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Microbial fuel cell, as a promising technology for simultaneous power production and waste treatment, has received a great deal of attention in recent years; however, generation of a relatively low power density is the main limitation towards its commercial application. This study contributes toward the optimization, in terms of maximization, of the power density of a microbial fuel cell by employing response surface methodology, coupled with central composite design. For this optimization study, the interactive effect of three independent parameters, namely (i) acetate concentration in the influent of anodic chamber; (ii) fuel feed flow rate in anodic chamber; and (iii) oxygen concentration in the influent of cathodic chamber, have been analyzed for a two-chamber microbial fuel cell, and the optimum conditions have been identified. The optimum value of power density was observed at an acetate concentration, a fuel feed flow rate, and an oxygen concentration value of 2.60 mol m−3, 0.0 m3, and 1.00 mol m−3, respectively. The results show the achievement of a power density of 3.425 W m−2, which is significant considering the available literature. Additionally, a statistical model has also been developed that correlates the three independent factors to the power density. For this model, R2, adjusted R2, and predicted R2 were 0.839, 0.807, and 0.703, respectively. The fact that there is only a 3.8% error in the actual and adjusted R2 demonstrates that the proposed model is statistically significant.

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Over the last few decades, steady growth in desalination literature has been observed. However, conducting a quantitative analysis of this literature is still a novelty. This study aimed at carrying out a quantitative analysis of desalination literature published during the last 30 years, using bibliometric and content analysis techniques, based on the Web of Science database. The bibliometric analysis revealed that desalination has received much attention after the year 2000, as 95.4% of literature has been published in two decades after 2000. The text mining analysis showed that the hot themes of desalination research are reverse osmosis optimization, graphene implications, interfacial polymerization, capacitive deionization, carbon nanotube implications, and antifouling techniques. Furthermore, it was observed that many desalination technologies have emerged recently that make it a challenge to choose the right desalination technology for industrialization. Therefore, this study also contributed to identifying the factors that are important for the industrialization of desalination technologies and, based on these identified factors, this study has compared different desalination technologies to unearth the energy-efficient and low production cost technology. Analytical hierarchy process was used for comparing existing desalination technologies based on eight different parameters and it demonstrated that reverse osmosis is the best available technology for desalination.

Energy production from clean and green sources is one of the eminent challenges to mankind. Overall, all industrial sectors contribute to CO2 emission, but the energy production sector is a major contributor. In recent years, CO2 emissions from the energy sector have increased by 1.7%. Therefore, the development of alternative energy production sources is a pivot for researchers. In this regard, the fuel cell has been a promising technology but still accompanied by the release of greenhouse gasses but relatively lower than that of fossil fuels. The integration of the fuel cell to the biogas has been a promising factor to reduce emissions. This study contributes to the same by producing a self-sustaining biogas-fuel cell multigeneration system for cold areas. Mathematical modeling of all complements of the system, i.e., anaerobic digester, solid oxide fuel cell, solar collector, and thermal storage system, is provided. MATLAB/Simulink environment is used for simulation of the system. The proposed system will use an anaerobic digester for methane production. Hence, produced methane will be used to power solid oxide fuel cell. The electricity of the fuel cell will power the residential place, and the thermal potential of the exhaust will be stored. In daylight, the solar thermal potential will be utilized for district heating. In the absence of solar light, stored thermal energy will be used for district heating and hot water supply. Additionally, the CO2 emitted from the system will not be released into the environment but stored for industrial purposes. The best area of application of the proposed system is cold areas such as Switzerland.