M. E. Kashfi; R. Kouhikamali; G. Khayati
Abstract
In this study, a mathematical model was used to predict the dynamic behaviour of the system under conditions of imperfect mixing in an Anaerobic Digestion (AD) process. To evaluate the system performance, the effect of mixing parameters by calculating the quantities of methane gas produced, system power, ...
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In this study, a mathematical model was used to predict the dynamic behaviour of the system under conditions of imperfect mixing in an Anaerobic Digestion (AD) process. To evaluate the system performance, the effect of mixing parameters by calculating the quantities of methane gas produced, system power, and effluent quality was investigated. Numerical results showed that with an increase in the mixing rate (α) by 20%, methane production rate, power production, and the effluent COD removal efficiency of the system increased by 19%, 19% and 12%, respectively. At an equal mixing rate, the amount of methane produced in influent with a concentration of 12.1% was 4.5 times higher than the influent with a concentration of 2.5%, while no significant change was observed in the effluent quality. Additionally, it was found that the mixing rate effect is more important than the mean cell retention time in the anaerobic reactor. The best fitted correlations for methane production rate and effluent COD removal efficiency using regression analogy at different organic loads of wastewater are presented.
M. Hezarjaribi; G. Bakeri; M. Sillanpaa; M. J. Chaichi; S. Akbari; A. Rahimpour
Abstract
The significance of toxic metals pollution treatment has become incrementally manifested as an important environmental issues in the recent years due to the urgent need to access healthy water and increase of the anthropogenic activities in water contamination. For efficient treatment of water contaminants, ...
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The significance of toxic metals pollution treatment has become incrementally manifested as an important environmental issues in the recent years due to the urgent need to access healthy water and increase of the anthropogenic activities in water contamination. For efficient treatment of water contaminants, the selective and novel materials are always welcomed. In this study, the hydrothermally synthesized titanate nanotubes (TNT) were modified by the mercaptosilane modifier for the removal of Cu(II) and Ni(II) toxic contaminants. The modified TNT adsorbent (TNT/Sil) was characterized in terms of the physicochemical aspects and then, the experiments for capturing metal cations were performed in batch mode. The modified adsorbent presented more affinity for the removal of Cu(II) than Ni(II).Theresults demonstrated thatthe experimental data were highly fitted to the Freundlich isotherm model and the maximum uptake capacities for Cu(II) and Ni(II) were found to be 53.77 and 45.29 mg g-1, respectively. In addition, endothermic nature of the adsorption process was predicted by the thermodynamic study as well as the pseudo-second order model that was corresponded to the kinetic data. Considering these achievements and due to the surface hydroxyl and thiol functional groups, TNT/Sil adsorbent could be effective and promising material in the purification of wastewaters, contaminated with toxic metal cations.
S. Saghafi; N. Mehrdadi; G. Nabi Bid Hendy
Abstract
Currently, the efficiency improvement of industrial wastewater treatment plant (IWWTP) has turned into a noticeable challenge for plants operator. In addition, decreasing the cost and energy consumption of wastewater treatment plants has attracted great interest by water agencies and IWWTP operators. ...
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Currently, the efficiency improvement of industrial wastewater treatment plant (IWWTP) has turned into a noticeable challenge for plants operator. In addition, decreasing the cost and energy consumption of wastewater treatment plants has attracted great interest by water agencies and IWWTP operators. Since IWWTPs are energy-intensive facilities, the need for cost-efficient and reliable treatment processes has significantly increased so as to meet the standards of environmental regulations and national goals. Determination of energy efficiency of IWWTPs is a starting point for any energy-saving initiative. In this paper, a case study has been carried out in 79 WWTPs in Iran's industrial zones to identify electrical energy efficiency indices (EEI). In order to achieve a reliable result, Data Envelopment Analysis (DEA) was applied by Lingo11 software. The electrical energy efficiency index was estimated by regression equations for plants with different level of treatment (ready to discharge to the river, irrigation of green spaces, and agriculture) using Minitab17 software. The obtained results enable IWWTP operators to identify the cost items to improve the productivity at plants.