Pretreatment with Ammonia

Alkali treatment with ammonia belongs to the physicochemical methods developed for pretreatment of biomass rich in lignocellulose. The main effects of ammonia pretreatment are the removal of the lignin fraction, partial solvation of hemicellulose, and decrystallization of the cellulose fraction. The structural changes of lignocellulose result in enhanced enzymatic hydrolysis either to produce fermentable sugars for ethanol production or to achieve increased biogas yields in anaerobic digestion processes. Different ammonia pretreatment processes are described such as soaking in aqueous ammonia, low-liquid ammonia treatment, ammonia recycle percolation, and ammonia fiber explosion. The parameters and effects of ammonia pretreatment on several kinds of biomass are reviewed.