Alginate extraction method
In a prior art reactor set up dense aggregates of microorganisms are formed, typically in or embedded in an extra cellular matrix. Such may relate to granules, to sphere like entities having a higher viscosity than water, globules, a biofilm, etc. The dense aggregates comprise extracellular polymeric substances, or biopolymers, in particular linear polysaccharides, The present invention is in the field of extraction a biopolymer from a granular sludge, a fibrous biopolymer obtained by said process, in particular alginate or bacterial alginate, and a use of said biopolymer.
1. A process for biopolymer extraction for obtaining fibrous biopolymer comprising the steps of
(ii) providing an ionic biopolymer aqueous solution, wherein the biopolymer is present in an amount of 0.1-40 wt. %,
(iv) adding, to the solution, 35-60 vol. % of one or more non-solvents, chosen from the group of acetone (dimethylketone), mono- or dialkyl ketones and alkoxy alkanol, under mixing, and
(v) extracting the biopolymer from the solution,
wherein weight c.q. volume percentages are relative to a total mass c.q. volume of the final solution.
2. The process according to claim 1 , wherein the biopolymer is alginate or bacterial alginate (ALE), comprising the step of
(i) extracting a mono-valent alginate or bacterial alginate (ALE) solution from extracellular polymeric substances obtainable from granular sludge.
3. The process according to claim 2 , wherein the granular sludge is one or more of aerobic granular sludge and anammox granular sludge.
4. The process according to claim 2 , wherein the extracellular polymeric substances are in aqueous solution at a concentration in the range of 0.1-30% w/w.
5. The process according to claim 2 , wherein the extracellular polymeric substances comprise a major portion consisting of exopolysaccharides, and a minor portion consisting of lipids and/or other components more hydrophobic than the exopolysaccharides.
6. The process according to claim 2 wherein the extracellular polymeric substances comprise at least 50 w/w exopolysaccharides.
7. The process according to claim 2 , wherein the granular sludge has been substantially produced by bacteria belonging to the order Pseudomonadaceae, and/or Acetobacter bacteria (aerobic granular sludge); or, by bacteria belonging to the order Planctomycetales (anammox granular sludge), or, combinations thereof.
8. The process according to claim 1 , comprising the step of, directly before adding non-solvent,
(iii) dissolving bioploymer under addition of 1-5 wt. % of a mono-valent salt of at least one of carbonate, hydroxide, hypochlorite, peroxide, and ammonia.
9. The process according to claim 1 , wherein the amount of non-solvent is 40-55 vol. %.
10. The process according to claim 1 , wherein extraction is performed by filtering.
11. The process according to claim 1 , further comprising
(vi) a work up step for retrieving non-solvent.
12. The process according to claim 1 , further comprising
(vii) a step of redispersing biopolymer by wetting with 0.1-10 wt. % acetone before redispersing.
13. The process according to claim 1 , further comprising
(viii) a step of sedimentation.
14. The process according to claim 2 , wherein the alginate is ammonium-alginate, and/or wherein the non-solvent is selected from mono- or dialkyl ketones, and alkoxy alkanols, such as iso propoxy ethanol, and further comprising a step of
(ix) heating the alginate to a temperature above 340 K, during a period of at least one minute to irreversibly transfer the alginate into alginate-amide thermoset resin under separation of water.