Process for isolation of hemicelluloses from biomass pulping process waters or spent liquors

Process for isolation of hemicelluloses from biomass pulping process waters or spent liquors with removal of suspended solids, comprising the steps of:

• (a) providing an incoming stream (A) containing hemicellulose and coarse suspended solids having a size greater than 10 microns, fine suspended solids having a size within a range of 5-10 microns and colloidal substances, the incoming stream (A) having a pH;
• (b) adjusting the pH of the incoming stream (A) to yield a pH-adjusted incoming stream (C) having a pH within a range of 8-11;
• (c) feeding the pH-adjusted incoming stream (C) to a filtration unit for removal of coarse suspended solids (I) to produce a clear fluid stream (G) having a pH;
• (d) adjusting the pH of the clear fluid stream (G) to a pH within the range of 8-11 to dissolve hemicelluloses to form a fraction (G′) having dissolved inorganic salts;
• (e) removing fine solid particles having a size within a range of 5-10 microns and colloidal substances from the fraction (G′) to form an alternate fraction (J);
• (f) enriching hemicelluloses in the alternate fraction (J) to form a concentrate (L);
• (g) adjusting the pH of the concentrate (L) to a pH within a range of 4.0-4.5 to form a stream (N) having inorganic salts;
• and
• (h) removing inorganic salts from the stream (N) to form a final product.