Mandrel-wound flocculant-containing fiber filtration tubes

1. A fiber filtration tube suitable for use in erosion control, having a cross-section and a length, said fiber filtration tube comprising

an inner portion being a void left by removal of a mandrel, the inner portion located at or proximate the center of the cross-section of the fiber filtration tube;

an outer portion spirally wrapped around and directly abutting the inner portion continuously along an outer peripheral of the inner portion, the outer portion including, prior to wrapping, a mat of natural fibers; and a flocculant.

2. The fiber filtration tube of claim 1 , wherein the mat of natural fibers includes natural fibers and a consolidating binder.

3. The fiber filtration tube of claim 2 , wherein the consolidating binder includes thermoplastic fibers.

4. The fiber filtration tube of claim 2 , wherein the natural fibers include wood fibers.

5. The fiber filtration tube of claim 1 , wherein the flocculant includes a soluble polyacrylamide homopolymer or copolymer.

6. The fiber filtration tube of claim 1 , further comprising a sheath of polymer netting surrounding the outer portion.

7. The fiber filtration tube of claim 1 , wherein the mat of natural fibers further includes bicomponent thermoplastic fibers, as a consolidating binder.

8. The fiber filtration tube of claim 1 , further comprising

a structure for preventing the outer portion of the fiber filtration tube from unwinding.

9. The fiber filtration tube of claim 8 , wherein the planar mat includes natural fibers and thermoplastic fibers as a binder.

10. The fiber filtration tube of claim 8 , wherein the outer portion includes a mat of 80% by weight or more wood fibers, and thermoplastic fibers, the thermoplastic fibers being present in an amount of less than 20 weight percent.

11. The fiber filtration tube of claim 10 , wherein the thermoplastic fibers are bicomponent fibers.

12. The fiber filtration tube of claim 8 , wherein the structure includes a sheath of netting.

13. A fiber filtration tube, comprising a plurality of fiber filtration tubes of claim 8 , adhesively bonded end-to-end and encompassed in a sheath of netting.

14. A fiber filtration tube, comprising a plurality of fiber filtration tubes of claim 1 , adhesively bonded end-to-end and encompassed in a sheath of netting.

15. The fiber filtration tube of claim 1 , wherein the mat of natural fibers includes wood fibers having a mean length of from 2 mm to 25 mm.

16. The fiber filtration mat of claim 1 , wherein the mat of natural fibers includes wood fibers prepared thermo-mechanically.

17. A process for the preparation of a fiber filtration tube of claim 1 , comprising

a) providing a mandrel;

b) winding around the mandrel a plurality of layers of a mat including natural fibers to form a fiber filtration tube;

c) supplying a flocculant in or on the mat;

d) securing the fiber filtration tube from unwinding; and

e) leaving in the mandrel if the mandrel is formed of biodegradable material, or removing the mandrel to form a void such that the mat directly abuts the void continuously along an outer peripheral of the void;

f) inserting a fiber filtration tube into a forming tube;

g) preparing a subsequent fiber filtration tube;

h) applying an adhesive to at least one of the fiber filtration tube inserted within the forming tool or to the subsequent fiber filtration tube; and

i) inserting the subsequent fiber filtration tube into the forming tube such that the ends of the fiber filtration tube within the forming tube and the subsequent fiber filtration tube inserted into the forming tube become adhesively bonded end-to-end.

18. The process of claim 17 , wherein the mat-includes a blend of wood fibers and thermoplastic fibers.

19. The process of claim 17 , further comprising inserting the fiber filtration tube into a sheath of netting.