Toward Wet Wipes That Turn into Toilet Paper Debris When Flushed Through Reversible Biopolyelectrolyte Self-Assembly

Abstract

Wet wipes are widely used in cleaning and personal hygiene applications. However, they frequently contain plastic components that cause microplastic pollution and, even when marketed as flushable, have, in the case of many tested products, been found to agglomerate and clog pipes and pumps in wastewater collection and treatment systems. To this end, we present a method to create wet wipes using toilet paper infused with biopolymer gels that disintegrate in excess water. By infusing toilet paper with alginate or κ-carrageenan solutions followed by gelation, we generate wet wipes with tensile strengths that are comparable to those reported for commercial flushable wipes (≳100 N/m wipe width) and can be tailored by varying biopolymer and salt concentrations and numbers of base toilet paper layers. Using this approach, both alcohol wipes (formed through the gelation of alginate solutions in ethanol) and aqueous wet wipes (formed by gelling κ-carrageenan solutions in room-temperature, aqueous KCl) can be produced. Upon simulated flushing (i.e., immersion of the wipes in excess water, which causes the ethanol or KCl to diffuse out), the gel networks break down within minutes, reducing the tensile strength to that of wet toilet paper, and toilet/drain line clearance and Publicly Available Specification 3 (PAS3) Slosh Box testing confirms their effective dispersion upon flushing. Analyses of how the dispersed wipes affect the performance of wastewater bioreactors indicate that the degradation products from these wipes, at concentrations expected in wastewater treatment, should not disrupt municipal wastewater treatment processes. Collectively, our findings suggest that these toilet paper and biopolymer-based wet wipes could prevent clogging in wastewater pipes and pumps and reduce the accumulation of harmful plastics in the environment.