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Assessing the Impacts of Pulp Loading from Non-Dispersible Materials on Downstream Sewer Systems (WERF Report INFR1R14)
Citation:
Pastore, J. Assessing the Impacts of Pulp Loading from Non-Dispersible Materials on Downstream Sewer Systems (WERF Report INFR1R14). Water Environment Research Foundation, Alexandria, VA, 2015.
Impact/Purpose:
Benefits: •Results from grinding of five different brands of wipes used in this study show that the resulting shredded pulp, while demonstrating the potential to form rope-like shapes when removed from a screen during bench-scale testing, did not demonstrate the propensity to recombine during transit within various lengths of sewer lines, based on the results of live sewer testing. •Based on the observations stated above, in combination with the recovery of significant quantities of the shredded pulp during bench-scale testing, it is concluded that reduction in size of the whole (intact) wipes by a mechanical grinder leads to the decreased likelihood of sewer blockages and/or increased operation and maintenance costs associated with transport of these materials within the sewer. •Demonstrates that the shredded pulp from the wipes tested did not readily re-combine into rope-like forms capable of causing blockages during sewer transit.
Description:
Abstract:This study subjected wipes from five different manufacturers to a variety of tests to determine if changes to their physical characteristics occur when introduced into a sewer systemand what effect the shredded material (pulp) has on the downstream sewer. Shredded and nonshredded, wipes were used in the study utilizing specialized bench-scale testing and live sewer testing.Results from the benchmark testing and live sewer testing, within both local and regional sewer systems, indicate that the wipes used in the study were significantly reduced in sizethrough shredding and the resulting pulp, while increasing in weight due to water absorption, does not appear to cause clogging in the downstream sewer lines or exhibit noticeable odors. The pulp recovered during live sewer testing was found to consist of individual pieces less than two square inches in size. A small amount of pulp was observed binding with other background material in the sewer when grease and hair were present. The results suggest that shredding of the wipes by a mechanical grinder can minimize impacts to the downstream sewer lines by reducing the size of the material. Recommended actions include: educating the public on what to flush down the toilet, implementing an effective fats, oils, and grease (FOG) program and employing mechanical grinders ahead of pumps, when clogging due to non-dispersible material becomes a problem. [NOTE: The link below connects to a WERF site where the Final Report can be downloaded for free, after registering at the WERF site. For some projects the Executive Summary is available and can be downloaded for free without registering on the WERF site.]
