Process Development for the Detoxification of Fermentation Inhibitors from Acid Pretreated Microalgae Hydrolysate

Abstract

The aim of this study was to remove 5-hydroxymethyl furfural (5-HMF) and furfural, known as fermentation inhibitors, in acid pretreated hydrolysates (APH) obtained from Scenedesmus obliquus using activated carbon. Microwave-assisted pretreatment was used to produce APH containing glucose, xylose, and fermentation inhibitors (5-HMF, furfural). The response surface methodology was applied to optimize key detoxification variables such as temperature (16.5–58.5 °C), time (0.5–5.5 h), and solid–liquid (S-L) ratio of activated carbon (0.6–7.4 w/v%). Three variables showed significant effects on the removal of fermentation inhibitors. The optimum detoxification conditions with the maximum removal of fermentation inhibitors and the minimum loss of sugars (glucose and xylose) were as follows: temperature of 36.6 °C, extraction time of 3.86 h, and S-L ratio of 3.3 w/v%. Under these conditions, removal of 5-HMF, furfural, and sugars were 71.6, 83.1, and 2.44%, respectively, which agreed closely with the predicted values. When the APH and detoxified APH were used for ethanol fermentation by S. cerevisiae, the ethanol produced was 38.5% and 84.5% of the theoretical yields, respectively, which confirmed that detoxification using activated carbon was effective in removing fermentation inhibitors and increasing fermentation yield without significant removal of fermentable sugars.

The Sea's best kept secret: the use of seaweed as a source of biohydrogen for clean and renewable energy

“…For example, 5-hydroxymethyl furfural (HMF) and furfural by-products can be removed using activated carbon, leading to an increase in ethanol yields. 60 Related to this, the production of levulinic acid (through decomposition of HMF) has been determined to also inhibit the production of biohydrogen in literature works. 61 It is worth noting that some by-products, like HMF, have potential uses themselves such as in organic synthesis as a starting material.…”

Highly Efficient Production of Cellulosic Ethanol from Poplar Using an Optimal C6/C5 Co-Fermentation Strain of Saccharomyces cerevisiae

“…Although resin detoxification is effective, it often leads to significant loss of fermentable sugars [63]. Conversely, activated carbon detoxification results in minor Activated carbon detoxification is reported as an effective method for removing fermentation inhibitors while minimally reducing fermentable sugars, making it a more practical option for industrial applications [61]. Resin detoxification also exhibits a favorable inhibitor removal effect, particularly targeting weak acids, furan aldehydes, and phenols, and boasts renewable characteristics [62].…”

Adsorbents for the purification and recovery of biocompounds: An updated review

“…Activated charcoal also effectively removed fermentation inhibitors, increasing yields without significantly removing fermentable sugars. 95 Arminda et al 96 optimized the production of activated carbon from olive tree pruning residue to improve bioethanol production from the hydrolysate of the same residue. The optimal adsorption conditions removed 55% of the total phenolic compounds, 64% of 5-hydroxymethylfurfural and 41% of furfural.…”

“…Activated charcoal also effectively removed fermentation inhibitors, increasing yields without significantly removing fermentable sugars 95 . Arminda et al 96 .…”