Iranian Journal of

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Background and Objectives: Measurement of light intensity is a recommended practice for insuring the delivery of required germicidal dose in disinfection operations by UV lamps. Use of sensitive to light chemicals which is the base of actionometeric methods could be considered as a suitable manner for estimating the intensity of UV lamp in circumstances that special radiometers are not available.
Materials and Methods: lodide-iodate mixture was used as an actinometer for this study. The light intensities of a UV lamp (LP 25W) were first determined by a special UVC ‌radiometer at certain distances from the lamp. Then the test of determining the suitable period of time for irradiation of actinometer was accomplished.  Finally، the color changes of iodide - iodate solutions at the predetermined distances were evaluated at the wavelength of 352 nm. The latter analysis can be done by a common (visible) spectrophotometer.
Results:‌ Results indicated that use of this actinometer is more suitable at the distances of 35 to 60 cm from the center of the lamp bulb، since iodode-iodate solution has a detectable color change at this range of distance in one minute irradiation which may be considered as a reasonable time for actionmeteric operations.
Conclusion:  Although all kinds of actinometers should not be regarded as precise as special radiometers and there would be need to use pure chemicals for actinometeric determination of light intensity، it can be claimed that the recommended procedure in this study which is the newest actinometeric method can be used in acceptable evaluation of UV intensity with least difficulty in providing necessary instruments.

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Background and Objectives: Phenolic compounds are presence in many industrial wastewaters, and have been classified as priority pollutants. Application of several conventional processes due to high cost and low efficiency has been limited. Thus, new methods such as enzymatic polymerization seem to be preferable and effective processes with high potential to substitute the conventional processes. This study was carried out to evaluate Raphanus sativus extract as a peroxides enzyme source for polymerization and removal of phenol from synthetic wastewater in the presence of hydrogen peroxide.
Materials and Methods: The study was performed in batch reactor at room temperature. Peroxidase enzyme was extracted from Raphanus sativus plant roots . Primary concentration of phenol in wastewater was 100 mgl-1. The concentration of phenol and enzymatic activity was been measuredby photometric assay.
Results: The results show that Raphanus sativus extract is a suitable source of peroxidase enzyme. Mean enzymatic activities in this extract was 3.107 Uml-1. Also, our results showed that elevation of extract volume lead to high efficiency of phenol removal, in which the increase in the extract volume from 5 to 50 ml, resulted in the efficiency of processes increased from 7.6 to 98.2 %. Also, sequencing addition of H2O2 and extract has improved the effects. The phenol removal efficiency of the reaction time after 3 h with single and three stages adding of reactants was 84.2 and 93.1% , respectively.
Conclusion:Enzymatic polymerization can be used as an appropriate process for the removal of phenolic compounds from wastewaters. To meet the optimized condition in process, the ratios of phenol/ enzyme and H2O2/ phenol and sequences of the adding of reactants should be considered.

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Backgrounds and Objectives:Safe drinking water providing is one of the main purposes in the community. Development and improvement of community is related to the public health. In this study !we studied the bacteriological quality of 116 villages under coverage of the water and wastewater companies in rural areas of Saqqez in.1386
Material and Methods:Drinking water of these rural areas have provided of deep, semi-depth- wells and spring water sources. Because in numerous rural areas both sources of drinking water and in some of them different sources of drinking water were used (old and new storage water source), in general, 359 samples were collected and transferred to the laboratory for testing to evaluate its quality. We also used linear Regression statistical analysis for collected data.
Results:results show that residual chlorine in drinking water in 33.88 percent of rural areas population were in range 0.2-1 mg/l. For 98.3 percent of the seqqez rural population, the turbidity was lower than the maximum permissible levels of drinking water standards of Iran (5 NTU). There was no any E.coli contamination in 88 percent of drinking water in saqqez rural areas.
Conclusion:Based on WHO guidelines concerning the microbial quality of water published in 2006! the average indicator for lack of E.coli in water of rural areas of seqqez was 88 percent and water is safe or good for drinking.

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Backgrounds and Objectives: Dyes  are  organic  materials  with  complex structures, toxic,  carcinogenic, teratogenic,nonbiodegredable properties and!the most!important pollutants of textile industrial wastewaters. The goal of this study was to survey the feasibility application of bone char (BC) as a sorbent for the  of methylene blue (MB) from synthetic wastewater.The sub goals of the research!were to determine!the adsorption isotherm, !effects of primary concentration of dye, adsorbent!dose, contact!time, and pH for the adsorption of MB with BC.
Materials and Methods: BC was prepared under laboratory conditions by using of electrical furnace at 400°C for 2h. The prepared BC was crushed and pulverized by standard ASTM sieves with range of 10-16mesh(1.18-2mm).The  chemical composition  and  solid  structure  of BC was  analyzed using X-ray diffraction(XRD) and  scanning  electronic  microscopy (SEM). Measurement  of  the surface area was carried out by N2 gas via BET isotherm and Belsorb software. The concentration of dye was measured by photometric!method (663nm).
Results: Predominant!compositionof BC is calcium hydroxyl apatite (Ca5 (PO4)3OH with 14m2/g surface area. The results of this study showed that increasing of primary concentration of dye, adsorbent dose and pH (5 to12) would lead to increasing of adsorption/removal of MB dye.Equilibration of dye adsorption was reached at lapse of 2h andoptimum pH for adsorption of MB with BC found in the rage of 8.5-12.Adsorption of MB witht BC complies witht freundlich isotherm(R2:0.99).
Conclusion: Bone char is a cheap component that can be used as an adsorbent in water and wastewater treatment. Based on optimum pH of 8.5-12 found for the removal of MB and the fact that many of textile!industrial wastewaters have an alkaline pH, this adsorbent can be!used for the removal of dyes from these wastewaters.

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BackgroundandObjectives: Dyes are organic compoundswith complex structures,which due to toxicity, carcinogenicity and nonbiodegredabity, this type of pollutants is one of the most important pollutants of the environment. The goal of this researchwas to study the feasibility of the application of solar irradiation in presence of potassium persulfate (K2S2O8) for the removal of Reactive blue19 (RB19) from synthetic wastewater.

 Materials and Methods:This research wascarri edoutin laboratory scalewith using of 200ml volume of batchphotoreactor.The effectsofoperatingparameters suchas concentrationofK2S2O8,pH,photoexposure time and preliminary concentrations of dye on decolorization have been evaluated.Different concentrations of pollutant inwastewaterwere prepared by solution of variousmasses of RB19 on tapwater. The reactors were exposedwith natural solar irradiation as aUVAsource from11 amto 14 pm.Themaximumabsorbtion wave length of this dye (!max) was determined by spectrophotometer (Unico, 2100). The measurement of dye concentrations was determined with using of standard curve and its best line equation

Results:Analysis of absorbtion spectra showed that the !max of RB19 is 592 nm. The average intensity of the UVA irradiated from solar system was 54.6 µW/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 photoexposure 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 K2S2O8 dosage leads to elevation of dye removal efficiency in 3h photoexposure time and K2S2O8 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.

Conclusion: 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.

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Backgrounds and Objective: Surfactants are one of the largest pollutants which exist in urban and industrial wastewaters. Large quantities of surfactants have entered to the environment since last decade due to increased use of synthetic detergent in industrial and home consumptions.In this study, the efficiency of UV/H2O2 process in removal of linear alkylbenzane sulfonate (LAS) from aqueous solutions was investigated.
Materials and Methods: In this study methylene blue active substane(MBAS)method and spectrometery were used to determine anion and residual surfactant respectively. In this study important variables were H2O2 concentration, initial concentration of surfactant, pH and duration of UV radiation. The effect of UV/H2O2 process on the degradation of LAS was analyzed statistically by using Multiple Linear Regression test.
Results: The resulted showed that after 20 minute, ultraviolet radiation solely removed 38.44 percent of Anionic detergent, Hydrogen peroxide showed no significant removal of detergent solution in the time course study. The efficiency of UV/H2O2 process in 10, 20 and 30 minute were to 86.2, 90 and 96.5 %, respectively.
Conclusion: The results showed that the efficiency of ultraviolet radiation and hydrogen peroxide process in anionic detergent was not significant thoogh it was considerable in combination process (UV/H2O2).

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Background and Objectives: Not paying attention to management and control of medical wastes in different stages of production, keeping, gathering, transporting and finally eliminating them all have been creating various setbacks such that the environment and human's health are in danger with the relevant consequences. This descriptive cross-sectional study was performed in Vali-e Asr, Amir Kabir, Taleghani, Amir Al-Momenin and Imam Khomeini hospitals of Arak city in 2009. In this research the current condition of gathering, maintaining, transportation and final elimination of hospital wastes of Arak city was investigated .Eventually an appropriate model was introduced.
Material and Methods: Solid wastes were separated, weighed and registered in two sequential intervals. In order to get acquaintance with the management procedure of medical solid wastes in the hospitals studied, a questionnaire approved byW.H.O was used. The questions were then replied by the Managers and Hygiene Experts worked at hospitals and their responses were recorded.
Results: The investigations conducted in 5 hospitals reveal that the average per annual was2.9 Kg in 24 hours per active bed and 4.6 Kg for each patient. This volume consists of 60% for semi-home solid wastes, 39% for infectious solid wastes, 0.34% for sharp wastes, 0.28% for the pathologic and 0.38% for medicinal and chemical solid wastes.
Conclusion: According to the results obtained in this study, in order to reduce pollution create in the hospitals, action should be taken to deal with pollutants at their source of generation. The staff members involved in waste collection and transportation should practice all the personal protection measures.finaly it also should be considered that,success in medical waste management wouldn't be achievable unless all groups of medical staff involved cooperate and participle.

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Background and Objectives: Heavy metal pollution has always been a major cause contamination of environment and considered as a major concern for food health. Rice is the most popular food among Iranians and presence of heavy metals in trace level in rice has received special attention because they are directly related to health.The aim of this research was to investigate the concentration of Pb, Cd, Cr, Ni in rice prevalent in the market of Iran.
Materials and Methods: 20 of the most widely consumed brands of Iranian rice were purchased from local market in Iran. 3 samples of each brand were collected and certain volumes of each sample were digested with acid. Heavy metal contents in the digested samples were determined by atomic absorption spectrometry.
Results :The results showed that mean concentration Pb , Cr , Ni in rice samples respectively was 0.387 , 0.683, 0.019 ( mg/kg )
Conclusion: Notably the Ni and Cr content in the rice samples was found to be below the food sanitary standards in India rice . In the other hand 50% samples content Pb was found to be upper the food sanitary (Pb: 0.3 mg/kg). The result indicated that weekly intake of heavy metal by rice was below the provisional tolerable weekly intake recommended by WHO/FAO. However, risk assessments needs considerable attention and better prevention this low pollution.

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Background and Objectives: Particular importance of hazardous wastes is due to having characteristics such as toxicity, flammability, corrosively and reactivity. Some of the chemical wastes due to having hazardous materials must be collected and managed in a proper manner, since they are potentially harmful to the environment. Owing to the fact that educational centers have important roles in developing countries, so the main objective of the present study was to investigate, hazardous waste management in chemistry laboratories of Ministry of Science universities, in Tehran, Iran.   
Materials and Methods: Study area of this research includes all chemistry laboratories in Tehran universities which were covered by Ministry of Science. To obtain the number of samples, based on Scientific Principles and identification formula, 64 samples were calculated. In addition, sampling was done by Stratified sampling. Validated checklists were used for data gathering. Data analysis were done by Descriptive statistics (mean, frequency and etc.) and inferential statistics (kruskal- wallis test).
Results: results obtained in this study indicate that Sharif University by obtaining the mean score of 60.5 and Tehran University by obtaining the mean score of 4.5-6 are placed in best and worst rank, respectively. Beheshty, Alzahra and Tarbiat Moallem univesities by acquiring the mean score of 20-28.5 have a same position in ranking table. 
Conclusion: Results show that most of the studied laboratories do not have any collection program and only 26.5 percent of them have acceptable programs.The separation and storing program observed in about 12.5 percent . Hazardous wastes' management in chemistry laboratory of Tehran Universities was not in good status. And from the standpoint of management, only 12.5 percent of studied cases are in good status, while 75 percent was in undesirable status.

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Background and Objectives: One of the complete treatment processes for industrial and municipal wastewater treatment is membrane bioreactor process which has dominant potential in process and operation sections. This study was conducted to compare the performance of extended aeration activated sludge (EAAS) with submerged membrane bioreactor (SMBR) systems in the treatment of strength wastewater, in the same condition.
Materials and Methods: The initial activated sludge was brought from the Plascokar Saipa wastewater plant. The Plexiglas reactor with effective volume of 758 L was separated by a baffle into the aeration and secondary sedimentation parts with effective volumes of 433 L and 325 L, respectively. The chemical oxygen demand (COD) concentration of the influent wastewater of the EAAS and SMBR systems were between 500-2700 and 500-5000 mg/L, respectively.
Results: Results showed that the SMBR system produced a much better quality effluent than EAAS system in terms of COD, biochemical oxygen demand (BOD5), total suspended solids (TSS) and ammonium. By increasing the COD concentration, the concentration of mixed liquor suspended solids (MLSS) and the removal efficiency of organic matter in the SMBR system, were increased regularly, however the removal efficiency of COD in the EAAS system was irregular. 
Conclusion: The average BOD5/COD ratio of effluent in the EAAS and SMBR systems were 0.708±0.18 and 0.537±0.106, respectively. These show that the organic matters in the effluent of the SMBR system was less degradable and thereupon more biological treatment was achieved. Nitrification process was completely done in the SMBR system while the EAAS system could not achieve to complete nitrification.

 

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Background and Objectives: Free living nematodes due to their active movement and resistance to chlorination don't remove in conventional water treatment processes thus can be entered to distribution systems and cause adverse health effects. UV irradiation can be used as a method of inactivating these organisms.
Materials and Methods: This study is done to investigate the effect of ultraviolet lamp on inactivation of free living nematode (Rhabitidae) in water. The effects of duration of irradiation, turbidity, temperature, UV dose and pH are investigated in this study. Ultraviolet lamp used in this study was a 11 watt lamp with intensity of 24 µw / cm².
Results: Contact time required to achieve 100% efficiency for larvae nematodes and adults were 9 and 10 minutes, respectively. Increase of turbidity up to 25 NTU decreased inactivation efficiency of larvae and adult nematodes from 100% to 66% and 100% to 64%, respectively. Change in pH ranged from 6 to 9 did not affect the efficiency of inactivation. With increasing temperature inactivation rate increased.
Conclusion: The results showed that there was a significant correlation between the increase in contact time, temperature rise and turbidity reduction with inactivation efficiency of lamp)p<0.001(. Also the effect of the lamp on inactivation of larvae nematode was more than the adults.

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MicrosoftInternetExplorer4 Background and Objectives: Nosocomial infection is the cause of deaths, morbidity, higher costs and increased length of stay in hospitals. Correct and appropriate use of antiseptic and disinfectants play an important role in reducing infections. In this study the efficacy of antiseptics on bacteria causing hospital infections has been studied.
Materials and Methods: This study was conducted in the laboratory of Imam Khomeini Hospital of Uremia. In this study the Antimicrobial activity of Descocid, Korsolex basic, Mikrobac forte and persidin 1% was studied against bacteria causing hospital infections such as Enterobacter aeruginosa 1221 (NCTC 10006), Staphylococcus epidermidis (PTCC: 1435 (Cip81.55) and Pseudomonas aeruginosa Strain PAO1. Sensitivities of bacteria were determined by Minimum inhibitory Concentration (MIC) and Minimum bactericidal Concentration (MBC) antiseptics. In the second stage, the concentration of antiseptics was prepared according to the manufacturer's suggested protocol and the effect of antimicrobial agents were studied at the certain concentration and contact time.
Result: All disinfectants (Descocid, Korsolex basic, Mikrobac forte) concentration and contact time, Accordance with the manufacturer's brochure, had inhibitory effect on all bacteria. That this is consistent with the manufacturer's brochure. Persidin one percent in concentration of from 2 and 4 V/V % and exposure time 5 minutes could not inhibit the growth of bacterial. But at concentrations of 10 and 20% respectively 15 and 30 minutes exposure time, all three types of bacteria can be inhibited, which is consistent with the manufacturer's claims.
Conclusion: In this study, the efficacy of antiseptics was determined with the Micro-dilution method recommended by the NCCLS. Korsolex basic, weakest antiseptics (the highest MIC) for the inhibition of three bacteria was determined. But Between all four antiseptics (according to manufacturer concentration), Only one percent Percidine 2 and 4 V/V %  in consumer dilution and 5 minutes exposure time failed to inhibit the growth of Pseudomonas aeruginosa, Staphylococcus epidermidis and Enterobacter aeruginosa.

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MicrosoftInternetExplorer4 Background and Objectives: Aniline has been used in different processes of chemical industries, however due to its side effects on the environment, several methods have been considered for its removal. In this study, we evaluated the performance of photocatalytic process using ZnO nanoparticles (nZnO) and ultraviolet (UV) irradiation for removal of Aniline from a synthetic effluent.
Materials and Methods: A 5L photocatalytic reactor made from Plexiglas, which the UV lamp (20w) installed in the center of that (inside a quartz jacket), was designed and nZnO (0.2-0.5 g/l) was being added into synthetic effluent with Aniline concentration of 250 ppm. After retention times of 30, 60, and 90 min, samples were centrifuged and supernatant was filtered using a 0.2 µ PTFE filter. The liquid-liquid method and Gas Chromatography instrument was used for extraction and analysis respectively.
Results: Results showed that the photocatalytic process of nZnO+UV could effectively remove Aniline from effluent. Increasing trend in the removal efficiency of Aniline using nZnO = 0.5 g/l was slower in comparison with other nZnO concentrations and the ANOVA analysis shows no significant difference between removal efficiency of Aniline in different concentrations of nZnO. The most removal efficiency of Aniline (76.3%) was observed in alkaline pH, retention time of 90 min and nZnO of 0.5 g/l.
Conclusion: It could be concluded that the photocatalytic process of nZnO+UV could be suitable technique for Aniline removal from effluents.

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Background and Objectives: The contamination of nitrate (NO3−) in groundwater resources causes two adverse health effects: induction of “blue-baby syndrome” (methemoglobinemia), especially in infants, and the potential formation of carcinogenic nitrosamines. The aim of this research is to investigate nitrate removal from groundwater using alumina nanoparticles and to determine the adsorption isotherms. Materials and Methods: This analytical-descriptive study was carried out at lab-scale, under batch conditions, and at room-temperature. The structure of alumina nanoparticles was determined using XRD, SEM, and TEM techniques. The concentration of nitrate in the solutions was determined by spectrophotometer at wavelengths of 220 and 275 nm. In addition, we investigated the impact of the important operational parameters including initial dose of Al2O3 (0.06-0.25 g/l), initial concentration of the solution (50- 300 mg/l), contact time (5-60 min), and pH (3-9). Moreover, we used Freundlich and Langmuir isotherm models to calculate equilibrium constant. Results: It was found that nitrate removal efficiency increased as we increased contact time, initial concentration and pH in batch system. A maximum of 60% nitrate removal was achieved under following conditions: 60 min contact time, pH 5, and initial nitrate concentration of 300 mg/l as N. The obtained results showed that the adsorption of nitrate by Nano-Gamma-Alumina follows Langmuir isotherm equation with a correlation coefficient equal to 0.982. Conclusion: Overall, our findings showed that the alumina nanoparticles can be used as an effective adsorbent to remove NO3 from aqueous solutions.

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Background and objectives: Bisphenol A (BPA) is an endocrine disrupting chemical that releases to the environment through effluents of its producing factory, pulp and paper mill factories, and plastics industry. The purpose of this study was to investigate adsorption isotherms of removing BPA from aqueous solutions using single walled carbon nanotubes (SWCNTs). Materials and methods: This study was an empirical investigation. Our experiments were conducted discontinuously using 50 mL of sample in each test. The variables of this study were the contact time (5, 15, 30, 60, 90, 120 min), the initial concentration of BPA (2, 5 , 20, 50 mg/L), and pH (3, 5, 6, 9, 11). The concentrations of BPA were measured using UV-Vis spectrophotometer. Results: The maximum adsorption capacity was found to be 71.42 mg/g. The results of our experiments showed that maximum adsorption capacity at equilibrium was achieved at t = 60 min and pH = 9. Moreover, increasing the initial concentration is associated with an increase in adsorption capacity until it becomes constant. Conclusion: The BPA adsorption on SWCNT follows Freundlich-Langmuir isotherm.

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Background and Objectives: Kidney patients in each dialysis cycle are exposed to extremely large volume of water, which is in direct contact with the patient’s blood. Hence, the occurrence of any type of contamination in the water used can be very toxic to patients. Thus, quality of water plays an important role in patient well-being. The aim of our study was to investigate the quality of water used for hemodialysis in Kashan Akhavan hospital.
Materials and Methods: This cross-sectional descriptive study was conducted on water quality used for hemodialysis in Kashan Akhavan hospital during Oct.-Nov., 2011. During the study a total of 26 water samples were taken from the raw water and inlet of hemodialysis instrument. Collected water samples were analysed for Heterotrophic plate count, residual chlorine, pH , K⁺, SO₄^2- , Na⁺, F- ,Ca²⁺ , mg²⁺ ,No^3- , Hg⁺ , Cd²⁺, Cr⁶⁺, Zn²⁺, Cu²⁺, Se²⁺ ,Co²⁺,Ag ⁺and As²⁺ according to the standard methods for water and wastewater examination.
Results: Our results showed that the concentration of copper, zinc, cadmium, lead, chromium, and silver were 0.4, 0.6, 0.07, 0.05, 0.08, and 0.04 µgL^-1 respectively. In addition, concentration of the chemical elements and heavy metals did not exceed the standard level in any cases. Moreover, no microbial contamination was observed in the samples analyzed.
Conclusion: Based on the results obtained, all water quality parameters in hemodialysis ward of Kashan Akhavan Hospital were compatible with AAMI (Association for the Advancement of Medical Instrumentation) water quality Standards and no health risk threatens the kidney patients.

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Background and objectives: Nowadays, landfilling is most common method in many countries owing to lower cost and adaptation to wide range of solid waste. Site selection of landfill requires evaluating several parameters such as municipal government requirements, environmental regulations and a large number of quantitative and qualitative criteria. The aim of current study was to compare AHP and TOPSIS in landfill site selection. For this purpose, two mentioned methods were applied to select suitable site in Karaj. Materials and methods: In present study, 4 candidate sites in south of Karaj were selected for landfill by overlaying data layers (digital maps) and query functions in Arc GIS 9.2. Prioritizations between alternatives were conducted by AHP and TOPSIS technique according to the criteria mentioned. Eventually, we compared and evaluated the AHP results and TOPSIS results with each other. Result: According to AHP, site prioritization was 3,2,4,1 respectively whereas, in the case of TOPSIS, it was ranked 4,3,2,1, respectively. These results showed that both methods are suitable to determine site priority. Conclusion: As in AHP, alternatives are compared with respect to goal and criteria, consequently it has better precision and higher accuracy and confidence compared with TOPSIS.

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Background and Objective: Various industries such as petrochemical, oil refinery, pharmaceutical, plastics, paper, steel and, resin produce a substantial of phenol and its derivatives. Wastewaters containing phenol need careful treatment before discharging into the environment due to their poor biodegradability and high toxicity. The objective of this study was to remove phenol by multiwall carbon nanotubes from aqueous solution. Materials and Methods: Adsorption process was implemented in a laboratory-scale batch with emphasis on the effect of various parameters such as contact time (5 to 120 minutes), pH (3- 11), initial concentration of phenol (5 - 50 mg/l) and the sulfate and chloride ions (20 - 200 mg/l) on adsorption process. To achieve a better realization of adsorption process, sorption kinetics and equilibrium isotherms were also determined. Results: The results indicated that maximum adsorption capacity occurred at concentration 50 mg/L and t =30 minutes. The uptake fluctuated very little in the pH range of 3–9, and at greater than 9 the absorption decreased suddenly. Moreover, the presence of sulfate and chloride ions had no effect on the process. It was found that adsorption kinetics and equilibrium data follow a pseudo-second-order kinetics model and a Freundlich isotherm model respectively. Conclusion: It is concluded that carbon nanotubes being effective in a wide range of pH, short time to reach equilibrium and the absence of competing ions on the absorption process can be used effectively in removing phenol from aqueous solution.

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Background and Objectives: In this experimental study, we used Analytical Hierarchy Process method to determine the best wastewater treatment process for dairy products factories. That is a multi-criteria decision making techniques and is based on expert knowledge. Materials and Methods: First, we formed the hierarchical structure and defined the main criteria and indicators. Then, we investigated the current situation of the treatment process through field observations and conducting influent-effluent analysis. Later, we converted the results obtained into quantitative indices. Then we weighted the main criteria, and their related sub criteria, depending on existing conditions we performed the experiments required and considered the experts ideas. Finally, Evaluation and prioritization of the options was conducted using Expert choice software. Then the sensitivity analysis was performed for main criteria and we evaluated the influence of the parameters weight change on the options. Results: In comparison with the main criteria, environmental criteria were more important followed by engineering criteria, economic and management criteria. Conclusions: Due to the influence of various parameters in choosing optimal wastewater treatment, Multi-criteria decision-making methods are necessary. Finally, “UASB + Aeration” was found to be the first priority followed by “Anaerobic filter + Aeration”, “Anaerobic lagoon + Aeration (2) + Sedimentation (2)”,” Anaerobic filter + Aeration (2) + Sedimentation (2)”. “Septic tank + Trickling filter + Aeration” system was found to be less preferable than other options.

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Background & Objectives: Excessive discharge of hazardous materials such as nitrogenous and organic compounds into the environment has negative impacts on the health of the aquatic environment. The main objective of this research was focused on evaluating the feasibility of using modified SBR reactor for the removal of nitrogenous compounds and chemical oxygen demand (COD). Materials & Methods: The experiments were performed using an up-flow continuous reactor with intermittent effluent. At first, four different cycles including aeration, settling, and decant (3, 4, 6, and 8 h) were designed for the performance of the reactor. Then, the efficiency of each cycle was determined for different concentrations of COD (250-1500 mg/L) and ammonia (40-100 mg/L). Results: Data demonstrated that all cycles had very good performances for the removal of COD. The average COD removal efficiencies of phases 1 through 4 were 91.7, 91.5, 92, and 92.7% respectively. The average NH^₄₊ removal efficiencies of phase 3 and 4 were 92.7 and 95.8% respectively. Conclusion: The performance of phase 4 (with the cycle of 8 h) for the removal of nitrogen compound and COD was particularly high. The combination of anoxic and aerobic cycles in the reactor and providing nitrate as an electron receptor had the best performance for the removal of nitrogen from wastewater. Therefore, the continuous up-flow reactor was a good alternative to batch reactor in removing nitrogen compound and COD simultaneously.