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Acetone–butanol–ethanol (ABE) is an intermediate product in the microbial fermentation process for producing biobutanol. ABE not only retains the advantages of oxygen-containing fuels but also redu...

Alcohols with three to five carbon numbers are renewable fuels for blending with diesel fuel, but the separation and purification of the alcohols from solution by fermentation is of great economic significance. If it is possible for alcohol and diesel blending system to contain part of water, the energy can be saved during the alcohol production process. Moreover, alcohols are more hygroscopic than diesel fuel, the blends of alcohols and diesel fuel will absorb water from ambient humidity if the tank is not adequately sealed during the storage and carriage and the excessive water concentration in the blends will cause phase separation. To avoid phase separation, it is important to test the blends of alcohols and diesel for their capacity to hold water. However, little study has been undertaken to systematically investigate the maximum allowable water concentration of alcohols and diesel blends. Therefore, in the current study, different three to five carbon numbers alcohols (n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, tert-pentanol) were prepared to blend with diesel to investigate the ability to hold water in the system at different ambient temperatures. The alcohol concentration of the blend varied from 10% to 90% in 10% increments in volume. Then water was gradually titrated into the blends by a high-precision pipette until it was no more a homogeneous liquid and the free water occurred, meaning t the start of phase separation. Results showed that all tested alcohols in this study could blend with diesel at any ratio without water addition. When ambient temperature was 0 and 30 °C, the allowable water concentration for butanol is the maximum in the system which is the first time to find out four carbon alcohols is the inflection point to be amphiphile in ternary fuel system. Among butanol isomers, tert-butanol could hold more water resulting of its special spherical structure compared to other isomers. Furthermore, to evaluate the influence of temperature on phase solubility, four different temperatures (0, 30, 50, 70 °C) were chosen. For alcohols (n-propanol, iso-propanol and tert-butanol) which were miscible with water, the allowable water concentration was gradually increased as increasing temperature. But for the other alcohols tested in this study, the water concentration admitted in the system gradually decreased with temperature increased.

To enhance eutrophic water improvement effect, three parallel lab-scale oxidation pond-vertical subsurface flow constructed wetland-stable pond combined systems with different microporous intermittent aeration positions were constructed. The purification effect of each system was determined, and the contribution rate of each part of the system was also calculated. The characters of bacterial community under different aeration positions were also analyzed. Microporous intermittent aeration rate of 5 mg/L was chosen as the aeration rate for follow-up experiment. The result showed that the best CODCr, total nitrogen, and total phosphorus removal efficiencies were achieved by the combined system with bottom microporous intermittent aeration, and the efficiencies were 71.04%, 79.52%, and 95.10%, respectively. The best ammonium nitrogen removal efficiency was 92.62% and was achieved by the combined system with surface microporous intermittent aeration. After analyses, 14 strains of bacteria associated with the removal of N elements were found and 8 strains of bacteria associated with P element cycle were found.

The microbial fuel cell (MFC) system is a promising environmental remediation technology due to its simple compact design, low cost, and renewable energy producing. MFCs can convert chemical energy from waste matters to electrical energy, which provides a sustainable and environmentally friendly solution for pollutant degradations. In this review, we attempt to gather research progress of MFC technology in pollutant removal and environmental remediation. The main configurations and pollutant removal mechanism by MFCs are introduced. The research progress of MFC systems in pollutant removal and environmental remediation, including wastewater treatment, soil remediation, natural water and groundwater remediation, sludge and solid waste treatment, and greenhouse gas emission control, as well as the application of MFCs in environmental monitoring have been reviewed. Subsequently, the application of MFCs in environmental monitoring and the combination of MFCs with other technologies are described. Finally, the current limitations and potential future research has been demonstrated in this review.