Method for recovering pulp fiber from used sanitary product and recycled pulp obtained thereby

13:

• A method for recovering pulp fiber from a used sanitary product including pulp fiber and a polymer absorbent, comprising the step of:
• treating the used sanitary product with an ozone-containing gas to decompose and remove at least a portion of the polymer absorbent in the used sanitary product which decomposed and removed portion of the polymer absorbent is gasified and removed as carbon dioxide, wherein a product of the ozone concentration of the ozone-containing gas and the treatment time with the ozone-containing gas is 500 to 12,000 m−3·g·min.

14:

• The method according to claim 13, wherein the ozone concentration of the ozone-containing gas is 50 to 200 g/m3.

15:

• The method according to claim 13, wherein the treatment time with the ozone-containing gas is 10 to 60 minutes.

16:

• The method according to claim 13, wherein the used sanitary product is treated with the ozone-containing gas to decompose and remove at least 90% of the polymer absorbent in the used sanitary product.

17:

• The method according to claim 13, further comprising the steps of:
• stirring the used sanitary product that has been treated with the ozone-containing gas, in an aqueous solution or in water to decompose the used sanitary product into its constituent elements, and
• separating the pulp fiber from the decomposition product obtained by the decomposing step.

18:

• The method according to claim 13, comprising a step of separating apart at least a portion of the elements composing the used sanitary product and/or breaking up a portion of the used sanitary product before the step of treating the used sanitary product with an ozone-containing gas to decompose and remove at least a portion of the polymer absorbent in the used sanitary product.

19:

• The method according to claim 13, further comprising a step of drying the pulp fiber, the step of drying the pulp fiber resulting in dried pulp fiber having a moisture content of 5 to 13%.

20:

• The method according to claim 19, wherein the pulp fiber is dried at a temperature of 100 to 200° C.

21:

• The method according to claim 14, wherein the treatment time with the ozone-containing gas is 10 to 60 minutes.

22:

• The method according to claim 14, wherein the used sanitary product is treated with the ozone-containing gas to decompose and remove at least 90% of the polymer absorbent in the used sanitary product.

23:

• The method according to claim 15, wherein the used sanitary product is treated with the ozone-containing gas to decompose and remove at least 90% of the polymer absorbent in the used sanitary product.

24:

• The method according to claim 21, wherein the used sanitary product is treated with the ozone-containing gas to decompose and remove at least 90% of the polymer absorbent in the used sanitary product.

25:

• The method according to claim 13, wherein after decomposition a polymer absorbent mass of the decomposed used sanitary product is reduced by 43.8% to 100%.

26:

• The method according to claim 13, further comprising a step of discharging the carbon dioxide together with the ozone-containing gas.