Method for producing recycled water-absorbent resin, and method for assessing production conditions in said production method

A method for determining production conditions in a method for producing a recycled water-absorbent resin from a water-absorbent resin contained in a used absorbent article,

• the water-absorbent resin containing a polymer having partially neutralized carboxyl groups,
• the method for producing a recycled water-absorbent resin including:
• a dehydration step (1) of treating the water-absorbent resin with a polyvalent metal salt;
• an acid treatment step (2) of treating, with an acidic substance, the water-absorbent resin treated with the polyvalent metal salt;
• a water washing step (3) of washing with water the water-absorbent resin treated with the acidic substance;
• a neutralization step (4) of neutralizing, with an alkali metal salt, the water-absorbent resin washed with water;
• and
• a drying step (5) of drying the water-absorbent resin neutralized with the alkali metal salt and thereby producing a recycled water-absorbent resin, and
• the method for determining production conditions in the method for producing a recycled water-absorbent resin comprising determining an end point of the acid treatment step (2) on the basis of a pH of a dispersion of the water-absorbent resin treated with the polyvalent metal salt and containing the acidic substance added during the acid treatment step (2).