Study On The Fermentation Performance Of Reused Water In The Ethanol-biogas Coupling Process

In the production process of fuel ethanol in Tianguan Group, produced a lot of waste water and high overall cost. It had anaerobic process, aerobic process and advanced treatment. The mesophilic anaerobic effluent as ingredients water in the"Ethanol-methane dual-fermentation coupled"process. the production is methane,waste free of the process. Due to the mesophilic anaerobic effluent as ingredients water can degradation of most organic substances, nitrosable substance can promote fermentation. In view of these problems, the mesophilic biogas slurry water was used as mixing water in this paper, the alcohol fermentation test was carried out using triangular flask and 1 cubic pilot platform. Wherein the biogas water as fermentation mixing water, synchronized to contrast tap water ingredients, the influence factors of the fermentation process was found out, providing a reference for the implementation of non waste drainage in the process of fuel ethanol production. The main research contents are as the followings:(1) Under the same fermentation conditions, the averaged concentration of ethanol fermentation liquid of the mesophilic anaerobic effluent is 0.06% relatively lower than that of the tap water, on this basis, pure cassava, corn, and mixing ingredients were used respectively. It was operated 50 batches continuously in 1 cubic test platform. The results show that the overall fermentation is steady, no obvious inhibition was observed. And both the qualities of mesophilic anaerobic effluent and high temperature anaerobic effluent is stable.(2) The mesophilic anaerobic effluent as ingredients water, the pH values of feed solution were regulated using sulfuric acid to achieve the optimal pH of liquefying enzyme, introducing a large amount of sulfate ions in the distillery wastewater and the high concentration of sulfate was extremely unfavorable to methane fermentation. Adjusting mesophilic anaerobic effluent by acidic liquor distiller’s grains and refining tower residual liquid water, the use of sulfate can be reduced. In comparison with that of tap water,11 batches of mixed water fermentation tests show that the average alcohol content of mixing water is 0.09% higher, and alcohol fermentation is not inhibited.(3) We carried out high concentration of mixed water fermentation test, and optimized the process of the high content of total residue sugar after finishing high concentration of fermentation, adjusting the adding time of the diastatic enzyme in batches, and controlling the reducing sugar content in the fermented liquid. The alcohol content in fermentation increased by 0.45%, and the total residual sugar decreased by 0.53%.(4) Through the analysis of economic benefit, in the production of It ethanol, coupled fermentation process reduces the production cost by 21.87% compared with the traditional process. After the application of the production line of an annual output of 100 thousand tons of ethanol, the production cost of 5 million 186 thousand yuan can be reduced for the Tianguan group.