Reduced dispersibility of flushable wet wipes after wet storage

Abstract

Scientific publications and newsfeeds recently focused on flushable wet wipes and their role in sewage system blockages. It is stated that although products are marked as flushable, they do not disintegrate after being disposed of via the toilet. In this work it is shown that wetlaid hydroentangled wet wipes lose their initially good dispersive properties during their storage in wet condition. As a consequence, we are suggesting to add tests after defined times of wet storage when assessing the flushability of wet wipes. Loss of dispersibility is found for both, wet wipes from industrial production and wipes produced on pilot facilities. We found it quite surprising that the wet wipes’ dispersibility is deteriorating after storage in exactly the same liquid they are dispersed in, i.e. water. This is probably why the effect of wet storage has not been investigated earlier. It is demonstrated that the deteriorating dispersibility of these wipes is linked to the used type of short cellulosic fibres — only wipes containing unbleached softwood pulp as short fibre component were preserving good dispersibility during wet storage. Possible mechanisms that might be responsible are discussed, e.g. long term fiber swelling causing a tightening of the fiber network, or surface interdiffusion.

Sewage Transport Volumes and Physical Degradation Rates of Personal Care Wipes

“…Recent studies on wet wipe dispersibility (Harter et al. 2021), and the presence of nonflushable and flushable wipes in marine sediments highlight the importance of additional research needed on this issue (Briain et al. 2020).…”

Technical Report: Hurricane Ida

“…In the sewerage systems of big cities like New York and London, the rise in wet wipes being used as toilet tissue and flushed into the sewer system by residents has led to a phenomenon known as "fatbergs," whereby this waste combines with other garbage and fats to create large masses clogging up sewer systems (Alda-Vidal and others, 2020). Although marketed as "flushable wet wipes," they do not disintegrate well after disposal, and in the U.S. up to $1 billion a year is spent dealing with the problem (Harter and others, 2021;Bowden, 2019). Awareness campaigns like "Trash It.…”

Deteriorating dispersibility of flushable wet wipes during storage: Role of fibre swelling and ionic shielding

“…Dispersibility ageing has been introduced in a recent publication, 23 where it was demonstrated that pilot-scale produced hydroentangled, wetlaid wet wipes can deteriorate their dispersibility over time, when stored in wet condition. The MMCF/synthetic fibres in a wet wipe were found to have no impact on this effect, which is supported by the results in Figure 5.…”

“…Wet wipes were made from the produced nonwovens using deionized water to simulate the usually applied lotion. In a recent work, it was demonstrated that dispersibility ageing is similar in wipes treated with water and usual lotion, 23 which was applied to the 125 × 175 mm cut sheets in a gravimetric ratio of 1:3. The wet wipes were stored in sets of three in sealed plastic bags.…”

“…In a recent work it was demonstrated that pilot-scale produced wet wipes deteriorate in their dispersibility during wet storage and the effect was named dispersibility ageing. 23 With this effect, it is possible to explain why never-wetted, dry nonwovens disperse well 5,6,10 and wet stored wet wipes do not. 11,12 The underlying mechanisms of dispersibility ageing are still not understood.…”