When people think of the bottom line, they’re factoring in their expenses versus their revenue. Wastewater treatment plant owners usually think about the “triple bottom line” (TBL). The plant’s bottom line covers more than financial aspects. They also must think about the world and community they’re part of. The TBL theory covers:

• Environmental
• Financial
• Social

With a TBL theory, they’re maximizing revenues, protecting the environment, and making the people in their district happy. As a plant manager, you have to carefully work within the municipality to ensure the water treatment steps provide safety for your workers, meet the EPA’s guidelines for water before it goes back into the environment, keep costs down for the community, and meet the increasing flow rates. That is your TBL, and a grit removal system is a vital part of meeting your bottom line.

What Is a Grit Removal System?

Grit includes abrasive materials like coffee grounds, sand, gravel, and small bone fragments. To get them out of a wastewater treatment plant’s equipment, you need to have machines that wash, collect, and remove the gritty particles. Why bother?

Wastewater and stormwater runoff contains gritty materials that impact the performance of valves and pumps. Imagine the impact of sandpaper rubbing back and forth on rubber, plastic, or metal all day, every day. It would wear out in little time. The same is true of your wastewater treatment plant’s valves and pump components.

All of this grit also builds up in lines, channels, and tanks, which reduces flow rates and capacity. To resolve these costly issues, a grit removal system is imperative.

Grit removal systems are set up to filter wastewater and storm runoff as it comes into a treatment plant. How it does this job depends on the equipment. A vortex, aerated, or circulating system stirs or pumps air into the water. The idea is to get the grit to sink to the bottom, where it is pumped into equipment to be rinsed and moved to containers for removal.

• Aerated Grit Chambers – Pump air into the water to stir it up so that heavy grit sinks to the bottom.
• Cyclonic Grit Chambers – Water enters in a way that forms a cyclone that pushes heavier grit to the bottom.
• Horizontal Flow Chambers – Water flows horizontally to allow heavier gritty materials to sink.
• Vortex Grit Chambers – Paddles stir the water to allow oils and fats to rise to the surface while grit sinks to the bottom.

The system you choose depends on your plant’s size and needs. Some grit removal systems take more space than others. If you have a small plant, a larger piece of equipment might not fit your needs. You also must consider your flow rates, capacity, and amount of grit that’s typically in your municipalities’ wastewater or stormwater runoff.

How Does Grit Removal Help You Meet Your Bottom Line?

How does removing grit help your bottom line? Think about the amount of wastewater and storm runoff that come into your treatment plant. The average person uses upwards of 100 gallons of water daily with showers, laundry, oral hygiene, dishes, and toilet flushes. A wastewater treatment plant often has thousands of people in its district. The median number of gallons that are treated in a wastewater treatment plant each day is around three million.

Of those three million gallons, the average amount of grit is upwards of 45 cubic feet. Imagine all of that grit rubbing against the components in pumps and valves. If it’s not filtered out early in the process, it can cause costly damage. Not only are you paying for new components to make the repairs, but you’d also have the machine’s downtime for the repairs. That cuts into the financial component of your TBL.

When you remove grit, you make your district members happier. You’re not wasting money on frequent repairs and replacements caused by damage from the grit. You’re also protecting the environment by ensuring your equipment is doing its job and preventing the accidental release of raw sewage caused by equipment failures.

Lakeside Equipment’s Options for Grit Collection and Removal Systems

Whether you need to replace old, ineffective grit collection and removal systems or want to add efficient equipment to your wastewater treatment plant, Lakeside Equipment has a selection of options for you. Take a closer look at your choices.

Aeroductor Grit Removal System

The Aeroductor Grit Removal System uses air to move the water vertically to allow grit to settle to the bottom of the grit hopper. Grit is pumped out using an airlift pump, dry-pit vortex pump, or self-priming pump. Benefits are:

• Aeration helps kickstart the treatment process.
• Energy costs are lower.
• Flow rates don’t matter.
• Grit comes out cleaner as it’s separated and dewatered simultaneously.
• No parts are underwater, and no buckets, chains, or augers are needed, so maintenance is easily managed.

H-PAC

H-PAC combines the Hydronic T Screen and SpiraGrit Vortex Grit Chamber. It screens trash and grit at the same time at rates of up to 12 million gallons per day. It doesn’t take a lot of space, making it a popular choice in smaller plants. Benefits include:

• It costs less due to the pre-engineered design.
• Multiple screen options meet your exact needs.
• Stainless steel construction helps with corrosion prevention.

In-Line Grit Collector

With the In-Line Grit Collection, flow rates of 0.25 to 6 million gallons per day are possible. It works by having wastewater come into one end of the tank, flow under a baffle, and pass over a weir. Grit sinks to the bottom of the tank, where a dewatering screw dewaters it and moves it to an awaiting dumpster. Benefits include:

• It’s an easily-installed and cost-effective grit removal system.
• Maintenance costs reduce as there is little mechanical equipment and no buckets or chains.
• The screw conveyor doesn’t wear out due to the grit, and a direct drive speed reducer also lowers maintenance and repair costs.

SpiraGrit Vortex Grit Removal System

The SpiraGrit Vortex Grit Removal System is designed for sites with limited space. It’s ideal for fluctuating daily flow rates. It works by having paddles stir the flow in a vortex chamber. Organics remain suspended while the grit sinks to the bottom to be pumped using an airlift, recessed propeller, or self-prime pump. From there, it goes to a Grit Classifier or Grit Washer. Benefits include:

• Bearings are all above water for easy maintenance.
• The grit chamber head loss is minimal.
• Impressive grit removal rates regardless of the flow rates.
• Stainless steel construction is available to prevent corrosion.

You also want to consider a Grit Classifier and Raptor Grit Washer. Grit that comes from wastewater soaks up some of the water. To collect that water, you want to invest in a grit washer or grit classifier. These systems work to remove water from the grit slurry.

A Grit Classifier spins the slurry in a cyclonic pattern to force the grit against the chamber’s walls while the water leaves through the overflow pipe. The screw pumps with this system are designed to resist wear. Upgrade to stainless steel construction to prevent corrosion.

Raptor Grit Washers work similarly, using centrifugal force to remove water. It can get the grit to a dry rate of 90%.

Reach out to Lakeside Equipment to learn more about the options for grit removal. Find out how the right grit removal equipment will help you meet your wastewater treatment plant’s bottom line.