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Mineral anions are among the most important toxic substances harmful to humans and animals even in low concentrations. Nitrate ions are considered important surface and groundwater pollutants for their high solubility in water. Nitrate is converted to nitrite and N-nitroso in the human body through certain reactions. N-nitroso combinations are considered carcinogenic and the primary cause of methemoglobinemia diseases. The existing nitrate in water resources is not easily separated for it is highly soluble and therefore the methods usually used for this purpose are very costly. Various methods can be used to remove or reduce the concentration of nitrate. Reverse osmosis, electrodialysis, electrocoagulation, ion exchange, and membrane processes are among the physicochemical methods of nitrate purification. Among the types of nitrate purification methods, biological processes with relatively high efficiency, the possibility of complete removal of the pollutant, and less harmful effects on the environment, are some of the most suitable options for the decomposition and removal of nitrate from water and groundwater. In a situation where the contaminated area is wide and it is not possible to pump water due to economic reasons or the large volume, treatment using in-situ methods will be a more suitable option. One of the types of in-situ biological treatment processes is the use of the permeable reactive bio-barrier (PRBB) method. PRBB is one of the novel and reliable methods used for in-situ groundwater remediation.  A PRBB is an emplacement of reactive media in the sub-surface designed to intercept a contaminated plume, provide a flow path through the reactive media, and transform the contaminant(s) into environmentally acceptable forms to attain remediation concentration goals down the gradient of the barrier. PRBB can degrade nitrate at a high rate under anaerobic conditions. In this research, different concentrations of four chemical substances including ZVI, nZVI, NaS2O3, and Na2S2O5 were used as Oxygen Capturing Compounds (OCC) in the removal of nitrate from polluted water in the PRBB process on a laboratory scale. Based on the obtained results, these substances affect the parameters of DO, pH, MLSS, turbidity, nitrate concentration, durability of DO, and ORP. After laboratory tests and taking into the opinion of experts, the qualitative effect of each parameter was calculated quantitatively and through the analytical hierarchy process (AHP), the best oxygen-capturing compound was selected. The results obtained from AHP (with an inconsistency ratio of 0.063), revealed that the priority of choosing OCC from three technical, economic, and environmental aspects is related to the concentrations of 750 mg/l ZVI, 240 mg/l Na2S2O3, 85 mg/l Na2S2O5 and 550 mg/l nZVI respectively. The concentration of 750 mg/l ZVI (the best OCC) during the experiments was able to reduce the DO from 7 to 0.05 mg/l in approximately 500 minutes and within the ideal range of the denitrification process (DO<0.05 mg/l). In addition, after the durability of DO tests, it was found that this substance has maintained its deoxygenation properties for longer than other used compounds. Also, based on the results, the concentration of 750 mg/l ZVI had a positive effect on the increase of MLSS and removal of nitrate. 

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Mnemiopsis leidyi population activities first were recorded during the coastal observations in 2001 in which its population considerably increased afterward and now sustained the southern Caspian Sea. Maximum summer-autumn M. leidyi abundance was recorded in euphotic layer in 2002 (851±85 ind.m^-3) and maximum biomass was in 2001 with 48.1±14.4 g.m^-3) while minimum were in aphotic layer. In years 2003 to 2011, M. leidyi abundance and biomass sharply declined to 1-843 ind.m^-3 and 0.07-37.7 g.m^-3, respectively. The length-frequency distribution of Mnemiopsis showed larval, juveniles and transitional stages that made up 98.6% of the total population. In the southern Caspian Sea, Acartia tonsa was the highest number of mesozooplankton species (36 species) which decreased tenfold after Mnemiopsis invasion during 2001-2010. Fecundity experiments of Mnemiopsis showed the average of 8 eggs. day^-1, with a maximum of 35 eggs.day^-1which increased with increasing body length. The main food was larger amounts of zooplankton prey such as copepodites and adult of A. tonsa. It seems the sharp decreased of Mnemiopsis abundance could be related the decreasing of ova reproduction; and food ability is the main reasons of M. leidyi sustained in the southern Caspian Sea. The objective of present study was to provide information about parameters influencingthe M. leidyi decreased after initial bloom invasion in the southern Caspian Sea.

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Urban space is combination of two parts including form and meaning. The signs in the urban space together with its codes form the part of urban space meaning. Signs are the part of the visual media which are presented for the citizens, So the citizens discover code's meaning by decoding of internal concept and are influenced by it. The question is that the signs which are presented to citizens as a visual media what relations they have with national identity elements? Urban signs can have meanings of national identity elements into their codes. It is notable that prominence of some elements and factors rather than others has role in formation, reinforcement and representation of national identity. Therefore in this research an attempt has been made to evaluation of relations between the signs meaning in urban space and elements of national identity factors in the 6th, mural district of Tehran as a case study by using of qualitative analysis and the basics semiotics. The results of this research in the 6th district of Tehran indicated that urban signs are influenced by national identity factors and they have meanings and concepts of it inside themselves. Also prominences of some national identity features rather than other features lead to formation of national identity and also play the important role in reinforcement and representation of national identity by repeating the meanings influenced by national identity.

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The purpose of this study was to investigate the effect of strategic uncertainty on the business strategy through price, product, promotion, and location compatibility In Selected companies producing sports equipment. The research method is applied in terms of purpose and collecting data, a descriptive survey based on structural equation modeling. The statistical population of the present study was selected productive sport facilities companies' staff. The data collection tool was a standard questionnaire. To assess the validity of the questionnaire, divergent validity tests and convergent validity was used in Smart Pls software. Also, Cronbach's alpha test was used to determine the reliability of the questionnaire; The research findings indicate that strategic uncertainty has a significant effect on the business strategy through price, product, promotion, and location adjustment (P-value = 0.05). Therefore, companies producing sports equipment can develop their business by using strategic uncertainty of techniques such as price adjustment, product adjustment, promotion adjustment, and location adjustment.

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"Rokub Al Kawsaj"or no beard man backing up, is a celebration, which was hold to exclaim farewell to winter and arrival of spring. "Sarvato Bost", or kāshmar cypress, is a tree, which has been by Zoroaster from Paradise in Predecessors’ belief, and planted in kāshmar by himself or by Garshāsb. Since the cypress tree was sacred in the eyes of Iranians, they respect this ancient tree. Kāshmar cypress was proud of Xorāsān people until the Mutawakkil Abbāsi era, until it was cutt off by the order of the Caliph. Abu Mansur Saʼālebi; this  has been mentioned in "Simār al qolub fil mozāf wal mansub" to "Rokub Al Kawsaj" and "Sarvato Bost" by two examples in the mentioned book. We intended to affirm Even these books in Arabic heritage, which apparently has no relation with Iran history, can encompass valuable subjects. .

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The beet moth, Scrobipalpa ocellatella (Boyd) (Lepidoptera: Gelechiidae) is one of the most destructive pests of beet. The insect overwinters as larvae of different instars in beets which are left in the field. Supercooling point (SCP) of individual larvae showed broad range variation from -6 to -25 °C. In the present study, factors affecting the broad range of SCP were investigated. Larvae showed a great increase in SCP when they were induced by exogenous ice nucleation. Defensive oral discharge (DOD) decreased SCP but it had no significant effect on supercooling ability of larvae. The presence of sufficient food in guts of field collected larvae induced an increase in SCP. Therefore it could be concluded that surface moisture and food particles in the gut may act as ice nucleating agents (INAs) that cause freezing of the body fluids at higher temperatures. Furthermore, second and third instar larvae, owing to their small size, had greater capacity to supercool in comparison to fifth feeding instars. Broad range in SCPs might be due to diversity in overwintering larvae which have different capacity for supercooling.

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Introduction
Spatial court in the city, management, distribution and distribution of space services and urban possibilities, special attention e-mail. In the discussion of equality and equality, none of the urban groups and classes of residents have a tendency to oppose each other and they provide equal treatment for everyone, regardless of social and economic status, for access to general urban services. For this reason, this topic, as it prevents the accumulation of possibilities and urban services in one area, the polarization of the city space and social inequalities, it makes access to the possibilities in the city for everyone. In accordance with this, the present research is aimed at assessing the spatial justice in the distribution of services and urban possibilities in the palaces of eight Shahr, Tehran.
Methodology
The research method is descriptive-analytical and based on library and documentation methods. The data used in this research are the data that have been extracted from urban areas. In order to analyze the information, in the first stage, using the entropy scale, balance (equality) or disequilibrium (inequality), each of the uses has been analyzed and then proceeded to rank the 13 palaces, regions. And the level of utilization of urban services and possibilities using the Cocoso model has been used for ranking the regions
Result and discussion
Since the globalization of cities and the urbanization of the world is the most prominent feature of the twenty-first century. Especially fortunately, the growth of urbanization in the majority of cities in the developing countries is more rapid. Various (housing, traffic, pollution, urban identity, commercial land, unsustainable land use, etc.) have been faced.
Land, as a limited, scarce and non-renewable commodity, in the face of rapid urban development and increasing collective demand, is transformed into an expensive and profitable commodity, as a result of which it is considered as a means of commerce for the purpose of securing profit and general welfare and improving the standard of living. Special groups are declared and cause many social, economic and environmental problems.
Based on these problems and difficulties of the current urbanization in this research with a radical and critical approach based on theories related to justice and spatial equality, after identifying and analyzing urban land use conditions, types and programs derived from them, the percentage of their realization. Reasons and forces influencing their realization or non-realization, as well as the space produced, the positive or negative spatial-spatial effects resulting from them. Perhaps the most important concern that prompted me to address this matter is the chaotic and confused situation in the suburbs of the three districts and the palaces of the third district of the eight city of Tehran in recent years.
The conditions are not improving, they are getting worse day by day. The situation of overcrowding and non-distribution of inappropriate uses, which have arisen due to major reasons, have led this region to a state of chaos. The urban land has been transformed into a bubble with the expansion of the stock market, the dimensions of which are getting bigger and bigger every day. Since the use of urban land is the core of urban planning, based on this assumption, it is possible to understand the root problems and spatial problems of the current urban area.
Conclusion
The results obtained indicate the imbalance in the distribution of spatial services and urban possibilities. Based on the results of the entropy method, cultural quality with a weight of 0.463 has won the first rank. Sports quality with a weight of 0.255 has won the second rank and green space quality with a weight of 0.153 has won the third rank. According to the Cocoso  model and according to the results, Kerman district has won the first rank, Fadak has won the second rank and Wahidiya has won the third rank. Therefore, the eastern region and its palaces, which are located in District 1 and part of District Two, are in a better condition than the western region, where the palaces of District Three are located.

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An organization requires careful planning in human resources for its optimal use of human resource. One of the variables affecting HRP is turnover intention. The purpose of this research is planning human resource with emphasis on the influence of moral texture on female employees' turnover intention in a university. This research also examines the role of work values as a moderator variable. Research analysis is based on gathered data from a random sample of two-stage classification. The samples of 210 subjects were determined by Morgan table. For data analysis, ANOVAs test, confirmatory factor analysis and structural equation by using WARPPLS software has used. The results of the interviews show that despite high turnover intention of the organization, staff refused to do so for the reasons such as lack of better alternative jobs outside the organization and also benefiting from public employment. Another finding indicates that the intention of turnover among female faculty members was greater. The results also show that the perception of ethical context has a meaningful effect on turnover intention and moderator role of work value was significant for leaving the organization. However, the relationship and reward value has more effective role on the relationship between ethical context and turnover intention.
 

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The present research is aimed to evaluate the working memory (WM) in Persian words (as a L2) in comparison to it in Chinese words (as L1) in Chinese Persian learners. Thirty learners at Dehkhoda institute were chosen as the study sample. Sampling has been relied on the available subjects who took part in the visual n-back task which was specifically designed to measure WM. The participants had to press the congruent key (predetermined number 1) if the stimulus was the same as the one presented just before, and pressed incongruent key (number 2) if it was not. Then they took part in the stroop test. In psychology, the Stroop effect is a demonstration of interference in the reaction time of a task. the stroop test here included 40 stimuli- a pseudorandom selection of 20 Persian words and 20 Chinese words, selected among four main color which was written with incongruent ink. The participants had to press the key predetermined the color of the word- not ink-. Accordingly, the score of their WM “accuracy”, WM “mean respond time”, attention bias “accuracy” and attention bias “mean respond time” have been calculated separately for both languages and compared with paired samples T test. Results illustrate a meaningful difference between L1 and L2 among the selective attention mean respond time, WM accuracy and WM mean respond time, and didn’t illustrate meaningful diference between L1 and L2 among selective attention accuracy.

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Chitin and chitosan are two very important biopolymer products that have so many usages in the high cost industries. Chitin Converts into chitosan via de-acetylation of chitin. It occurs by alkaline melting method in the absence of oxygen. Chemical structure change, severe environmental pollution and De-polymerization are of the major problems in producing high quality chitosan. In this study for conversion of chitin into chitosan fungus Aspergillus niger strains (ATHUM-10864), the generator of de-acetylases enzymes were used instead of chemicals. Chitosan quality was determined via elemental analysis infrared spectroscopy, X-ray tomography, molecular weight determination and estimation of crystallinity percent, color and molecular structure.The results showed 80±5% efficiency in the conversion of chitin into chitosan or de-acetylation degree of chitin. The gained chitosan contained of 44.4 % carbon, 8.9 % nitrogen, 2.7 % hydrogen and 39.5 % oxygen. The physical characteristics were as 94.5% Crystallinity and pale brown color. The chemical structure of per unit of chitosan was obtained as C6H12NO4. The results showed that replacing biological methods instead of chemicals was possible to access well quality products. It also eliminates the use of chemical materials such as concentrate sodium hydroxide that is damaging the environment.

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The oath has long been manifested in culture and literature in a variety of ways. In this study, the patterns of swearing in Bakhtiari people is analyzed. Oaths of fire, fire stoves, blades of sun, running water, bread, nuns, temples, devotees, underworlds, and thugs are the most important examples of swearing among the people of Bakhtiari. The importance of taking an oath to this people is the last way to prove the truth of the word and to distinguish the righteous from the wrongdoer. In this study, while studying the types of oaths in Bakhtiari people, the literary characters and their mythological aspects are investigated as well. This research is fundamentally based on the field-based library study and qualitative content analysis. After examining various sources and analyzing the literary and mythological aspects of swearing among the Bakhtiari people, it can be said that the ritual is a remnant of the same ritual in ancient Iran. Also, the oaths of fire, bread and salt, time, running water, sun and souls of the beloved ones are among the most important and common manifestations of oath taking among these people that have many literary and mythological aspects. The function of oath is to prove the truth of the word and recognize the true from false.
 

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Aims: The increasing development of microalgae applications has led to the concentration of new multidisciplinary studies to facilitate commercial cultivation of these organisms due to cost reduction and productivity enhancement. The aim of this study was the growth and quality optimization of Spirulina biomass by changing the dilution of medium and using the aeration cycle.
Materials and Methods: In this experimental study, the effect of concentration of Zarrouk medium (0 to 100% dilution) and aeration cycle on specific growth rate and dry weight, as well as the content of chlorophyll and carotenoids of Spirulina were investigated, using response surface method, central design. A total duration of 16 hours was aerated in any 24-hour period; the interval time between these aerated periods varied between 1 to 8 hours. The data were analyzed by SPSS 16 software, using multiple regression test.
Findings: The highest biomass (0.659mg/ml) was obtained at 80% concentration of culture media and aeration cycle of 2.75 hours and the highest specific growth rate (0.230 daily) was obtained at 60% concentration and aeration cycle of 4.5 hours. The highest aeration cycle (8 hours) resulted in a significant and simultaneous increase in the content of chlorophyll and carotenoids (11.65 and 2.67 mg/g, respectively).
Conclusion: The growth and quality optimization of Spirulina biomass can be accomplished by changing the dilution of the medium and using the aeration cycle.

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There are known techniques for cyanide remediation from contaminated soil such as soil washing, soil oxidation and biological degradation. However, there is very little research for electrokinetic remediation of cyanide from soil. This study investigates the application of electrokinetic remediation to contaminated soil with high clay content and low coefficient of permeability. The experiments were conducted with two electrodes as cathode and anode poles, which were placed inside the soil using the direct electrical current. Thus cyanide ions were transported to the anode pole and caused the remediation of the soil. The contaminated soil from tailing dam of Takab gold processing plant was used. Contaminated soil with the concentration of 420 mg/kg, distilled water and NaOH were employed in the electrokinetic cell. The experiments were conducted on the optimum moisture content of clayed soil at two voltage gradients (1.0 and 1.5 VDC/cm for the duration of 7 and 14 days) in order to assess the effect of voltage gradient when employing 1M NaOH solutions and distilled water at the anode pole. For each test, cyanide removal efficiency, the pH of the soil, moisture content, electrical conductivity and the electrical current and flow were determined. The measurements were conducted for the entire duration of electrokinetic experiments and at the end of the test. The results indicated that the cyanide removal obtained in 7 and 14 days was approximately 65% and 80%, respectively. The results also showed the pH of the soil was changed from 8.83 to 1-2 for the anode and to 12-13 for the cathode pole. The cyanide transported to the cathode and the pH were the most important dominant factors for cyanide remediation.

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Aims: Any surgery could be an anxiety-provoking event. A high level of preoperative anxiety may change the result of surgery. This study aimed to determine the effects of training intervention on anxiety in patients undergoing knee replacement.
Materials & Methods: This quasi-experimental study was conducted on 90 patients who were candidates for knee joint replacement surgery in teaching hospitals of Bojnord city in North khorasan Province in 2021. Patients were enrolled in three 90-minute sessions. In the first two sessions, the surgeon informed the patients about the disease, treatment approaches, surgery, and anesthesia, and in the last session, the clinical psychologist instructed them on how to control and deal with anxiety. Anxiety was assessed before, immediately after the intervention, and one day before surgery.
Findings: The mean scores of state anxiety before, immediately after the intervention, and one day before surgery were 44.38±10.76, 41.49±9.41, and 36.19±6.40, respectively. Moreover, the mean scores of trait anxiety before, immediately after the intervention, and one day before surgery were 43.87±10.81, 41.27±8.39, and 38.83±6.56, respectively, which show the effectiveness of the intervention in controlling patients' anxiety (p<0.05).
Conclusion: Informing the patients about their disease and how to deal with it and giving awareness about the effectiveness of the operation by the surgeon and the clinical psychologist is effective in controlling and reducing anxiety.

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Abstract: Two kinds of concrete sealers including epoxy and waterproof were used to immobilize TiO2 nano-particles on concrete surfaces for treating 25-500 mg/L synthetic phenolic wastewater using photocatalytic process. The reactor consisted of contaminated tank, photocatalytic and aeration zones. Irradiation of TiO2 was performed by UV-A lamps at different intensity (4.42- 8.9 mW.cm-2) placed 10 cm above the concrete surfaces. SEM and EDX analys is showed a uniform appearance of TiO2 catalyst on the concrete. In influent phenol concentration (100 mg/L), pH=7 and retention time (4 hr), the removal efficiency by epoxy sealer was more than 20% compared to the waterproof sealer because of hydrophobic effects. Reduction of removal efficiency was less than 2% for the epoxy sealer after several iterations of the process. Finally, the effects of intensity and wavelength of UV lamp and system pH in removal efficiency were evaluated.

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Abstract: Dyes and pigments are the major and important groups of chemical compounds with high amount of production and consumption amongst various environmental pollutants. For example, the annual imported amount of dye is over 7000 tons in Iran. Most of the dyes used in textile industries are considered either as inert or non-toxic, although some are not totally innocuous. The important fact is that most of them are made of carcinogenic chemicals that may be reformed as a result of metabolism. More than 50 percent of dyes consumed in different processes are discharged to wastewater, which in addition to changing the color of water, are preventing light penetration into the water and photosynthetic function that leads to destruction of aquatic ecosystem and some aquatic species. In recent years, increasing production and use of synthetic dyes, which have more complex structure and chemical stability as compared to natural dyes, more attention has been paid to their environmental pollution and importance of their treatment. Biological treatment is often the most economical alternative as compared to the physical and chemical treatment processes. But as most of dyes are hardly biodegradable, biological systems donot have capabilities in their removal. In expensive chemical processes, unexpected by- products and sludge are the main disadvantages. So, application of physical methods is preferred to control these kinds of pollutions. Different physical methods are also widely used, such as membrane–filtration processes and adsorption techniques. Adsorption is one of the most popular, flexible and effective methods that provides an attractive alternative for the treatment of colored water, especially if the sorbent is inexpensive and does not require an additional pre-treatment step before its application. It also does not result in the formation of harmful substances. Based on the aforementioned reasons, two adsorbents of sawdust and bentonite clay (absorbent aluminium phyllosilicate) were applied for the removal of cationic astrazon blue (F2RL) dye from wastewater regarding the two main factors of cost and availability in Iran, especially in the central provinces of the country. The parameters of pH, dye concentration and contact time were studied in this research. According to the study results, the optimum pH of 7 was found for the removal of dye for both sawdust and bentonite. Data analysis showed that increasing of the initial dye concentration resulted in the decreasing of removal efficiency. The maximum efficiency for the removal of dye from the solutions with the initial concentration of 25, 50 & 100 mg/L was 96.75, 91.11 & 79.26 percent for sawdust and 97.32, 96.78 & 94.62 percent for bentonite, respectively. The equilibrium time was 240 and 90 minutes for sawdust and bentonite, respectively. For the effect of adsorbent dosage on the removal of dye, experiments were carried out with two initial dye concentrations of 50 & 100 mg/L. By increasing of the adsorbent dosage, the maximum efficiency for the removal of dye from the solutions with the initial concentration of 50 and 100 mg/L increased from 53.46 to 97.06 percent and 49.76 to 96.83 percent, respectively, for sawdust, and from 90.78 to 99.64 and 86.44 to 99.46 percent, respectively, for bentonite clay. Analysis and calculation of separation factor (RL) of the result showed that adsorption of dye by sawdust and bentonite corresponds with Langmuir isotherm.

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There are different methods for treatment of composting leachate. Parameters dictating which method to be chosen include quantity and quality of the leachate, required amount of treatment and economical issues. Integration of ozonation and GAC adsorption into a single process is one of the attractive methods for post treatment of wastewater. Therefore, post treatment of composting leachate by means of ozonation and granular activated carbon (GAC) adsorption was considered as the main objective of this study. This study was conducted in laboratory scale and in batch mode. The set-up of batch system consisted of a Plexiglas column with 20 mm inner diameter and 800 mm height. The tall height of the column provides the required contact time between ozone and pollutants. Ozone was supplied to the column through a diffuser sited at its bottom. The outlet gas of the reactor may contain some residual ozone and can cause air pollution. Therefore, it is dangerous for the people working nearby the reactor. Thus, the ozone in the gas phase leaving the column was removed by KI solution. All experiments were conducted at room temperature (24 ±2°C). The leachate used in this study was obtained from the effluent of the Leachate Treatment Plant of Rasht Composting Facility (Guilan, Iran). All the chemicals employed for analysis were analytical grade and obtained from the reliable companies. In order to conduct the experiments, after complete determination of the specifications of GAC as an adsorbent, different dosages of GAC were added to 800 mL of leachate with the given initial concentration and pH in the column. The pH value of the solution was adjusted by Sulfuric Acid or Sodium Hydroxide as needed. Then the ozone gas was introduced into the column and the samples were taken in different intervals of time. After that required parameters of the samples were measured. Ozone generator (ARDA-COG 5S) with 5 gr/hr nominal capacity was used to produce ozone gas from pure and dry oxygen. Before starting each step of the experiment, the ozone generator was calibrated for ozone concentration. Pressure and flow rate of ozone gas produced was equal to 2 bara and 1 liter per minute, respectively. The results showed that integrated treatment of the leachate with ozonation and activated carbon adsorption, namely catalytic ozonation, was more effective than each process solely. In this study, COD removal rate of 44% in adsorption process, 57% in ozonation process and 80% in integrated process was achieved after 60 minutes. According to the results, in the integrated process, addition of the adsorbent (as long as it floats in the leachate) has positiveeffect on the removal of organic load. The pH value is another important parameter that affects the removal rate in the integrated process. It was found that removal of organic load is more evident at basic condition than at acidic condition. In this study, the maximum COD removal was achieved in the pH values between 8 and 9. Furthermore, in this process, ozonation along with adsorption process resulted in reactivation of activated carbon and avoided frequent GAC regeneration. After 5 times of the reuse of virgin GAC through a consecutive experiment, only 7% loss in COD removal was observed in the integrated process, while it reached to 95% for single adsorption process at the same condition. This can be explained either by the predominance of catalytic reactions rather than adsorptionoxidation reaction in the process or to the in situ regeneration of GAC.

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  Abstract: Hydroquinone is one of the most important phenolic compounds, which has a wide application in industries such as rubber, photo developing, cosmetic, and anti-oxidants. Because of its toxic effects, an efficient system should be provided for treating these kinds of wastewater. Therefore in this study, the performance of conventional and packed-cage RBC biological systems in treatment of wastewater containing hydroquinone, and parameters affecting the process were studied. In this study, the removal efficiency of hydroquinone was investigated in two different laboratory scale RBC systems. The first system was a two-stage RBC with rotating discs and the second one was a one-stage packed-cage RBC with bee-cell 2000 biofilm carriers. Each stage of the rotating discs RBC was consisted of 27 parallel plexiglas rotating disks with 15 cm in diameters. The packed-cage RBC had a net drum full of biofilm carriers with specific surface area about 650 m²/m³. Both systems had a total area of 2 m² and were fed by a peristaltic pump. During the startup, the reactors with sludge seed, daily dosage of 200 mg/L COD as glucose and synthetic wastewater was fed to each reactor. After increasing biofilm mass, the acclimation was started with stepwise substitution of glucose with hydroquinone (CODhdroquinone/CODtotal was increased about 10% in each step). After acclimation stage, the amount of COD was being increased stepwise up to 5000 mg/L. Both RBC systems as advanced biological processes had proper COD removal efficiencies for treating hydoquinone synthetic wastewater. Up to the maximum 90, 93 and 88 percent removal efficiencies were obtained in RBCI, RBCII and packed-cage, respectively for COD concentration of 1000 mg/L, hydraulic loading rate of 1.5 L/m³.d and optimum rotation speed of 10 rpm. Also, During the experiments up to 4000 mg/L influent COD, RBC with rotating discs had higher removal efficiencies (about 5%-15%) but at higher loading rates, packed-cage RBC had better results. The effect of hydraulic loading, and the rotational speed of disks in the performance of the both systems were studied. The results proved that the amount of hydroquinone removal increased with raising the rotational speed of the disks up to 10 rpm, and increasing hydraulic loading had a negative effect on the COD removal efficiencies in both conventional and packed-cage RBCs. Also COD concentration increased up to 10000 mg/L in one step whille the hydraulic loading rate and rotational speed were 1.5 L/m².d and 5 rpm, respectively. The results showed that conventional RBC had a better performance for the organic shock. For ensuring of hydroquinone biodegradation in the RBC systems carbon-13 NMR spectroscopy was also studied.

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Abstract: Water pollution due to toxic heavy metals has been a main cause of concern for the environmental engineers. Heavy metals are individual metals that negatively affect people's health. In very small amounts, many of these metals are necessary to support life. However, in larger amounts, they become toxic. Lead is one the important heavy metals that is applied in different industries such as manufacture of batteries, metal products and ammunition. Its standard limits in drinking water are 0.05 mg/L, because it affects all organs and functions of the body to varying degrees. The frequency and severity of symptoms among exposed individuals depends upon the amount of exposure. Lead entering the respiratory and digestive systems is released to the blood and distributed throughout the body. It is stored and may be released into the blood, re-exposing organ systems long after the original exposure. This is why the wastewater includes lead should be treated before discharging to the environment. Different kinds of physical, chemical and biological methods are used to remove lead. The main techniques are including precipitation, ion exchange, adsorption, membrane processing and electrolyte methods. Adsorption with many advantages is a proper method that is applied to treat heavy metal removal. In recent years, use of low cost materials as adsorbent for metal ion removal has been highlighted. Since natural absorbents are inexpensive and may be achieved without any cost and they are usually in abundance in nature, absorption of solute ions by these materials are a proper method to eliminate heavy metals from polluted waters and industrial wastewaters. In this study, following continuous column method, sawdust and ash, as two absorbents were used for removing lead. The experiments were carried out with the initial pH of 5 and different densities (50 and 100 ppm). In order to optimize the process of adsorption, three combined absorbents were also used which made from the above two absorbents with the ratios of 1:3, 1:4 and 1:6. Batch experiments were carried out in order to determine the parameters of adsorption. The results of sorption with sawdust have shown that Langmuir adsorption isotherm were suitable. Based on the results of the column experiments study, lead removal efficiency was more than 98 percent when combined absorbents were used. In batch experiments, the percent efficiency was 76 and 98 percent with sawdust and ash, respectively.