HeadCell® Myths Debunked
Over the years we’ve seen a wide variety of myths pop up about the HeadCell® wastewater grit removal system. We’re not sure where they came from, but they can all be easily debunked.
When you’re the best performing grit removal system on the market, people get jealous. It’s natural—we get it. Unfortunately, rather than making better systems, some manufacturers prefer to rely on convincing others that their system works just as well as the HeadCell® stacked tray grit, sand and solids separator. This is usually done through misleading and confusing performance claims and skewed measurements intended to obscure the truth.
To put it simply, most—if not all—of these claims are just not true.
With good science, independent testing, and the testimonies of countless delighted customers, we can help you get to the truth and assess the real quality and performance of the HeadCell® system for yourself.
The bottom line is that nothing works better than HeadCell®.
The myths
> Myth: “HeadCell® performance is derated at peak flows”
> Myth: “HeadCell® needs a deep tank”
> Myth: “HeadCell® is expensive and difficult to install”
> Myth: “HeadCell® requires a lot of energy to operate”
> Myth: “HeadCell® requires more water to operate”
> Myth: “HeadCell® does not capture grit down to 75 micron”
> Myth: “Plastic trays lead to wear issues”
> Myth: “HeadCell® might capture down to 75 micron, but there’s no such claim for the washing and dewatering equipment”
> Myth: “HeadCell® has significant headloss”
> Myth: “HeadCell® is prone to plugging, and is difficult to maintain”
> Myth: “HeadCell® works just as well with other manufacturer’s washing and dewatering systems”
Myth: “HeadCell® performance is derated at peak flows”
Reality: Our systems are designed specifically to meet your performance criteria. When you purchase and install a HeadCell® system—indeed, any Hydro International grit management system—you know exactly what performance your grit system will provide, at all flows.
The reality is that there’s always a balance between the frequency of your peak flows and the impact your plant would actually realize. We can certainly supply a system that captures virtually everything at every flow, but many of our clients decide that the cost-benefit ratio is not significant enough to warrant oversizing a system to meet infrequently encountered flows. So, rather than "derating" performance as is claimed, we in fact match the performance with the customer's actual requirements.
We appreciate that striking the right cost-benefit balance can be difficult, which is why our applications engineering team is always on call to help you select the perfect size system to meet your plant’s needs.
Myth: “HeadCell® needs a deep tank”
Reality: “Deep” is a very subjective term (intentionally, we suspect), so this is an odd one to address.
When we work with you to specify your grit removal system we’ll be absolutely clear about how much space or depth a HeadCell® unit will require—and how much space you could save.
Surface area is the governing operating principle in any type of grit separation system, and HeadCell® is extremely flexible in order to give you that surface area while maximizing the use of your existing infrastructure. The number of trays and tray diameters can be adjusted and scaled to meet your plant’s specific layout and performance requirements, so if minimizing footprint is your key driver, a deeper tank supplies a massive amount of surface area in a tiny footprint. However, if depth is an issue then shallower tanks can be used with smaller tray stacks in parallel to give you the performance your plant needs. HeadCell®’s uniquely flexible design options allow you to maximize the use of your existing infrastructure, channels, and tankage.
While the HeadCell®—with the ability to place up to 12 trays in a single unit—can indeed be situated in a deeper tank to significantly reduce the required footprint, it doesn’t need to be; that’s entirely up to you.
Myth: “HeadCell® is expensive and difficult to install”
Reality: Not only is HeadCell® not expensive to install, it also saves money over the lifetime of the system.
Unlike many conventional systems, which require long approach channels or complicated concrete arrangements, the HeadCell® wastewater grit removal system has a noticeably shorter approach and is placed into what is essentially a square tank. A simple grout cone at the bottom of the unit is all that's needed, and we provide simple instructions to the contractor to ensure the most straightforward installation.
With such a large amount of surface area in such a small footprint, you can minimize the tankage needed for grit removal, eliminating the need for a large amount of complicated concrete work—this reduces overall construction costs significantly.
The HeadCell® arrives on site pre-assembled in stacked tray modules, conveniently pre-configured to easily hoist and stack on top of one another; these tray stacks can then be connected with nothing more complicated than a socket wrench. With no moving parts or complex mechanical elements, the HeadCell® is in fact extremely easy to install.
In most cases, not only does HeadCell® cost significantly less to install than inferior conventional grit removal technologies, but it also requires a smaller footprint, and delivers better performance than any other type of grit removal system.
Myth: “HeadCell® requires a lot of energy to operate”
Reality: We're not exactly sure where this one came from, but this is one of the easiest myths to disprove. The HeadCell® itself has no internal maintenance-intensive moving parts, and requires no electricity to operate. The system runs entirely through hydraulic forces, and less than a foot of headloss is needed to “power” the HeadCell® at all flows.
The system is also available in an intermittently operated configuration, which further reduces energy costs for the grit washing dewatering system by only operating as needed. When an intermittent HeadCell® is paired with a Hydro GritCleanse™ combined washing and dewatering system, the entire grit washing process can operate at very low energy and with low levels of non-potable water.
While it's true that the PLC control panel and grit pump require electricity to operate, as well as things like actuators, motors, and solenoids on the dewatering system, these electrical needs are common to most all types of grit removal systems. Taking into account these common factors, HeadCell® based grit removal systems typically require a much lower amount of electricity than other grit removal systems (or, in the closest cases, comparable electrical consumption).
Myth: “HeadCell® requires more water to operate”
Reality: One reason this myth has arisen is because of a persistent lack of understanding about how wastewater grit behaves. We understand how grit behaves in the real world, and as such we work with plant owners and operators to ensure that they achieve optimal grit capture, and keep their systems operating smoothly under even the heaviest grit loading during wet weather events.
Using water keeps grit fluidized, and prevents it from packing in the grit sump; water is also necessary to produce clean grit for disposal. Therefore appropriate water use improves operations and produces a cleaner end product.
HeadCell® doesn’t need more water to operate—though we do offer low consumption options for plants that wish to lower their water use—but in our experience many plants have an abundance of available non-potable water, and they prefer to use that water to improve their operations.
Myth: “HeadCell® does not capture grit down to 75 micron”
Reality: This is another one that's easy to debunk, along with the related myth that our system performance is derated to 85% at peak flows.
We suspect that, again, this myth might have arisen due to inadequate understanding of wastewater grit behavior: since grit removal efficiency is a sedimentation process, and therefore a function of surface overflow rate, all grit systems will remove more grit at lower flows and less grit at higher flows.
This doesn't affect our performance claim, however. To put it bluntly, our guarantee of 95% removal of all grit 75 micron (2.6 SG) and larger means what it says: 95% removal of all gradations 75 micron (2.6 SG) and larger.
We don’t try to fabricate performance or value that’s not present. That's how we can continue to offer the best performance guarantee in the industry with HeadCell®.
Myth: “Plastic trays lead to wear issues”
Reality: Some people might erroneously think that a material like polyethylene might be unsuitable to withstand the abrasive impacts of grit. As a low-velocity unit, however, HeadCell® trays experience none of the wear issues that casual observers might expect; we’ve had HeadCell® systems operating continuously for decades, with no signs of wear on the trays.
More durable materials like steel aren't necessary, and in fact bring with them some very significant downsides. When continuously submerged in wastewater over time, even the highest grades of steel will experience erosion, corroding, rusting, and pitting; over time, this can lead to severe problems with blockages, as things like rags and strings get caught on these rough edges, and these are incredibly difficult to clean.
Additionally, as the metal degrades the efficacy of the surface area contact is also degraded, and as a result excessive organics will be captured along with the grit. And hopefully we don’t need to mention that stainless steel is significantly more expensive than plastic.
Sure, we tried metal—decades ago—but we quite quickly discovered that it was a terrible idea to use in this application. The fact is, plastic trays are robust, they work, and they're cost effective.
Myth: “HeadCell® might capture down to 75 micron, but there’s no such claim for the washing and dewatering equipment”
Reality: We’re not sure where this came from, as our SlurryCup™, TeaCup®, Grit Snail® and Hydro GritCleanse™ grit washing and grit dewatering systems will absolutely retain 95% of grit 75 micron and larger.
Furthermore, we're willing to back that with a guarantee.
That's why it is so important to have your entire grit removal system supplied by a single manufacturer. With single-supplier accountability you know exactly what you'll be getting throughout the entire grit removal process.
Myth: “HeadCell® has significant headloss”
Reality: This is a strange one, as it's so obviously and demonstrably untrue—it's a quick, easy one to dispel.
HeadCell® is a low-energy forced vortex system, with no moving parts, which operates entirely on hydraulics. Less than a foot (30 cm) of headloss is needed to run even the largest HeadCell® system at all flows.
Myth: “HeadCell® is prone to plugging, and is difficult to maintain”
Reality: Requiring no power and with no moving parts, HeadCell® is an extremely low-maintenance technology. We recommend conducting an inspection twice a year, which only requires draining and spraying down the tank to visually inspect the system.
With the typical 1/2” (13 mm) screening prior to flows entering the HeadCell® unit we have only encountered plugging a handful of times over hundreds of installations—and all of these cases were due to underperforming screening systems or improper operation of the grit system.
In this handful of cases our world-class service people have always acted quickly to resolve the issue swiftly, in some cases with as little as a phone call to advise the plant on adjusting its methodologies to improve operation.
Myth: “HeadCell® works just as well with other manufacturer’s washing and dewatering systems”
Reality: All of our equipment is designed to work as a complete grit removal process consisting of separation, washing, and dewatering, and each technology in the grit removal chain is specifically designed to complement the performance of other steps in the system.
While you can substitute alternative or inferior washing and dewatering technologies, you can never be sure of the actual performance. With single-supplier accountability, you can be confident in knowing that the entire grit removal system will perform to your required specifications—and if you ever need to talk to anybody then there's only one call you need to make.