Optimization of rice wine fermentation process based on the simultaneous saccharification and fermentation kinetic model

Chinese rice wine making is a typical simultaneous saccharification and fermentation （SSF） process. During the fermentation process, temperature is one of the key parameters which decide the quality of Chinese rice wine. To optimize the SSF process for Chinese rice wine brewing, the effects of temperature on the kinetic parameters of yeast growth and ethanol production at various temperatures were determined in batch cultures using a mathematical model. The kinetic parameters as a function of temperature were evaluated using the software Origin8.0. Combing these functions with the mathematical model, an appropriate form of the model equations for the SSF considering the effects of temperature were developed. The kinetic parameters were found to fit the experimental data satisfactorily with the developed temperature-dependent model. The temperature profile for maximizing the ethanol production for rice wine fermentation was determined by genetic algorithm. The optimum temperature profile began at a low temperature of 26℃ up to 30 h. The operating temperature increased rapidly to 31.9 ℃, and then decreased slowly to 18℃ at 65 h. Thereafter, the temperature was maintained at 18 ℃ until the end of fermentation. A maximum ethanol production of 89.3 g.L 1 was attained. Conceivably, our model would facilitate the improvement of Chinese rice wine production at the industrial scale.

Design and preliminary experimental research on a new biogas fermentation system by solar heat pipe heating

Biogas fermentation requires appropriate temperature,while the biogas fermentation can be affected by the low ambient temperature in winter.In order to overcome the negative effects of low temperature fermentation,a new type of solar heat pipe biogas fermentation heating system was designed and a preliminary experiment research on this system was conducted using cow manure as the raw material at 6%concentration and total fermentation volume of 175 L.The experimental results showed that when the system was in normal operation,the fermentation temperature rose every day by gradient.This gradient will gradually become smaller with the increase of fermentation liquid temperature,and the temperature can reach 38°C after stability.Using this solar heat pipe heating system,the fermentation liquid temperature can be increased by 5°C every sunny day.This solar heat pipe heating system plays a significant role in biogas fermentation.The results of economic analysis show that the system can realize the fermentation at constant temperatures of 25°C and 35°C respectively,and it can also save standard coal equivalent of 40 kg and 80 kg in winter and spring,respectively.