Alcohol recovery from fermentation broth with gas stripping: system experimental and optimisation
Riga Technical University, Faculty of Civil Engineering, Research Centre for Civil Engineering, Water Research Laboratory, Kipsalas 6A–263, LV–1048 Riga, Latvia
*Correspondence: martins.strods_4@rtu.lv
Abstract:
Effective liquid biofuel production from various lignocellulosic waste resources is dependant not only on pre–treatment and hydrolysis but also on effective removal of alcohols from the fermentation media. Distillation and rectification is not suitable in low alcohol content systems (butanol production with clostridia) or in cases when the fermentation is performed in a continuous mode. One of the technologies offering continuous, in situ removal of alcohol is gas stripping. Despite the recognition of this technology, it is still under evaluation and adjustment. Thus, the aim of this study was to evaluate if gas stripping technology at rapid flow conditions is efficient enough to recover ethanol from the fermentation media. The results showed that 60 l min-1 flow rate was optimal to recover more than 45% of the available ethanol in 8 hours of stripping with nitrogen gas. The technology was efficient if the ethanol content in the fermentation broth was 10 wt%. At lower concentrations the recovery showed to be inefficient. Application of CO2 as the stripping gas was not suitable for ethanol recovery and should be tested prior use. In conclusion, the application of rapid N2 flow rate for gas stripping of ethanol from fermentation media showed to be an efficient technology and could replace long time, low flow rate stripping.
Key words:
alcohol recovery, biofuel, gas stripping, lignocellulosic biomass