Sharif Digital Repository

Due to the importance of environmental protection and the need to use new energy and alternative to conventional fuels, renewable energy has received much attention. Due to this necessity, a discontinuous bioreactor producing methane gas from animal waste has been modeled and simulated in this research. Monod kinetics was used to express the relationship between the growth rate of microorganisms and substrate concentration. The fourth-order Rong Kuta numerical method solved the substrate consumption and production of microorganisms and methane gas. The effect of the initial concentration of microorganisms on methane production has also been investigated. The initial concentrations of... 

Anaerobic digestion (AD) is a green technology that has been applied for many years. One of the main problems in this process is controlling these bioreactors to maximize methane production. A supervisory control strategy has been proposed to improve the methane production rate in an anaerobic digestion process while minimizing the risk of process failure in the presence of several drastic feedstock changes. The inner loop consisted of a feedback control that manipulated the feed flow rate for achieving the desirable methane production rate. A rule based control strategy was used as supervisory control loop. This controller received the total volatile fatty acids concentration in the reactor... 

Photocatalytic reduction of CO2 is considered as a promising strategy for production of a wide range of renewable hydrocarbon fuels by solar energy. In this investigation, a series of Ni and Bi doped TiO2 catalysts with different Ni and Bi contents were synthesized by the conventional sol-gel method and tested for CO2 photoreduction under visible light irradiation. Synthesized nano-photo-catalysts were characterized by XRD, FESEM, TEM, DRS, PL, FTIR and BET analyses. BET results indicated that the doping of Ni or/and Bi in the TiO2 framework resulted in BET specific surface area increment with respect to pure TiO2. DRS analysis showed that Ni doped TiO2, Bi doped TiO2, and co-doped samples... 

In current study, a meta-analysis approach was used to identify and evaluate the impact of various factors on the performance of integrated systems of anaerobic digestion with microbial electrolysis cell. In this study, related articles on the topic were systematically identified and collected according to the considered criteria, and the effect size that refers to the value of the difference between variables mean (total chemical oxygen demand (TCOD) removal rate and CH4 yield) was estimated. According to the meta-analysis, fed-batch operation mode, the range of 20< temperature ≤30 °C, metal cathodes, the range of 500< anode surface area ≤5000 cm2, HRT (hydraulic retention time) >20 days,...