Sodium Hydrosulfite detoxification treatment of sugar solutions from lignocellulosic biomass

Sodium hydrosulfite produced by Hydro Technologies Inc. has shown significant potential in the detoxification of sugar solutions produced by hydrolysis of starch, hemicelluloses and cellulose. Preliminary work showed that depending on the level of inhibitors present in the solutions, the reducing power of sodium hydrosulfite favored the fermentation of sugars into ethanol, increasing the ethanol production up to 700% when inhibitors are present in the solution. These results also validated the effectiveness of the compound on sugar solutions that did not contain inhibitors originally. In such case, sodium hydrosulfite acted directly on the inhibitors formed by the yeast metabolism during the fermentation. Thus, it can be advantageously used both in first and second generation ethanol processes. These results also showed a favorable impact of sodium hydrosulfite for the fermentation of solutions from the hydrolysis of hemicelluloses and cellulose containing higher concentrations of inhibitors. In such case, sodium hydrosulfite treatment was combined to other detoxification processes. These results revealed a synergistic effect between treatments hence allowing to reach significantly higher fermentation yields. In this context, the objectives of this project are, on the one hand, to confirm the results on a larger scale on bioreactors of 2.5 L and secondly to confirm the feasibility of the technology on pilot fermentors with a capacity of 600L. The transition between the different scales will be accompanied by an optimization aimed at determining the most appropriate operating conditions leading to significant ethanol production increases. An in-depth economic study will also confirm the interest of hydrosulphite in an industrial context, thus enabling it to be marketed in the short term for the treatment of sugar solutions resulting from the hydrolysis of corn starch (actual market) but also medium term for the fermentation of sugars from hydrolysis of hemicelluloses and cellulose (forseen market).