By Kevin Bates
Wastewater professionals are well aware that debris has changed significantly over the last ten years. From the bus-sized “fatberg” festering within London England’s sewer system, the pending “wipes” lawsuit in Minnesota and public outreach efforts to change consumer behaviour, municipalities are frustrated by seemingly innocent flushables.
Not only is the waste running through our system tougher and more prevalent than ever before, our aging infrastructure simply can’t keep up. Undersized, original equipment is especially prone to clogging and breakdown. Gradual pipeline and channel deterioration compounds that problem exponentially.
However, manufacturers and wastewater professionals can equip themselves with the right tools to completely eliminate problems caused by non-dispersibles in pump stations and resource recovery facilities, even if legal and public education efforts do not curtail the problem.
The waste evolution
The prevalence of wipes in the waste stream is a relatively new problem. Introduced in the early 2000s, they were commercially marketed for household cleaning and “flushable” bathroom use. These products presented convenience, hygiene and performance benefits, along with an appealing price for consumers. While the early versions didn’t gain immediate, widespread popularity, the popularity of recent ones has skyrocketed.
Disposable wipes sales are rising at double-digit rates and are now a $5 – $6 billion product category. Those figures are only expected to increase. According to a 2013 report by the Association of the Nonwoven Fabrics Industry, wipes usage is expected to grow 16% year-over-year through 2017.
In the early days, these “flushable” products were merely resized versions of baby wipes. They were cloths made of a stretchy, ultra-durable plastic material known as spunlace, impossible to break apart with water alone. In recent years, most commercial wipes manufacturers switched to a cellulose substrate, which offers slightly better dispersibility without sacrificing strength. However, this material still causes clogging and requires intervention, in order to fully break down.
Wipes manufacturers contest that the fabrics causing the most damage at pump stations and treatment facilities are actually non-flushable wipes, like paper towels and feminine care products, and disposable wipes products labeled as flushable. However, facility operators are seeing things differently. According to a debris evaluation study by the Maine Wastewater Control Association, 90% of the products pulled from the waste stream during the testing period were not flushable. Almost half of that total included so-called flushable wipes.
Along with increased durability, this new generation of wipes comes with confusing terms attached. “Flushable” is often assumed to mean “biodegradable”, so there is a misleading assumption that the material will behave like toilet paper and eventually dissolve. It’s only when problems from repeated flushing of these kinds of wipes leads to costly and unseemly consequences, usually in the form of a toilet backup, that consumers begin to think about how that material behaves within a pipeline.
The damage caused by wipes and other non-dispersible material to pumps, pipes and sensitive treatment equipment, such as membrane bioreactors (MBRs), is overwhelming. From public outreach campaigns to smarter pump station and treatment facility design, industry professionals are beginning to combat this tough debris more thoroughly and successfully.