Solids handling in wastewater applications has become increasingly challenging. The combination of low-flow appliances and water conservation at large, along with the rise of “flushable” media, has resulted in much higher solids-to-water ratios. This puts a strain on pumps and other equipment. In particular, solids such as wipes can get stuck on equipment, causing damage and sending operators scrambling to clear jams or initiate repairs. Traditional solids handling methods are still effective but in many cases are no longer the best solution.

Traditional solids handling systems are most effective in low-pressure installations. The large openings allow large solids, including rag balls, to pass through. However, in many regions, it is increasingly common for high-head, low-flow pumps to feed into high-pressure force mains. In these types of installations, large solids passages in the impeller can be a detriment, resulting in excessive vibration that can shorten the lifespan of the pump. Operating high and to the left of the performance curve requires a pump designed to handle that sort of application.

Advancements In Chopper Pumps

While chopper pumps are not a new technology, recent advancements have made them more adept at handling the rising levels of solids in high-pressure, low-flow installations. For example, HOMA Pump Technology developed its OC impeller specifically to address this and several related problems. The OC impeller uses integrated cutters: a stationary cutter and a sharp-edged cutting plate attached to the impeller (Figure 1). The newly designed impeller can perform up to 7,000 cuts per minute and boasts several advantages over other chopper pump designs.

Figure 1. The OC impeller uses a stationary cutter and rotating cutting plate. Both components work together to catch and break down challenging solids. Integrated grooves in the cutting plate remove solids from the suction area.

Increased cutting surface

To prolong the duration of the cut, rather than using a single straight edge, the OC impeller’s stationary cutter is curved, increasing the surface area of the cut. Similarly, the rotating cutting plate is also curved in a spiral-like back sweep. Altogether, it significantly increases the amount of time the cutter has to work through difficult solids.

Durability

In order to handle high solids content and high pressure, durability of components is paramount. To accomplish this, HOMA uses high-chromium white iron. This provides a balance of hardness without being too brittle, allowing the blades and impeller to stand up to abrasion and other abuses it will face over its lifespan.

Low maintenance

Several features on the OC impeller aim to reduce maintenance over time. For example, the impeller and cutting plate are both made of the same durable white iron, which has high wear resistance. However, as wear occurs, the tolerance of the cutting surfaces can be changed with a simple adjustment of three set screws. This also allows for a three-dimensional lean of adjustment as needed. In addition, the high chromium content of the white iron means it is corrosion resistant, which further reduces the need to replace parts.

Standard pump features

HOMA pumps featuring the OC impeller boast the same standard features as its more established pump series. This includes an explosion-proof motor, cooling jackets, and more.

The Right Fit For Tough Applications

As mentioned, the OC impeller is designed with low-flow, high-pressure installations in mind. In addition to municipal wastewater treatment plants, effective applications could include:

Food processing

Large-scale food processing operations often have to treat high solid-content wastewater. Even if the plant does not have to treat the wastewater before disposing it, some operations may need chopper pumps to reduce the risk of clogs caused by fibrous matter such as corn husks, as well as bones, tendons, and more.

Nursing homes

Medical care professionals have come to rely on disposable and “flushable” wipes and other material, particularly in the wake of COVID-induced changes to care and sanitation procedures. This, plus the increased use of personal protective equipment, makes already difficult wastewater even more challenging.

Correctional facilities

Under the best of circumstances, prison wastewater has high solids content owing to the large number of adults using the same infrastructure for kitchen waste and human waste. However, efforts by some residents to intentionally sabotage wastewater systems means correctional facilities need robust and reliable solutions that can handle a wide range of solids that are placed into the waste stream, including blankets, pillows, books, plasticware, and more.

Rely On Service

When considering a chopper pump for a wastewater solution, it is important to consider customer service. No two installations are the same and any number of factors can affect equipment performance. The right supplier should be both proactive in addressing potential problems and also responsive when unexpected challenges arise. HOMA Pump prides itself on being a partner and helping resolve challenges throughout the life of a product.