1. Pretreatment of used disposable nappies: Super absorbent polymer deswelling.
- Author
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Tsigkou, Konstantina, Tsafrakidou, Panagiota, Zafiri, Constantina, Soto Beobide, Amaia, and Kornaros, Michael
- Subjects
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POLYMERIC sorbents , *ANAEROBIC digestion , *PLASTIC recycling , *BIODEGRADABLE materials , *WATER masses - Abstract
• A pretreatment procedure for used disposable nappies was developed. • CaCl 2 and MgCl 2 were tested against their deswelling efficiency on SAP. • pH and solution volume did not affect SAP's deswelling. • Mixtures of CaCl 2 and MgCl 2 could reduce SAP's volume by 93% • Nappies hydrolysate can be used as substrate in co-digestion anaerobic processes. Typical used disposable nappies usually consist of nonwoven fabrics, Super Absorbent Polymer (SAP), and organic material, namely fluffy pulp, urine and/or excreta. Currently, this waste stream is being disposed to landfills causing many environmental issues. An alternative management method could be the valorisation of the biodegradable material through anaerobic digestion, and the recycling of plastics and SAP. Pretreatment of nappies is mandatory to separate SAP and plastics from the organic material. The aim of this work was the development of a process to minimize SAP's volume, as this component can swell up to 1500 times its own mass by water absorbance, thus hindering any further biological process. CaCl 2 , MgCl 2 , and a range of CaCl 2 /MgCl 2 combinations were tested against their deswelling efficiency on SAP, residual reagent concentration and reagent cost. The mixture of 20% CaCl 2 and 50% MgCl 2 (w/w) of SAP was concluded as the suitable combination of salts achieving a final SAP volume reduction of 92.7% with low residual cation concentrations and minimum cost. The physicochemical characterization of nappies' hydrolysate that took place to estimate its adequacy as substrate for anaerobic digestion resulted to a COD:N ratio within the acceptable range for a subsequent anaerobic digestion processing. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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