No more clogging of pumps
Ensuring wet wipes do not lead to excessive wastewater charges
To keep wastewater operational costs and downtime to a minimum, operators expect a high level of reliability from pumps - even during incidents of heavy rain. This is an important aspect in these times of increasingly marked climate fluctuations. High degrees of efficiency are also expected from pumps so that wastewater can be pumped through the wastewater pipes and sewers energy efficiently while conserving resources.
Plant operators are also facing entirely different challenges. Population habits have changed, with water consumption in households having dropped severely during the period from 1990 to 2004 by approx. 14 percent. Peoples' habits with waste are also changing. Waste and refuse are increasingly landing in the sewer system although they have no business being there. Items such as:
- Wet wipes or “flushable” wipes, cosmetic wipes and baby wipes
- Disposable cleaning cloths
- Cotton swabs
- Tampons and panty liners
- Clothing and textiles
- Plastic bags, plastic debris
Incorrect disposal methods via the wastewater pipe are causing problems
In particular the sale of wet wipes has increased rapidly by around 200 % over the past few years. Whereas in the past they were used almost exclusively for baby care and were disposed of as household waste together with diapers, wet wipes and cosmetic wipes are today part of day-to-day hygiene and are increasingly landing in sewage pipes. It is easy to see why wet wipes are causing such problems: More and more fibers are entering the sewer system but with less and less wastewater. This combination is leading to pumps clogging and increasing wastewater fees for consumers. Few people are aware that legal regulations prohibit the disposal of wet wipes or similar items via the toilet. Notes on wet wipe packaging informing consumers that they should be disposed of via household waste are often lacking or else written very small. In addition, they are often in places where consumers can overlook them easily. Other modern hygiene items like clothing and textiles are also increasingly being disposed of via sewage pipes.
The seven stages of flushability
Details on flushability can be found on many wet wipe packages. These are based on a voluntary test initiated by the European Association of Nonwoven Manufacturers Edana with respect to the flushability of wet wipes in toilets. These seven stages of flushability are however, in the opinion of experts, meaningless for wet wipe problems in sewers as the test finishes just after the toilet's wastewater pipe. Tests often pay insufficient attention to whether the highly fibrous cosmetic wipes disintegrate in the sewer system at all and to what degree say the experts. What is known is that the length of time wet wipes need to decompose depends very much on the type of nonwoven material. One thing is certain however: more and more undecomposed wet wipes are leading to clogging of pumps and are entering the screens of sewage treatment plants entirely without having undergone any disintegration. The length of time they remain in the sewer system is much too short for greater decomposition phenomena to occur. At the same time, low prices are leading to ever shorter usage times for clothing and textiles. Frequently, cleaning cloths, floor rags or underwear are no longer landing in waste but are likewise being disposed of via the wastewater pipe. This is creating additional fibrous loads in the sewer system.
Fibers as a cause of clogging of pumps, screens and wastewater pipes
Once they get into the sewer system, sanitary products like panty liners, and textiles like cloths and wet wipes become a problem for wastewater technology. Wet wipes are neither easy to separate nor can entangled wet wipes be prevented very easily. Instead, components regularly fail due to their presence, with entangled material causing clogging of pumps, valves and wastewater pipes. Even pumps developed by industry with freewheel -- a large spherical passage -- can only handle these entangled materials and the resultant clumping to a limited degree. Operating companies therefore have to combat a significant drop in efficiency with pumps equipped in this way.
Increased costs due to clogging nationwide
The reality is that, in many locations, weekly or even daily elimination of malfunctions has become part of everyday working routines. In a report by the German broadcaster WDR from 2017, annual costs of 40,000 euros were reported for cleaning just one pump in a sewage treatment plant, the main cause of which was identified as wet wipes. The Berlin Municipal Water Authority estimate the costs caused by problems with wet wipes to be up to 800,000 euros per year.
Wet wipes - how the right wastewater technology prevents the clogging of pumps
Entangled material due to sanitary items can generally be prevented only if they are shredded or pass through a grinder prior to reaching the pump. One economic variant for reliable protection from clogging of pumps and wastewater pipelines are twin-shaft grinders. These wastewater grinders are designed based on a contactless principle of operation, which is why their power requirements during idle running is minimal. Thanks to low speeds, large torques are made available for grinding, enabling these devices, even with a low drive power, to prevent the clogging of pumps or wastewater pipelines. For many operators, the investment in a technique of this type pays for itself within a very short time. Electricity consumption and hence operating costs of the pumps drop, sparing cost-intensive maintenance and service visits, as well as emergency maintenance at nighttime or on public holidays to free up entangled material in the pumps.
One important aspect when using wastewater grinders in the sewer system is harmonization with downstream technology. The grinding process must be fine enough for the shredded fragments to pass through pumps and valves without any problem. At the same time, fragments must remain large enough so that they can be reliably separated by downstream screens and not enter the sewage treatment plant. In order to guarantee this, various cutting tools are required. XRipper’s ripper rotorsare manufactured from a single piece, resulting in long service life and other considerable benefits when compared to systems consisting of individual cutting blades and spacers. Besides a wear-resistant, hard surface, they offer better force transmission with a minimized risk of breakage due to foreign matter like metal parts, etc.. And thanks to the narrow tolerances, the grinding process is more efficient and less drive power is required.
An important criterion when selecting a wastewater grinder for the protection of pumps and screens is a high level of availability and operational readiness. Instances where the entire shredder needs to be removed and even sent away for replacement of parts are counterproductive. This is particularly the case when an overhaul might take several weeks. This is why the XRipper wastewater cutter is designed for our QuickService concept: All service and maintenance work can be performed by your own staff on site in a short time without any long interruptions to service.
Where sufficient space is available, we recommend the conventional design of the XRipper XRS. Its construction enables service and maintenance work to be performed directly on site without removing the grinder from the wastewater pipeline. Stainless steel versions specially for chemically aggressive wastewater are also available.
Often however, space is at a premium, particularly if a wastewater grinder is to be retrofitted in a narrow shaft. For such cases, the XRipper XRP has been developed with the motor positioned above the shredder. This concept enables efficient grinding in the wastewater current on a minimal surface area. Installation is simple and inline in the wastewater pipeline, requiring just a minimal flange-to-flange space. And importantly for many operators, service and maintenance work can be performed on site here too. for this the drive unit is simply raised up out of the housing, which itself remains fixed in the wastewater pipeline via screws.
One suitable place for shredding all wet wipes and other interfering substances before they enter the pump or screen is directly in the open wastewater sewer, which is why the concept of the XRipper XRC has been harmonized for this application. The entire shredder is simply placed in the sewer. Since service and maintenance work in the sewer is not possible, or only with difficulty, the entire wastewater grinder is simply lifted out of the sewer. Using a special rail system, the Sewer Integration Kit (SIK), XRC can also be positioned directly before inlets or outlets of wastewater pipelines, open gutters and sewers, or inflows and outflows of chutes – without the need for any fixation work. Simply insert, lower – and shredding of disruptive wipes, cloths etc. can commence. This protects the pump and avoids failures due to clogging and service interruptions.
High flow rates, such as those occurring in large sewers and inflows of sewage treatment plants, can only be mastered with appropriately large yet efficient shredders. The XRipper XRG was developed specifically for these applications. The sieves of the High Capacity Units arranged laterally in the housing permit large quantities of (waste) water to pass by unhindered, while catching and holding back the disruptive matter and waste. This is continuously fed into the Ripper rotors which reduce them to a manageable size. For removal of the functional unit just remove a couple of screws on the housing is all that is required.