Tom Allison

(he/him)

BSc MSc

Publication

• Date
• Type

Research

Thesis

Flushed Away: Flux, Fate, and Environmental Impact of Cellulose-Based Wet Wipes within River Systems

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 investigates the environmental behaviour, degradation, and pollution potential of biodegradable cellulosic wet wipes using a life cycle-based approach that integrates critical analyses, emissions modelling, and field experiments.

First, this thesis critically evaluates 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 is then developed to quantify macro- and microfibre discharges to UK rivers and to assess the risk they pose. Results show 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 are 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 are synthesised to propose key recommendations for meeting safe, real world, environmental standards. These include 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.

Funding sources

Engineering and Physical Sciences Research Council (EPSRC) Sustainable Plastics DTP

Supervisors

Isabelle Durance

Professor and Director of the Water Research Institute