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۱Biodegradation of phenol by new strain of thermophilic bacteria
نویسنده(ها): ، ، ،
اطلاعات انتشار: اولین کنفرانس بین المللی تصفیه فاضلاب و بازیافت آب، فناوری ها و یافته های نو، سال
تعداد صفحات: ۸
In the field of hazardous wastewater treatment the attention is focused on aromatic hydrocarbons because of their widespread presence in wastewater from petroleum refineries and petrochemical industries. Phenols are among the most hazardous contaminants in refinery wastewater and they are the most difficult to remove. Many techniques have been used in the past few years for removal of phenols. Biological treatment has proved to be the most promising and economical method for this purpose. Recent researches have shown that native microorganisms are more effective than commercial type. In this study, batch experiments were carried out to evaluate the biodegradation of phenol by thermophilic bacteria using free and immobilized cells at different conditions. This strain was isolated from the soil close to Tehran oil refinery which was characterized as Nocardia otitidiscaviarum. The bacteria were activated and gradually acclimatized to high concentrations of phenol of up to 1000 mg\l. The experimental results indicated that the biodegradation ability of this isolated strain is highly affected by temperature, pH, initial phenol concentration and abundance of the biomass. The biodegradation rate by free cells is optimized at 50 ºC, pH of 7 and phenol concentration of 600 mg\l. The higher phenol concentrations inhibited the biomass and reduced the biodegradation rate. However, the isolated strain still has the ability of degrading phenol at the concentration of 1000 mg\L. Cells acclimated to phenol can be adsorbed on the external surface the Monolith as the support where they grow to form a network of large filaments. Exponentially–growing cells were adsorbed faster than their stationary–phase counterparts. Immobilization resulted in a remarkable enhancement of the respiratory activity of cells and a shorter lag phase preceding the active phenol degradation.<\div>

۲Bioregeneration of GAC particles loaded with volatile aromatic compound in anaerobic bioreactor
نویسنده(ها): ، ، ،
اطلاعات انتشار: اولین کنفرانس بین المللی تصفیه فاضلاب و بازیافت آب، فناوری ها و یافته های نو، سال
تعداد صفحات: ۹
In this approach, toluene remediation from contaminated water in two steps containing solute adsorption onto granular activated charcoal (GAC) and solids waste regeneration in anaerobic bioreactor was investigated. Data showed that solute adsorption by GAC in closed system is highly successful in removing of toluene compound till standard water levels. This approach investigated that GAC particle as hazardous wastes, after loading with toluene hydrocarbon, can be regenerated by Thauera aromatica K172 in closed anaerobic bioreactor with nitrate respiration. Data highlighted the fact that 90% of contaminant onto GAC (100 mg toluene\ g GAC) can be biodegraded in batch unit, after 2 days. Also, the overall stoichiometry of toluene utilization onto GAC by biomass to nitrate reduction was 1: 6.2.<\div>

۳Modeling of nitrogen removal from ground water by MBBR
نویسنده(ها): ،
اطلاعات انتشار: اولین کنفرانس بین المللی تصفیه فاضلاب و بازیافت آب، فناوری ها و یافته های نو، سال
تعداد صفحات: ۸
The rise in Nitrate concentration in ground waters of many parts of the world including Tehran's aquifer is becoming very alarming. The source of Nitrate, apart from natural chemistry of soil is mainly contributed to leakage of sewage, industrial effluents and nitrogen based fertilizers. Due to this situation, denitrification of ground water is now gaining ground as public demand for high quality potable water is becoming an important issue. Nitrification and denitrification in Moving Bed Biofilm Reactors (MBBR) have emerged as a new technology for biological removal of harmful nitrogen compounds as nitrates and nitrites. The main advantage of MBBR reactors is due to their capacity for high removal rates and low operational problems such as clogging and settling. In this study biological denitrification method by moving bed biofilm reactor is investigated. Two packed type reactors in series with 3 liter volume each were designed in experimental set up and used in this research. Nitrification reactor worked under aerobic conditions and denitrification reactor was operated under anaerobic conditions. Methanol was used as carbon source in the reactors throughout the study. Liquid residence time was 8 hr in these reactors and 50% of reactor volume was occupied with KMT packing. The concentration of ammonium in these experiments were between 50–400 mg NH4–N\L at feed and the removal efficiencies of NO3–N was about 70% at steady state conditions. Having studied the rate of conversions under different conditions, behavior of nitrate and conversion of the ammonium to nitrate (nitrification) and nitrate to N2 was modeled in these reactors. It was concluded that, first the ammonium present in feed diffuses to the biofilm layer on the packings and by diffusing into autotrophic microorganisms layers consisting of nitrosomonas and nitrobacter, ammonia is used to produce nitrate. At second stage heterotrophic denitrifier bacteria convert nitrate to nitrogen. The behavior of ammonium take–up and nitrogen production was explained by a mathematical model. The model defined under the findings of this research can be used as a powerful tool for designing MBBR reactors for nitrogen removal from ground waters.<\div>

۴Modeling the treatment of industrial wastewater using anaerobic baffled bioreactors with artificial neural network
نویسنده(ها): ، ، ،
اطلاعات انتشار: اولین کنفرانس بین المللی تصفیه فاضلاب و بازیافت آب، فناوری ها و یافته های نو، سال
تعداد صفحات: ۷
In this study, the Artificial Neural Network model was used to model the behavior of anaerobic baffled reactors. In this model influent COD, hydraulic retention time and time to reach steady state condition were considered as input, while the output were the effluent COD and the concentration of volatile fatty acids (VFA). One hidden layer with 6 nodes related the input to the output data. Thus the structure of the proposed model is 3–6–2. The transform functions tried for the input neurons were the Sigmoid and Tangent functions and a Tangent function was used for the output. The Batch Back Propagation method (BBP) was used to train and test the neural network. Out of about 200 experimental data points used in this study, 80% were used for training and 20% for testing. The tests showed that the sigmoid function for the input data and the Tangent function for the output data performed well and are suitable. The network’s Average Relative Deviation (ARD) error for the predicted effluent COD and VFA was 2.97% and 6.09% respectively, demonstrating good accuracy and suggesting that the use of Neural Network modeling for the treatment of industrial wastewater using anaerobic bioreactors has great promise.<\div>
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