Studies on the Recovery of Useful Materials from Disposable Diaper Waste using Pilot Stock Preparation Units

Abstract

Disposable diaper waste is consisted of plastic, fiber, and SAP (Super Absorbent Polymer). They are valuable to be used as raw materials of other products including plastic blocks and pulp mold. Nevertheless, disposable diaper waste have been disposed by landfill and incineration without recycling. Due to strict environmental regulations it is necessary to develop fractionation technique to recycle the disposable diaper waste. In this study the fractionation technique using pilot-scale stock preparation units was investigated. Process for separation of plastic and fibers from disposable diaper waste was composed by the combination of pilot-scale pulper, drum screen, screen and cleaner. Recovery rate of plastics and fiber was checked according to the various operating conditions. In drum screen, recovery rate of plastic was high when the cut size of disposable diaper waste was . The highest recovery rate of fiber was achieved with 0.3 mm slot screen. It is important to control the neutral state of SAP for improvement of recovery rate of fiber since SAP can be swelled easily in water. Therefore SAP can be controlled efficiently by the addition of calcium chloride into the pulper. Consequently recovery rates of plastics and fibers were over 90 and 80% under the optimum pilot operating conditions.