Research Of "Ethanol-Methane Coupled Process"

The effect of inhibit factors in Dual Coupling of Ethanol and Methane Fermentation Technology on ethanol fermentation was studied in this article. We explored available alternatives to reuse the anaerobic efflux and laid foundation for the process goes smoothly.Under the research, we found that both sulfite ion and sulfidion inhibited the ethanol fermentation. The remnants of total sugar reached up to 2.25%, and the starch utilization rate dropped to 79.66% at the end of the fermentation when there were 30mM SO₃^2- in the fermentation mash. With the increase of sulfidion's concentration, the remnants of total sugar reached up to 2.60% from1.62%, and the starch utilization rate dropped to 79.30% from 88.20%. The negative impact of these two substances on ethanol fermentation was caused by sulphur dioxide and hydrogen sulfide which were generated in low pH during the fermentation. The former one lead to more glycerol was produced, and then the ethanol yield decreased, as well as the starch utilization rate. The latter brought about the viability of the yeast decreased; severe cases could lead to the yeast fracture and die. And then, the fermentation process would be delayed or stagnated, the output of glycerol increased, and the starch utilization rate declined. Thus, we have to wipe of those reducing substances during the process of reusing anaerobic efflux to avoid the harmful effect they may cause to the ethanol fermentation.The ethanol yield was fell 4.49% compared to the blank when the anaerobic efflux was used as water for ethanol fermentation directly. It is not good for the utilization of raw material. So the anaerobic efflux must be treated before reused, if not, the ethanol fermentation will be influenced. Among the present resources recovery methods, mild oxidation, process of taking off the ammonia and activated carbon adsorption had great improved the character of anaerobic efflux for ethanol fermentation, the final ethanol yield was improved 1% compared to the constant. All of these were effective resources recovery methods. In consideration of economy and operability, we took the mild oxidation as the treatment of anaerobic efflux. It's low energy consumption. The anaerobic efflux treated by this method met demands for ethanol fermentation. The final ethanol yield (14.50%) was equal to the blank's (14.47%).After optimized the treatment of mild oxidation, we found that the best condition for industry was: temperature 55℃,ventilate, relative vacuum between -0.04 to -0.05MPa, and last for 160min. If the ventilatory capacity was bigger, the handling time would be shorter.We used the anaerobic efflux treated as the condition for ethanol fermentation. The final ethanol yield was a bit better than the deionized water's when the solid-to-liquid ratio was 1:3. The whole fermentation process was normal, the glycerol yield wasn't increased, and the final remnant of total sugar was less than 1%.The increase of pH during mild oxidation process was caused by decomposing of HCO₃^- and hydrolyzing of CO32-. The temperature was higher, the pH was higher. The ratio of alkalinity to ammonium-N went up also made the pH increased. In this process, alkalinity and ammonium-N decreased at the same time and the same equivalent (HCO₃^-and NH₄⁺). The pH was higher, the rate of getting rid of ammonium-N and alkalinity was higher. The finishing point of the process should be the concentration of ammonium-N less than 100mg/L.The steady of alkalinity in the anaerobic efflux was hooked on to positive ions. Main of those positive ions are NH₄⁺ and metallic cations. The concentration of NH₄⁺ and sodion are higher, they are 32.14% and 30.43% respectively. After treated by hydrogen type of cation exchange resin, the alkalinity of anaerobic efflux was removed completely. The hydrogen type of cation exchange resin adsorption could be considered as a treatment for removing alkalinity in industrial sewage.