Investigation of physical disintegration of toilet paper in wastewater system

Toilet papers are disposed of into sewer systems where they blend with other waste materials such as waste food and grease, personal care products, detergents, and cosmetics. Most of these substances can be absorbed by toilet papers to hinder their transport and disintegration in sewer systems. Subsequently, sewer blockages occur to create risk for human health, maintenance and aesthetic problems, and financial cost. In this regard, limited information is available about the fate of toilet papers in sewers. Therefore, physical disintegration of toilet papers as well as their chemical and microbial interactions must be investigated systematically.In this study, physical disintegration of toilet papers is studied as the first step toward understanding their behavior in sewer systems. We collected various tissue products from different parts of the world and characterized them based on their physical properties such as sheet thickness, basis weight, and specific volume. A mathematical model was developed to simulate physical disintegration of toilet papers under various turbulence conditions. This model was tested with physical disintegration experiments with two different toilet papers that are representative of most products around the world. The additional experimental and modeling work was conducted to elucidate effect of turbulence on disintegration of toilet papers. Turbulence conditions in the experimental system were compared with actual systems to identify critical sections of sewer systems where disintegration will be limited.Our results show that all of the major trends during physical disintegration of toilet papers were captured by our experimental and modeling studies. Our results show that the rate of physical disintegration increases along with the level of turbulence in the experimental system. Comparison of turbulence levels in the experimental system to those in actual sewer systems indicate that drains and small size pipes are critical sections of sewer system in terms of physical disintegration.