Flushed away: Flux, fate, and environmental impact of cellulose-based wet wipes within river systems

Allison, Thomas William 2025. Flushed away: Flux, fate, and environmental impact of cellulose-based wet wipes within river systems. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

As plastic pollution in aquatic systems becomes a growing concern, “biodegradable” wet wipes made from cellulosic fibres have emerged as popular alternatives. Marketed as eco-friendly and flushable, these products are commonly disposed of in toilets, yet their fate in freshwater environments remains unclear. This thesis investigated the environmental behaviour, degradation, and pollution potential of biodegradable, cellulosic wet wipes using a life cycle-based approach that integrated critical analyses, emissions modelling, and field experiments. First, this thesis critically evaluated wipe composition and theoretical degradation following flushed toilet disposal. Many wipes, despite green marketing claims, include blends of biological and synthetic fibres, alongside chemical additives that can limit microbial degradation. Their physical fragmentation is common, but molecular degradation is often incomplete, suggesting that most flushed wipes persist in the aquatic environment. An emissions model was then developed to quantify macro- and microfibre discharges to UK rivers and to assess the risk they pose. Results showed that wastewater treatment plants, sewer overflows, and land-applied sludge are major pathways. While solids are largely removed, microfibres can escape treatment, representing an overlooked pollution source. Wipe degradation and its environmental drivers were subsequently assessed under both controlled mesocosm and real-world river conditions. Tensile strength loss served as a reliable proxy for degradation, with cotton strip bioassays used as ecological controls. A first brand, composed predominantly of natural cellulose, degraded faster than a second, containing mostly regenerated cellulose. However, both persisted for over five weeks. In rivers, microbial biomass, total dissolved solids, and exposure time were key drivers of degradation, while scanning electron microscopy revealed greater surface wear in natural cellulose fibres. Despite their biodegradable labels, many wipes do not degrade rapidly in freshwater systems. Finally, the findings were synthesised to propose key recommendations for meeting safe, real-world, environmental standards. These included improved product design and testing protocols, clearer labelling and public education, and better wastewater and waste disposal systems to reduce fibre pollution from “green” consumer products.

Item Type:	Thesis (PhD)
Status:	Unpublished
Schools:	Schools > Biosciences
Subjects:	Q Science > Q Science (General)
Date of First Compliant Deposit:	29 September 2025
Last Modified:	29 Sep 2025 14:32
URI:	https://orca.cardiff.ac.uk/id/eprint/181378

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