Investigation On Acetone-Butonal Clear Liquid Fermentation And Recycling Utilization Of Fermentation Waste Liquid

.In clear liquid fermentation, raw materials were processed synthetically in order to remove the residue beforehand,then the sugar solution was used to fermentate,or the nutrients was completely utilized and the fermentation liquid was clear. Currently,clear liquid fermentation has been applied industrial production of ethanol,but there are few reports on clear liquid fermentation of acetone-butanol. In this work,acetone-butanol clear liquid fermentation was investigated using Clostridium acetobutylicum (8008,8012 CICC).The content of this work and results are as following:1) Acetone-butanol clear liquid fermentation was studied preliminary.Firstly,the fermentation was carried out with the semisynthetic medium in which glucose as carbon source, The highest solvent yield was only 8.43g/L,and much residual sugar was not being used,the results were not satisfied.Then the solution of brown sugar and white sugar were used to fermentate,brown sugar got higher utilization,solvent production was 14.50 g/L,that is because brown sugar contains more nutrients,but it was much lower than with corn as raw materials.Finally, when culture medium consisted of corn soaking solution and glucose,the solvent yield was up to 20.31g/L,the fermentation was good.2) With the corn starch as a carbon source,fermentations were carried out. In the experiment,when the fermentation was carried out using 50mL volumetric flask,the solvent yield between vacuum and without vacuum was almost the same,therefore,the vacuum operation was eliminated to simplify the process of the fermentation. The results showed that, the fermentation was good with corn soaking solution adding corn starch. the solvent yield was up to 21.63g/L, the appropriate corn soaking concentration was 200g/L,substrate concentration was 7%,α-amylase adding amount was 0.1%,fermentation period was 72h,cooking time was 45min.3) After clear liquid fermentation,recycling of waste liquid was studied.The fermentation waste and corn soaking solution was mixtured at different volume ratio. The results showed that,with the content of the fermentation waste liquid increased,solvent yield decreased.When the fermentation was carried out using waste liquid,solvent yield decreased from 21.63g/L to 0.96g/L,the role of restrain was prominent.Maintain the fermentation waste and corn soaking solution at the same volume ratio,adjusting the initial pH to 6.0,the solvent yield was still low,it need study further.4)The paper studied the effect of acid ion on acetone-butanol clear liquid fermentation which with corn starch as carbon source.The results showed that: SO32- has the strongest inhibitory action,and it enhance with the ion concentration increased.The fermentation is normal when the concentration that corresponding sodium salt,ammonium salt of SO42-,Cl-,CO32-,Ac-,PO43-is in the range of 0.2g/L～1.0g/L,the highest yield is achieved to 22.091g/L,When the concentration that corresponding salt of SO42-,Cl- increase to 2.0g/L,the solvent yield is decline slightly.Several kinds salt were mixed and added to the medium at different concentrations,the fermentation which there is not sulfite was normal,on the contrary,it was aberrant,the solvent production was low,the minimum was only 1.806g/L,Similarly showed that SO32- has strong inhibitory action on the fermentation.