Process [WAO/GAC] removed 48% of COD, 31-43.6% of BOD. Combination process demonstrated higher efficiency than two other previous methods as BOD5/COD ratio of 90% achieved. The WAO process presented in this paper is efficient for pretreatment of leachate, And the modified WPO process remove organic materials and ammonia moreover WAO/GAC can be considered as an excellent alternative treatment for removing reluctant organic matter [COD, BOD5] and organic nitrogen compounds, which found in leachate

[Ability of iron oxide nanoparticles in ion silver removal from synthetic wastewater]

Ion silver from the internal surfaces tubes and generators inter to industrial wastewater by corrosion process. These ions have harmful effects on plants, animals and humans. Iron oxide is commonly used to removal chemical contaminates. However, the used of nanoparticles in removing pollutants is more effective than the mass. In this study, using of iron oxide nanoparticles for removal silver ions from synthetic industrial wastewater was investigated and the effective parameters were optimized for the better removal. This study is a experimental-laboratory that iron oxide nanoparticles was synthesized by exposing nZVI into air and then Ag+removal efficiency was studied in batch system. Also, the impact of the important field parameters including pH, iron oxide nanoparticles concentration, retention time, and temperature were investigated. After centrifugation and filtration, the amount of ion silver was determinate by flame atomic absorption. The results of this research showed that iron oxide particles were reacted with Ag+in nano scale. The maximum removal at pH=3, nano iron oxide concentration 35 g L-1 and 25°C was 99.2%.In optimum condition [pH=3, nano iron oxide concentration 10 g L-1, 5 hours reaction time and 25°C temperature] 87% of Ag+was removed. The concentration of nano iron oxide and pH had significant effect on the Ag+removal. The results showed that Ag+removal in acidic pH controlled by absorption on surface then reduction by atomic core. While, removal in basic pH controlled by absorption. The studies showed that iron oxide nanoparticles have high ability to remove Ag+and decrease of chemical pollution of Ag+from industrial wastewater

[Study of eggshell performance as a natural sorbent for the removal of reactive red 198 dye from aqueous solution]

Dye compounds is one of the most critical contaminant for natural ecosystems. The aim of this study were to determine the primary concentrations of reactive red 198 dye [RR 198], adsorbent dosage and pH influences for the adsorption of RR 198 onto chicken's eggshell [ES] as an adsorbent. The target adsorbent was prepared in laboratory conditions and pulverized by ASTM standard sieves. Surface characteristics and measurement of the adsorbent surface area was carried out with Scanning electronic microscope [SEM] and via N2 gas adsorption with Brunauer-Emmett-Teller isotherm. The maximum absorption wave length of this dye [lamda-max] was determined by spectrophotometer [Optima SP-3000 Plus]. Analysis of absorption spectra showed that the lamda-max of RR198 is 518 nm. The results show the Calcium components are the main constituent of ES with 1.2 m[2]/g. Elevation of the ES dose [2 to3 g] lead to increasing of dye removal from 80% to 92%. The results show that elevation of pH from 4 to 10 would lead to increasing of RR 198 adsorption from 44% to 64% but increasing of preliminary dye concentration would lead to decreasing of dye adsorption from 72% to 23%. The kinetic studies revealed that the adsorption of RR 198 is rapid and complying with second-order kinetic [R2=0.995] which the kinetic constant is 0.0004min-1. Eggshell is a cheap adsorbent that can be used for the removal of dye components from alkaline solutions

Removal of methylene blue dye from textile simulated sample using tubular reactor and TiO[2]/UV-C photocatalytic process

In this study, photocatalytic degradation of methylene blue was examined using different concentrations of TiO[2] nano-particles [diameters less than 21 nm] and ultraviolet [UV-C] radiation in a tubular reactor. Different concentrations of catalyst [0.3-1.2 g/L], different pH conditions [3, 7 and 9] and dye concentration [15, 30 and 60 mg/L] as well as sample rotation level [125 mL/min] were studied. The sample passed 1-7 times through the quartz reactor exposed to UV-C ray [constant intensity = 2.8 mW/cm[2]] [every rotation time was 8 min]. Results of this research showed clearly that methylene blue is significantly degradable by TiO[2] and UV-C radiation. Increasing dye concentration resulted in decreased efficiency and thus, as more samples passed through quarts tube, removal efficiency increased. Methylene blue with concentration of 15 mg/L and after 7 rotations in the reactor [56 min] was removed with the efficiency of 98%. Subsequent to dye removal, 47% of initial COD decreased simultaneously

Equilibrium and kinetics study of reactive red 123 dye removal from aqueous solution by adsorption on eggshell

The aim of this study was to determine the equilibrium and kinetics adsorption of reactive red 123 dye [RR 123] from aqueous solution with chicken's eggshell as an adsorbent. The initial concentrations of reactive red 123 dye were selected in the range of 25 and 50 mg/L. The target adsorbent was prepared in laboratory conditions and pulverized by ASTM standard sieves. Measurement of the adsorbent surface area was carried out via Brunauer Emmett-Teller isotherm. The experimental data were analyzed with Langmuir, Freundlich and Temkin isotherm models. The results showed that the calcium components were the main constituents of eggshell [around 95% Ca]. The experimental adsorption isotherm was in good concordance with Langmuir and Freundlich models [R[2]>0.90] and based on the Langmuir isotherm the maximum amount of adsorption [q[max]] was 1.26 mg/g. Increase of the eggshell dose and the solution temperature beyond 45 Degree C led to decrease of the adsorbed dye per mass unit of the adsorbent, but increase of the solution pH up to 9 led to the improvement of dye adsorption. The kinetic studies revealed that the adsorption of reactive red 123 was rapid and complied with pseudo-second order kinetic [R[2]= 0.99], with the kinetic constant of 0.02 g/mg.min

[Application of solar irradiation / K2S2O8 photochemical oxidation process for the removal of reactive blue 19 dye from aqueous solutions]

Dyes are organic compounds with complex structures, which due to toxicity, carcinogenicity and nonbiodegradabity, this type of pollutants is one of the most important pollutants of the environment. The goal of this research was to study the feasibility of the application of solar irradiation in presence of potassium persulfate [K[2]S[2]O8] for the removal of Reactive blue19 [RB19] from synthetic wastewater. This research was carried out in laboratory scale with using of 200ml volume of batch photoreactor. The effects of operating parameters such as concentration of K[2]S[2]O[8], pH, photo exposure time and preliminary concentrations of dye on decolonization have been evaluated. Different concentrations of pollutant in waste water were prepared by solution of variousmasses of RB19 on tap water. The reactors were exposed with natural solar irradiation as a UVA source from11 am to 14 pm. The maximum absorption wave length of this dye [lambda[max]] was determined by spectrophotometer [Unico, 2100]. The measurement of dye concentrations was determined with using of standard curve and its best line equation Analysis of absorbtion spectra showed that the lambda[max] of RB19 is 592 nm. The average intensity of the UVA irradiated from solar system was 54.6 microW/Cm2. The results of decolorization process showed that 38.2%of this dye can be removed within 3 hr in the presence of potassium persulfate and decreasing of pH leads to the elevation of dye removal efficiency. Based on these findings, the efficiency of dye removal with 3h photo exposure time and pH ranges of 4,6 and 8 were found to be 98.2 88.5 and 78.5%, respectively. Also, the results showed that increasing of K[2]S[2]O[8] dosage leads to elevation of dye removal efficiency in 3h photo exposure time and K[2]S[2]O[8] dosages within 1-5mmol/L, with the removal efficiency of 75,86,92,95 and 98.5%, respectively. Analysis of data indicates that the kinetic of the removal of RB19 with this process is a first order reaction which its rate constant is 0.01min-1. Due to the operation problems presented in heterogeneous photocatalitical processes such as catalysts separation and high costs of operation and maintenance of these processes caused by manmade sources of irradiations; homogeneous photocatalitical process with using of potassium persulfate associated with natural solar irradiation can be used as a suitable process for the removal of dyes from textile industries wastewaters

Application of ozonation on the removal of reactive red 198 dye at alkaline condition

Dyes are the most important pollutants of textile industries which have complex structures as well as toxic, carcinogenic, teratogenic and nonbiodegredable properties. This research was performed to compare the efficacy of removal and mineralization of Reactive Red 198 dye at alkaline and neutral pH. The effect of different pH: 7,9,10 and 11 in dye and COD removal from 250 mg/1 aqueous solution of RR198 was evaluated. Dye removal efficiency was measured by UV-vis spectrophotometer and data were analyzed using SPSS 16, via statistical tests including One-Way ANOVA. COD removal efficiency was also measured by closed reflex method. Dye removal efficiency was higher than 96% in all different types of pH and also showed significant difference in different time intervals [P<0.05]. COD removal was lower than dye removal and in different types of pH: 7, 9, 10 and 11 which after 60 minutes of reaction reached to 31, 40, 43 and 53% respectively. From the collected data it is obvious that rapid dye removal is due to the reaction of both molecular ozone and free radicals with dye molecules but more COD was removed only after the generation of hydroxyl radicals via pH elevation

survey on the relation between satus of the environmental health and health of the carpet workers in rural of Mehriz-Yazd Iran [2007]

Carpet industry is one of the most important traditional handicraft in IRAN. Considering the long history of carpet industry in Iran and the existence of working a lot of men and women in the villages of Iran in this field, carpet industry as can be regarded a complementary industry for farming so paying attention to the health of worekers in the field can play an important role in socio economic development of our villages. This descriptive cross- sectional study was conducted on 2200 carpet handicrafters in Mehryz, Yazd, Iran, selected through census. The relevant questionnaire was filled out by occupational health specialists and intern students of medicine via inspection, clinical examination and interviewing. Results:44.4% of the target group were between 15-24 years of age. 78.5% of the married subjects had 5 children or lower and 85.2% of them had different levels of literacy. 14.7% had a history of psychologic disorders; 4.6% ophthalmologic disorders, 4.5% endocrine disorders and 19.8% had history of infectious diseases. Results: indicated that there was a significant relationship between different disorders of mind, skin, heart, muscle, and skeleton with temperature of the mind, handicrafters working environment [P<0.05]. As we expected pulmonary disease was less prevalent among the subjects who possessed a better and more appropriate ventilating system for their morking place after correlation analysis, of the data it was revealed that with increasing the working years, the subjects' visual capacity also decreased. In addition, the working hours decreased in relation to the subjects' increase in blood pressure. The result of the study showed that some diseases like pulmonary and ocular diseases is high in carpet workers.The diseases in the subjects with inappropriate working place was higher than others. So it is nesseary today more attention to health of the carpet workers and their working places

Application of iron impregnated activated carbon for removal of arsenic from water

The presence of arsenic in drinking water is one of the greatest threats to public health. The aim of this experimental investigation was to study the removal efficiency of As [v] from water by application of iron-impregnated activated carbon [Fe-AC]. Coating of activated carbon with iron salt was carried out by impregnation method and thermo-chemical reactions with using of 100 mM FeCl3 solution. The Fe-AC was pulverized using ASTM standard sieves with the range of 16-20 mesh. The solid structure and surface characteristics of Fe-AC were determined using conventional techniques. Batch adsorption experiments were carried out with 300 and 600 micro Lig/L arsenate. Langmuir, Freundlich and Dubinin-Radushkevich models were used to describe the isotherm and energy of adsorption. The results of this study showed that 2.5 h contact time was enough to achieve the equilibrium. The adsorption of As [v] had a good compliance with Langmuir model [R[2]= 0.995] and the maximum adsorption capacity was obtained as 0.024 mg/g. The results of kinetic studies showed that As[v] adsorption on Fe-AC may be limited by film diffusion step [m=0.26]. The mean free energy of adsorption [E] calculated from Dubinin-Radushkevich isotherm was found to be 1.52 kj/mol which implies that the adsorption of As[v] on Fe-AC is a physical adsorption. The results indicated that Fe-AC is one of the suitable adsorbents which can be used for the treatment of arsenic contaminated waters

Study of the effeciency of volcanic rock bed filters in enhanced ammonia and fecal coliform removal from khoy wastewater treatment plant

Ammonia and fecal coliform removal from wastewater is of high necessity because of its inappropriate impact on environment where wastewater accumulates. Aerated lagoons as well as polishing ponds would not be able to decrease ammonia and fecal coliforms in an efficient way. Different procedures are usually applied for the removal of ammonia and fecal coliform in wastewater treatment plants. In this study, effluent of polishing pond in wastewater treatment plant of Khoy in North-West Azerbaijan with three different loading flow rates [0.3, 0.6, 0.9 m[3]/m[3].d] was entered into the rock filter with volcanic rock bed, rock diameter size of which was 50 mm. To determine the efficiency of rock filter in any loading flow rates, 10 samples of influent and effluent were taken. The results showed that mean of effluent ammonia level changed from 16.8 to 4.8 mg/1 and effluent fecal coliform from 1.9xl0[4] MPN/l00ml to SJxl0[3] MPN/lOOml. Rock filter efficiency for Ammonia and fecal coliform removal of pond effluent were 71.4% and 70% respectively. Ammonia and fecal coliform decreased in all loading flow rates but in the first rate changes were more remarkable than the two other rates. As loading flow rate increased, removal efficiency decreased. This is probably due to low hydraulic retention time that resulted in decreasing nitrification. Thus it is concluded that rock filter here presented has better efficiency than what were used in similar studies

Survey of corrosion and precipitation potential in dual water distribution system in kharanagh district of yazd province

Corrosion and precipitation in drinking and sanitary water in distribution systems leads to economic and health damages. The goal of this study was to survey the chemical quality of water in Kharanagh ward in Yazd province and to predict the potential of corrosion and precipitation in these waters. For determining the chemical quality of water, some cross-sectional samples with 2-4L of water volume were taken. All of the samples were collected, stored and preserved in glass or polyethylene containers and were analyzed based on standard methods. The potential of corrosion and precipitation in waters was calculated by Langelier Saturation Index [LSI], Risnar Index [RI] and decision was made based on calcium carbonate resistance. Based on the values of LSI, drinking and sanitary waters showed precipitative properties. Based on RI, the waters showed a corrosive quality from the point of corrosion and precipitation potential. Based on calcium carbonate resistance parameter, the waters had precipitative quality. The chemical quality of water in Kharanagh district is non-balanced that leads to precipitation in water distribution and other equipments thus planning water quality stabilization for the elimination of economics damages is necessary

Gamma background radiation in Yazd province, a preliminary report

There are relatively rich uranium mines in regions of Saghand and Bafgh in Yazd province. This survey was carried out to provide a map of ambient gamma radiation of Yazd province and the probable effects of the existence of these mines on background radiation dose rates. The measurements of the outdoor and indoor-environmental exposures [including cosmic and terrestrial components] were accomplished by a portable Geiger Muller detector in the five areas in each of eight big cities of Yazd province. The average exposure rates of indoor and outdoor ambient of Yazd province were 13.9 +/- 0.7 microRh[-1] and 11.6 +/- 0.8 microRh-1 respectively. The average dose rates in air, resulting from gamma background radiation of indoor and outdoor were 122 +/- 6.8 nSvh[-1] and 101.4 +/- 7.4 nSvh[-1] respectively. The annual average of equivalent dose in air was found to be 1.03 +/- 0.05 mSv, and the annual average of effective dose was 0.72 mSv. The results of this study in comparison with the same measurements in some other cities in Iran such as Isfahan and Tabriz, proves that the existence of uranium mines doesn't affect gamma background radiation of Yazd province