Physical characteristics, fiber types, and strength properties of wet wipes with respect to what is flushable

Wet wipes are relatively new products that are marketed worldwide as flushable, or non-flushable. Although flushable wipes have been disposed of into wastewater systems for some time, limited number of scientific studies have investigated their potential effects in wastewater operations. In this direction, this project quantified physical characteristics, fiber compositions, and tensile properties of wet wipes in relevance to their disintegration in wastewater systems. For this purpose, samples of flushable wipes as well as those of typical non-flushable wipes were collected from around the world. The samples were characterized based on their physical properties (e.g., basis weight, specific volume, thickness), tensile properties, and fiber compositions (fiber types). The experimental results indicated no clear difference between flushable, and non-flushable wipes on the basis of their physical properties, tensile properties, and fiber compositions. Comparison of wipes with toilet papers (TPs) indicated that wipes are larger (surface areas), heavier (masses), thicker, and denser (basis weight) than TPs. Fiber analysis showed that all wipes contain synthetic and relatively strong fibers such as rayon and polyester, while TPs are composed of only plant-based fibers. Inclusion of strong fibers into fiber webs of flushable wipes increase their strength properties such as the maximum amount of force needed to break a specimen (Fmax). Accordingly, Fmax value of flushable wipes averaged 7 N in their dry, and 5.9 N in their wet states, while the values were 3 N for dry TPs, and 0.29 for wet TPs. These numbers show an average reduction of 29% for flushables, and 90% for TPs as they go from dry, to wet states. Thus, nonwoven wipes have high initial wet strength, and they retain their strength in wet conditions much more than do TPs. Inclusion of strong fibers into nonwoven wipes is the key reason for why wipes cause blockages and clogs in sewer systems. The results serve as scientific support to develop technical specifications and standards for flushable products. The findings serve as feedback to manufacturers to improve existing products or to develop new ones, and to relevant stakeholders to develop standards & regulations to protect sewer networks, and public funds. Keywords: Wet wipes, flushable, characterization, wastewater systems