The wastewater you treat contains more than organic materials. Cinders, gravel, sand, and other heavier solids are also found in wastewater. This grit must be removed if you’re going to prevent clogged piping and abrasive damage to the equipment. If grit isn’t removed, it moves on to aeration tanks and digesters where it impedes the treatment process.

Grit Removal Methods

You have wastewater to clean and grit removal is one of the first steps towards clean water. What are your options? Several methods are available for grit removal. Take a look at the options you’ll encounter when discussing the equipment for your water treatment plant.

Aerated Grit Chambers

In an aerated grit chamber, air is pumped in on one side, which forces incoming wastewater into a spiral flow. As the water flows, the heavier grit falls to the bottom of that tank while lighter organic materials and water continue to the exit. Energy use is higher with an aerated grit chamber. Maintenance costs can also be higher in this type of system.

Detritus Tanks

Detritus tanks are square in design and have to be followed with grit washing to remove the organic materials that get trapped in the grit that’s removed. Augers and rakes are typically used to remove the grit, which means electricity will be running and driving up energy consumption. The rake arm can also agitate the wastewater and stir up some grit and lead to some of it escaping as wastewater flows out. It’s also harder to control flow rates when you use a detritus tank.

Horizontal Flow

Horizontal flow grit chambers are one of the older types you’ll come across. Wastewater enters the horizontal chamber and flows through several small dam-like areas (weirs) that trap grit while the water keeps moving from one area to the next. Grit is removed using scrapers. Flow rates can be harder to control with this system, and headloss is also a concern. The equipment may wear faster, too.

Hydrocyclones

Hydrocyclone systems find wastewater being pumped into the grit chamber and the cyclone force traps the grit and solids on the sides and bottom where they’re removed. The benefit is that both grit and solids are removed at the same time. If you do not screen wastewater before the grit removal process, the hydrocyclone system will run into issues with solids like plastics, rags, and sticks.

Stacked Trays

Some water treatment plants use stacked trays. This system has several trays stacked in a round chamber. Water comes in at the top and circulates over each of these trays. Grit falls to the bottom chamber while the water flows out the other side. Grit is then removed from that lower chamber. While stacked tray systems do not always need electricity, they can be cost-effective, but the depth of the system requires excavation that can be costly. Headloss can also be a concern.

Vortex Systems

Vortex grit removal technology may seem similar, but it’s not. There are differences in technology that you need to consider to ensure you’re getting optimal grit removal and efficiency. One area where vortex grit removal is similar is that wastewater flows into a circular tank. With that tank is a mechanical rotor that creates a vortex that can slow down or speed up depending on flow rates.

Paddles rotate to stabilize the flow velocity. This keeps organic particles suspended within the wastewater while heavier particles of grit sink to the floor. At floor level, the vortex pushes grit to the center where it moves into a grit hopper. From there, it travels to the grit classifier by being pumped, airlifted, or pushed out through an impeller. Grit is washed in the grit classifier to remove any remaining organics. The final step is to move it to trucks, hoppers, or dumpsters where it goes to a disposal facility or landfill.

Vortex systems are popular due to the space that’s needed for installation, the effectiveness, and the overall cost. You should put a vortex grit chamber at the top of your list.

How Effective Are Vortex Grit Chambers?

You’ve narrowed down your choices for vortex grit removal systems. Two of the leading options are the Smith & Loveless Pista Grit Removal System and Lakeside Equipment SpiraGrit^® Vortex Grit Removal System. The Smith & Loveless Pista Grit comes in several models that are capable of removing up to 95% of the grit in your wastewater. Pista Grit uses a hydraulic design with a flat chamber floor and propeller that creates the vortex. This propeller doesn’t require a lot of energy, so it can be a cost-effective grit removal system. You choose if you want the system to be baffled or not.

Lakeside Equipment’s SpiraGrit^® Vortex Grit Removal System allows you to choose a few things. It’s also an energy-efficient model where it adapts to a range of daily flow rates. Paddles keep the vortex flow moving steadily, so organics float to the top while heavier grit moves downward to the bottom where it falls into a grit hopper and is pumped out using a self-priming pump, airlift pump, or impeller. At that point, you can have the grit move to Lakeside Equipment’s Grit Classifier or the Raptor^® Grit Washer as the next step.

Why is the Lakeside SpiraGrit^® Vortex Grit Removal System the Ideal Choice?

Lakeside’s SpiraGrit^® Vortex Grit Removal System has one of the highest removal efficiencies on the market. It doesn’t matter what the flow rate is, this grit removal system does an exceptional job in a compact size. Head loss rates for the SpiraGrit^® Vortex Grit Removal System are also low. You don’t need a lot of space for the SpiraGrit^®  Vortex Grit Removal System. It’s designed to be efficient and compact. It’s also designed to separate grit and perform dewatering at the same time, which adds to the efficiency.

If you’re worried about high maintenance costs, don’t worry. There are no submerged bearings. This grit removal system is easy to maintain. You can also have the SpiraGrit^® Vortex Grit Removal System crafted from stainless steel to prevent corrosion.

A Headworks Packaged System Covers Everything You Need

With Lakeside’s H-PAC system, you get the SpiraGrit^® Vortex Grit Chamber within a full headworks system that’s capable of flow rates of up to 12 million gallons per day. Start with the Raptor^® Screen that removes, washes, and dewaters items it captures on the screens. From there, the pre-screened wastewater enters the grit chamber where fine particles of grit are removed. This protects equipment used later in the wastewater treatment process.

For more than 90 years, Lakeside Equipment has provided solutions for treatment plant designers and engineers. Lakeside’s experience with water purification and water treatment processes cannot be matched. Our engineers will design a system that meets your needs and matches your budget. Our goal is to design a system that is built to last, and should you ever need parts, we have a stellar parts department who are happy to help you.

Choose Lakeside’s H-PAC^® system with the SpiraGrit^® Vortex Grit Chamber for a cost-effective, highly efficient grit removal system. It doesn’t require a lot of space, so you don’t have to worry about having a lot of room available for your grit removal needs. For more information on how you can achieve Lakeside quality and performance, contact one of our experts at 630-837-5640, email us at sales@lakeside-equipmnet.com or visit our website www.lakeside-equipment.com

Most people look at wastewater treatment and sewage treatment as being the same thing. They are, but it’s not that easy. While there are similarities, sewage treatment is a part of the wastewater treatment process. It’s handled differently. To understand the differences, it helps to understand precisely what wastewater is.

Why does it matter? The overall wastewater treatment process has to clean the water of chemicals, food particles, and grit. It also has to remove human waste, which is where sewage treatment comes in.

Wastewater Contains Black Water and Gray Water

Wastewater is made up of black water and gray water. These two types of wastewater go to the same facility for treatment, but they’re different and require different steps. Start by understanding the differences between gray water and black water.

What’s black water? Every toilet flush goes into the sewer lines or the private septic system. The water from that toilet is called black water. It’s human waste, water, and toilet paper.

There may be cleaners, too. People may have bleach tabs, toilet sanitizers, and other toilet cleaning products. While it shouldn’t contain additional items like wrappers, menstrual pads, and other trash, sometimes it does.

Gray water is the other part of wastewater. Gray water comes from dishwashers, washing machines, showers, sinks, and bathtubs also goes into those sewer lines and septic systems. It’s the water from washing things, but it also contains cleaners like soap, shampoo, and detergents. There’s also grease from washing dishes by hand or in a dishwasher.

Industrial firms may have gray water from running machines. For example, a company that extrudes plastic may run water over the materials to quickly cool or set the plastic coatings. The water will have the chemicals and small particles of plastic, so it can’t simply go back into a body of water. First, it has to be cleaned.

You also have dairy treatment plants, food processors, and breweries that add to the wastewater mix. They all release wastewater that contains high levels of biological and chemical pollutants that add additional strain on wastewater treatment plants. Municipalities need to carefully plan their wastewater treatment system to handle the wastewater that’s received.

What’s in Wastewater That Has to Be Treated?

Wastewater and sewage contain a variety of components that have to be treated. Here are the different things that are treated during wastewater and sewage treatments.

• Inorganic Materials: Inorganic materials include metals and minerals. How do they end up in wastewater? They leach from pipes that carry water, and they come from cleaning products.
• Nutrients: You also have nutrients like nitrates, nitrogen, and phosphate. If you live near a lake with algae blooms, that’s the result of too many nutrients winding up in the lake water. The nutrients cause the algae to flourish, which uses up oxygen that the aquatic life relies on.
• Organic Matter: Organic matter, like food particles, are also common. You wash dishes, and small pieces of food go down the drain. They rot and can cause harm if they end up in ponds or lakes because they use up oxygen to help the organic matter decompose.
• Organisms: There are several organisms found in wastewater. If a pet owner flushes the cat’s waste in the toilet and that waste has roundworms in it, you now have roundworms in the wastewater. Bacteria and other microorganisms are also found in it.
• Pathogens: Plants must kill bacteria, parasites, and viruses to remove them from wastewater before returning to homes, businesses, or bodies of water. These pathogens include things like cholera, E. coli, and norovirus. When COVID-19 hit, wastewater treatment plants were finding that virus in wastewater, too.

How Gray Water is Handled at a Wastewater Treatment Plant

Wastewater comes into a treatment plant through sewer lines or at a septage acceptance plant. If the wastewater is being trucked in, septic trucks drive up to the septage acceptance plant and unload the materials pumped from septic systems into the facility.

Pretreatment occurs as wastewater enters the treatment plant. Here, screens catch debris and trash from the wastewater. It goes to the grit removal, which is equally important. If sand and gritty particles get into pumps and valves, it can damage that equipment and lead to costly repairs or replacements and valves.

Wastewater treatment plants may use self-contained units that take care of the screening and grit removal at the same time. The Raptor Complete Plant is ideal for the pretreatment of septage and wastewater from the sewer lines. You can add a grease trap to it to help remove extra grease before the primary treatment begins.

From the grit chamber, wastewater goes to a clarification tank to start primary treatment. The wastewater sits for several hours to allow solids to sink to the bottom of the tank. Grease floats to the top, where it’s skimmed away. Scrapers keep moving over the bottom so that the sludge is transferred to pumps and removed from the wastewater.

The wastewater starts going through the secondary treatment process. Oxygen is added to the leftover water to help stir it up and get oxygen to begin breaking down any particles of waste or organic materials that didn’t sink to the bottom. Again, the wastewater moves to a clarification tank to allow the remaining sludge to settle, get scraped to pumps, where it goes to sewage treatment.

Tertiary treatment is the third step. Chemicals are added to remove phosphorus from the remaining wastewater. Chlorine is used to help kill bacteria that remain after the other two treatment steps. Water goes through filters and may be exposed to UV rays to remove the chlorine before the water returns to bodies of water or storage tanks.

How Black Water is Handled at a Wastewater Treatment Plant

The sludge that’s removed from clarification tanks goes through sewage treatment. Anaerobic digesters break down the sludge, and carbon dioxide and methane are removed and captured during that process. That biogas can be used to provide electricity and heat.

What happens to the fecal matter that’s left behind? It varies from one area to the next. It could be dried, ground, and turned into fertilizer. Anaerobic digestion removes bacteria, so it’s safe to use. Workers move the remaining sludge to trucks where it’s sent to a landfill to become part of the soil. It could also be incinerated. If it’s burned, the methane gas can heat the wastewater treatment plant, which is a cost-effective option for many municipalities.

Careful Planning Creates a Comprehensive Wastewater Treatment Plant

When deciding on the equipment a wastewater treatment plant requires, it’s important to know how much wastewater flows each day. Some hours will have a higher flow rate than others. When people get home from work, have dinner, do dishes, and take baths and showers, the wastewater flowing into the sewer lines increases.

You need to consider where the wastewater is coming from. If you have breweries that lack their own wastewater treatment systems, you’ll have a lot of extra wastewater coming in on brewing days. It’s essential to plan for these increases. Plant managers need to be prepared for the increases.

One of the easiest ways to do this is by hiring an expert to design your wastewater treatment system. Talk to Lakeside Equipment. With close to 100 years in the business, we can help you develop a system that treats both wastewater and sewer water. We work closely with you to help you stay on budget without cutting corners and ending up with an inefficient system.