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Background and purpose: Çhemical dyes used in textile industries involve some potential risks including carcinogenic and mutagenic effects in human. Furthermore, penetration of different dyes into surface and groundwater is a source of color in water reservoirs. This study aims at investigating the removal efficiency of yellow 3 and disperse yellow 3 reactive dyes by combined ÇÂÇ-SBR system.
Materials and methods: This experimental study was conducted on a batch scale and two SBR reactors were used. Wastewater samples used in this study were synthetic (ÇÔD=1800). Âfter setting up the reactors, yellow 3 and disperse yellow 3 reactive dyes were injected to the system and its removal efficiency was investigated during different reaction times. Âfter determining the SBR system efficiency in dye and ÇÔD removal, GÂÇ-SBR system efficiency was examined.
Results: During 24 hours of reactions, the efficiency of SBR and GÂÇ-SBR systems in the removal of reactive yellow3 dye was 58% and 72%, while for disperse yellow 3 it was 85 and 91%, respectively. Âlso, during 14 hours of reaction, the efficiency of SBR and GÂÇ-SBR systems for ÇÔD removal was 98 and 98.5%, respectively.
Çonclusion: The efficiency of GÂÇ-SBR system in the removal of reactive yellow 3 and disperse yellow 3 dyes was higher than that of the SBR system. However, their difference was insignificant regarding the ÇÔD removal. Ôverall, increase in the reaction time led to increase in the efficiency of systems and in a specific time of the reaction, their removal efficiency became uniform.

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Background and purpose: Solid waste leachate including different physical, chemical and biological pollutants is one of the most contaminated wastewater types. The limitations of conventional biological method for leachate treatment are the high energy consumption, nutrient requirement, sludge production, and cost. In this research, the efficiency of anaerobic baffled reactor modified by anaerobic filter (ABR-AF) was studied in solid waste leachate treatment located in Sari. Materials and methods: In this study, two glass reactors (six cells) were used. Each cell in upward section was equipped with a sampling port (and also a gas exit) and the volume of each reactor was 5.7 L. The initial cell was used for suspended solid settling and the last cell acted as an anaerobic filter in ABR-AF. The blank reactor characteristics were the same as the initial one except that it was without sludge and filter media. The interior temperature of the cells was adjusted by four electrical elements. After reaching the equilibrium, the leachate with different organic loading entered the reactor. Then, different parameters (COD, BOD5, TSS, o-phosphate, nitrate, ammonia, pH, etc.) were measured in different places of the reactors. All analyses were performed according to the “Standard Methods for the Examination of Water and Wastewater”. To analyze the data, analysis of variance and regression tests were performed in SPSS version 16. Results: The system efficiency for COD removal varied in the range of 39-96%. The maximum efficiency for COD removal was related to three days detention time and 10.72(Kg COD/m3.d) organic loading, while the minimum efficiency for it before the filter was related to one day detention time and 1.96 (Kg COD/m3.d) organic loading. The average efficiency for BOD5 removal varied from 39 to 58% and it ranged from 4 to 16% for o-phosphate removal. Conclusion: The ABR-AF system alone is not able to provide the effluent discharge requirement to surface and groundwater, but it can meet the needs of effluent discharge requirement to agricultural waterways.

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Hollow fiber membrane contactors have been applied in various industries e.g. chemistry, petroleum, biotechnology and medicine. They are also widely used in artificial organs e.g. artificial lung, kidney and liver as well as some pharmaceutical procedures such as separation and purification of biological materials. Intrinsic properties of hollow fiber membranes, such as high packing density and high mass transfer rate have increased the use of these membranes. In tissue engineering, using such membranes is of great importance for membrane bioreactors and culturing of cells sensitive to stress and those which require high mass transfer rates. This article comprehensively investigates the use of the hollow fiber membrane contactors applied in advanced medical sciences and pharmaceutics. Their composition materials in addition to the important factors affecting their performance characteristics are also discussed.

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Background and purpose: Direct application of sewage sludge in agriculture is limited due to the presence of pathogens, improper fermentation of organic waste and heavy metals in the sludge. Co-composting of sewage sludge and other waste is a method for safe and healthy disposal to reuse sewage sludge. This study investigated the possibility of producing compost from sewage sludge and pistachio hull waste. Material and Methods: A cross-sectional study was conducted in the winter of 2014 at the Environmental Health Engineering Research Center affiliated to Kerman University of Medical Sciences. First, a cylindrical reactor was made which was 30liters in volume, 30cmdiameter in dimensions, 45cm depth, and wall thickness of 6 mm. Pistachio hull waste with sewage sludge was mixed in a ratio of 1 to 4 and C/N ratio of 25. Reactor started with aeration rate of 5 liters per minute. The reactor content was mixed every five days, and the resulting compost samples were measured for moisture content, pH, electrical conductivity, organic carbon, total nitrogen, phosphorus, potassium, cadmium, and lead. Results: After 30 days from the start of composting process, the carbon to nitrogen ratio decreased to 16.5. During the composting process, pH increased but the amounts of electrical conductivity, total nitrogen, organic carbon, phosphorus, potassium, lead, and cadmium decreased. The maximum temperature reached 63ºc. Conclusion: The properties of the produced compost including temperature, pH, electrical conductivity, moisture ratio, C/N,P, K, and heavy metals were in category 1 and 2 of the standard compost of Iran.

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Background and purpose: One of the solutions for sludge production is to reduce that via decreasing the yield coefficient by oxic-settling anoxic process with different oxidation reduction potential (ORP) in sequencing batch reactor (SBR) activated sludge.
Materials and methods: We used 2 SBR reactors (20 L volume) that were controlled online. At a steady state in reactors, some parameters such as COD, DO, SVI, ORO, dry solids and moisture of sludge were tested during 12 months. Finally, yield coefficient and reduction rate of biological excess sludge were studied.
Results: At 10-day sludge age, the best removal efficiency of COD (95%) was seen without any sludge bulking problems and the kinetic coefficient Y and K_d were 0.58  and 0.058, respectively. The anoxic and anaerobic phase of the sludge holding tank showed that sludge storage after 7 hours in the reactor with ORP=-238 decreased the yield coefficient from 0.58 in the control reactor to 0.25g of biomass in g of COD. Consequently, the excess sludge decreased by almost 60%. On the other hand, compared to the control reactor (92 ml/g), the SVI reduced to less than 40 ml/g.
Conclusion: Using holding tanks in aerobic conditions with ORP greater than 230mv could cause appropriate settling and lead to a high efficiency of COD removal from wastewater.
 
 

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Background and purpose: CO₂ is the main cause of greenhouse effect. Previous studies have shown that CO₂ in methane and coal flue gas can lead to microalgae growth. The aim of this research was to study the CO₂ biofixation by Spirulina and injecting kerosene flue gas.
Materials and methods: A photo bioreactor was fabricated in which kerosene flue gas and air were separately injected. The photo bioreactor was filled by growth medium without carbon source. Light source was four fluorescent lamps (10 Klux intensity) operated in continuous and intermittent modes. The concentration of CO₂ was chosen in the range of 580 to 6000 ppm that was measured by NDIR CO₂ detector. The initial concentration of algae was 20 mgL^-1. The algal biomass production was measured during the experiment.
Results: The maximum production of algae by air and kerosene flue gas containing 5500 ppm CO₂ using artificial intermittent light was 0.07 and 0.41 gL^-1 d^-1 and maximum concentrations of biomass were 0.25 and 1.63 gL^-1, respectively. CO₂ biofixation rates were between 2.27% and 4.03% at different runs. Biomass productivity with intermittent light was 15% less than continuous light and it reached 1.91 gL^-1 with 5500 ppm CO₂ using continuous light.
Conclusion: In this study, the ability of a photo bioreactor was confirmed in the removal of CO₂. Also, increase in CO₂ contributes to increase in biomass production.