How Does A Wastewater Treatment Plant Work?

According to the Environmental Protection Agency (EPA), wastewater treatment is one of the most common forms of pollution control in the U.S. Lakeside Equipment Corporation is proud to supply equipment and systems that are used across the country at wastewater treatment plants, which are facilities that clean wastewater before discharging it back into the environment.

The Need For Wastewater Treatment Plants: Then and Now

Wastewater treatment plants were not always necessary. In the past, bacteria and other organisms found in waterways would break down sewage into harmless byproducts in a naturally occurring purification process. But, the bacteria and other organisms could not keep up with the increase in population and production of sewage. Wastewater is now sent to wastewater treatment plants—many of which use the same purification process found in nature to clean water.

Most wastewater treatment plants prepare wastewater for reuse in two separate stages: the primary and secondary stage.

The Primary Stage of Wastewater Treatment

Sewage enters the primary stage of treatment as soon as it arrives at a wastewater treatment facility. First, it is sent through a screen that is designed to remove large pieces of debris that could damage Lakeside equipment used elsewhere in the facility. Some facilities have multiple screens in place to remove objects and materials of different sizes from the sewage.

After passing through the screen, the sewage water moves into the grit chamber. Grit can include sand, gravel, eggshells, or any other type of solid material that makes it through the screening process. There are several different types of grit chambers, but Lakeside’s aerated grit chamber is among the most popular. The wastewater flows in a spiral pattern inside this chamber. Air is slowly introduced into one side of the chamber, creating a perpendicular pattern that separates heavier materials from the rest of the water. The heavier materials, or grit, then sink to the bottom of the chamber.

Even though the wastewater has been through screens and a grit chamber, it still contains other materials that need to be removed. The wastewater slowly flows through a sedimentation tank, and as it flows, the solids that remain in the water start to drift towards the bottom of the tank.

This is the final step in the primary stage of the wastewater treatment process. At this point, the majority of the solids have been removed from the water. But, the water is still not clean enough to be released back into the environment, so it enters the secondary stage so it can be purified even further.

The Secondary Stage of Wastewater Treatment

The secondary stage of the treatment process is designed to remove up to 85% of organic matter that remains in the wastewater. There are a number of different ways to achieve this goal, but many facilities use either the trickling filter or activated sludge process.

If the facility uses the trickling filter method, the wastewater is pumped into an area that contains between three to six feet of stones after leaving the sedimentation tank. Bacteria and other small organisms grow on these stones, so they consume or break down the organic matter in the water as it flows through the tank. The water is then removed from the trickling filter through pipes and sent back to a sedimentation tank for yet another round of purification.

Most facilities use the activated sludge process, which takes place immediately following the sedimentation tank in the primary stage of treatment. The wastewater enters an aeration tank, where it is mixed with sludge. Air is then pumped into the aeration tank to facilitate the growth of bacteria and other small organisms within the sludge. The bacteria and other microorganisms break down the organic matter in the water into harmless byproducts. The wastewater will remain in the aeration tank for between three to six hours, which gives the bacteria and microorganisms plenty of time to break down all of the remaining organic material. After leaving the aeration tank, the wastewater is usually sent to another sedimentation tank to separate the solids from the water.

Regardless of which method is used, the wastewater will go through one more round of treatment before it is released back into the environment.          After the water leaves the sedimentation tank in the secondary stage of the treatment process, it is sent into tanks where it is exposed to chlorine. Wastewater typically spends between 15-20 minutes inside these tanks with chlorine. This chemical kills the harmful bacteria that could be lurking in the water, and it also gets rid of the unpleasant smell of wastewater. Wastewater treatment plants can kill up to 99% of bacteria in water with chlorine, so this is an important step in the process.

Some facilities do not use chlorine to kill bacteria in the final stage of the treatment process. Instead, these facilities use alternatives such as ultraviolet (UV) light or ozone to kill bacteria in the water before releasing it to the environment. These alternatives do not involve the use of chemicals, so they are considered safer for the environment and wildlife.

After the water is sent through this final stage, it is released into waterways in the community. The final stage ensures that the vast majority of bacteria in the water is killed so it will not harm humans, animals, or the environment once it has been discharged.

Treating wastewater is a complex process that involves the use of high-tech and reliable equipment. Lakeside is proud to supply the equipment and purification systems that wastewater treatment plants need to filter, clean, and disinfect water before it is sent back into local waterways.  If you are interested in purchasing Lakeside equipment or systems, speak to one of our representatives today by calling 630-837-5640.

How Does the Biological Wastewater Treatment Process Work?

There are two main types of wastewater treatment: primary and secondary. Primary treatment is a fairly basic process that is used to remove suspended solid waste and reduce its biochemical oxygen demand in order to increase dissolved oxygen in the water. It’s estimated that primary treatment only reduces biochemical oxygen demand by about 30% and suspended solids by up to 60%. Therefore, the water needs to be treated again in order to remove additional contaminants.

Secondary treatment involves complex biological processes that are used to remove organic matter that was not removed during primary treatment. There are many different kinds of biological wastewater treatments, however each treatment can be classified as either an aerobic or anaerobic treatment depending on whether or not oxygen is present.

What Are Biological Aerobic Treatments?

If a treatment is classified as a biological aerobic treatment, it means it takes place in the presence of oxygen. Aerobic treatments work faster and result in cleaner water than anaerobic treatments, which is why they are preferred.

The most popular aerobic treatment is the activated sludge process. At the start of the activated sludge process, wastewater moves into an aeration tank that is pumped full of oxygen. Aerating the wastewater increases microbial growth, which speeds up the decomposition of the organic matter that is still in the water. Then, this wastewater is transferred into a secondary clarifier, which is also known as a secondary settler or settling tank. The sludge, or waste, within the water will start to separate, leaving only the clean and treated water behind. This is one of the most efficient ways to biologically treat wastewater.

Another popular aerobic treatment is the trickling filter process. During the trickling filter process, wastewater flows over a bed of rocks, gravel, ceramic, peat moss, or plastic. As the wastewater flows, the microorganisms in the water quickly start to attach to the bed. A layer of microbial film will soon start to grow over the bed. Over time, the aerobic microorganisms found in this layer of microbial film will start to break down the organic matter found in the water. If needed, oxygen can be infused or splashed into the wastewater to maintain aerobic conditions.

The trickling filter process can rapidly reduce high concentrations of organic matter in the water, however there are disadvantages to this method as well. A trained professional will need to watch over this process from the start to finish, so this may not be the best choice for facilities with limited resources. Clogs are also fairly common, so the trained professional will need to know how to identify and fix this issue.

Some facilities use aerated lagoons as opposed to the activated sludge process. With this method, the wastewater sits in a treatment pond, where it is mechanically aerated. Pumping oxygen into the pond will increase microbial growth and speed up the decomposition of organic matter. However, unlike the activated sludge process, the water is not moved into another tank after it has been aerated. Instead, the separation of the sludge and the clean water happens within the treatment pond.

Using an oxidation pond is another way to biologically treat the wastewater. This process involves removing the organic matter from wastewater using an interaction between bacteria, algae, and other microorganisms. This method may seem similar to an aerated lagoon, but it is far more complex and it takes much longer to achieve the desired results. This process also requires a lot more land space than the others, so it is typically not used in areas that are densely populated.

What Are Biological Anaerobic Treatments?

Biological anaerobic treatments take place in the absence of oxygen. Aerobic treatments are usually preferred, however it is best to use an anaerobic treatment when dealing with highly concentrated wastewater.

The upflow anaerobic sludge blanket reactor is a single-tank anaerobic treatment, which means it takes place in one tank. This process begins with the wastewater entering through the bottom of the reactor tank. As the wastewater naturally starts to flow upwards, it encounters a sludge blanket that is suspended within the tank. The sludge blanket consists of microbial microorganisms that break down organic matter within the wastewater. When the wastewater encounters the sludge blanket, the microorganisms quickly break down the organic matter, leaving clean water behind to rise to the top of the tank. There are other similar anaerobic treatments, including the anaerobic filter, which involves a filter that has microbial microorganisms on its surface.

What Happens After Wastewater is Biologically Treated?

It’s estimated that biological treatments can remove up to 90% of the wastewater’s contaminants. Because all of the contaminants have not been removed, the wastewater is usually sent through a tertiary treatment process after the biological treatment. During this stage, heavy metals, nutrients, and other impurities are removed from the wastewater.

The most common type of tertiary treatment involves the use of chlorine, which is a powerful disinfectant. Small amounts of chlorine are added to the water to remove the remaining impurities before the water is discharged into the environment. There are other ways to disinfect the water that do not involve chemicals. Many facilities avoid the use of chlorine by using UV light to treat the water. Regardless of which method is used, it is estimated that about 99% of all contaminants have been removed from the wastewater after it has completed this treatment.

Since 1928, Lakeside Equipment Corporation has been committed to providing clean and healthy water to people around the world using innovative biological treatment processes. Contact Lakeside Equipment Corporation to learn more about our biological treatment systems. Call 630-837-5640 or visit our website to connect with one of our knowledgeable representatives today.

How Do Hydropower Trash Rakes Work?

The importance of removing contaminants from wastewater cannot be understated. If wastewater is not properly treated before it is returned to the environment, it could harm the environment or negatively impact the health of people in the community.

The wastewater goes through a lengthy treatment process that involves a number of different steps. Early on in the process, the water is pushed through a screen, which filters out large pieces of debris. The debris must be cleaned off of these screens periodically, otherwise the screens will be less effective. To clean these screens, it’s best to use a trash rake.

What is a Trash Rake?

Trash rakes are heavy devices that are used to remove large pieces of debris from screens at hydropower facilities. Most trash rakes are designed with long arms that reach into the bottom of the basin. The arm of the trash rake then moves upwards across the screen, picking up pieces of debris along the way.

Some trash rakes simply drop the debris that is collected on a nearby deck so it can be manually removed by workers at the facility. Other types of trash rake move the debris away from the deck and drop it into a bin designated for this type of waste.

What Are Cable Operated Rakes?

There are two main categories of trash rakes: cable operated rakes and hydraulically operated rakes. A cable operated rake system consists of a cable winch and rake arm. The rake arm scrapes across the screen to remove large pieces of debris, which is then deposited in a dumpster.

The Catronic Series trash rack sits on the deck located above the screens. It can be used as a stationery unit to clean a single screen or as a moving unit that is capable of cleaning multiple screens. Another cable operated rake system is the Monorail Series trash rake. Instead of sitting on the deck, this type of trash rake moves back and forth along a monorail structure that is built above the screens. Because it moves along the monorail, this trash rake can be used to clean multiple screens within the same general area.

There are benefits to both the Catronic Series and Monorail Series trash rake systems. One benefit of the Monorail Series trash rake is it does not take up space on the deck, whereas the Catronic Series trash rake does. Both of these systems use low maintenance energy efficient equipment that can easily be repaired and cleaned away from the water that is being treated. The install for these raking systems is easy, too. This means facilities can install either one of these systems without having to replace their existing screens or make any other modifications.

What Are Hydraulically Operated Rakes?

Lakeside’s hydraulically operated rakes are ideal for hydropower plants, pumping stations, wastewater treatment plants, and other industrial applications.

The Hydronic T Series trash rake system features a telescoping design that can clean at inclinations of up to 90 degrees. This system can run without the use of chains, guides, and sprockets, which makes it easier to operate. The pressure that the rake applies to the screen can also be adjusted to minimize the wear and tear.

The Hydronic K Series trash rake system is designed with a long arm that can reach depths of up to 100 feet. The arm is also capable of removing larger objects from the water such as trees and rootstocks. Depending on your facility’s needs, the K Series system can remain stationary to clean a single screen or it can swivel or travel to reach other screens.

Another hydraulically operated raking system is the Hydronic Multifunctional (M) Series. The M Series is designed with an articulating arm and a telescoping rake that can reach depths of up to 150 feet. There are several different rake heads that can be used on this system, including a triple jaw gripper that is capable of lifting more debris, and an orange peel grapple that is ideal for removing debris from the bottom of the screen.

Although this system can be semi-automatic or fully automatic, there is also the option of manually operating it out of the driver cab. It is best to manually operate the system to remove large pieces of debris from the surface.

Finally, there is the Hydronic H Series trash rake system. The other systems mentioned above are designed to clean screens that feature vertical bars. However, the H Series trash rake system is specifically designed to clean screens with horizontal bars. This rake starts at one side of the screen and pushes the debris caught between the bars to the other side of the screen. Then, the debris that has been collected can either be removed manually or with a grab rake.

Self-Cleaning Screens

Trash rake systems are used to clean screens, however it’s important to note that there are also self-cleaning screens available. The CO-TEC screen, for example, is designed with rake teeth that can be extended between the bars on the screen. Once extended, the rake teeth can then be lifted upwards, dragging debris in the same way that a trash rake does. If the screens at a facility need to be replaced, this type of product should be considered. However, facilities that are not interested in replacing their existing screens should stick to a trash rake system instead.

To learn more about hydropower trash rakes or to place an order, contact Lakeside Equipment Corporation today. Lakeside Equipment Corporation has been committed to improving the quality of water resources for decades. We currently provide high quality products and reliable services to municipalities and companies around the world. Call 630-837-5640 or visit our website to connect with one of our knowledgeable representatives today.

Centrifugal Pumps vs. Positive Displacement Pumps

The pumps that are used to treat wastewater can be classified as either a centrifugal or positive displacement pump. There are pros and cons to both of these types of pumps, so it’s not always easy to determine which one is right for your needs. To make the right choice, it’s important to learn the differences between centrifugal and positive displacement pumps.

How Centrifugal and Positive Displacement Pumps Operate

To understand how these pumps are different, you must first learn how each pump operates. Positive displacement pumps draw a fixed volume of liquid into the pump through the suction valve, trapping it within a cavity found inside the pump, then forcing it out through the outlet valve. The manner in which the liquid is forced out through the outlet valve will vary depending on the type of positive displacement pump. For example, a piston positive displacement pump is designed to force liquid out using a piston that moves up and down through the body of the pump. Other positive displacement pump models, such as screw pumps and gear pumps, do not have components that move up and down. Instead, these pumps use rotating components to force liquid from one side of the pump to the other.

Centrifugal pumps are known for their simplistic design. The most important component of a centrifugal pump is the impeller, which is a rotating device that moves fluid through the pump. The impeller rotates to draw fluid into the pump, then transfers kinetic energy from the motor to the fluid, which moves through the pump and exits through the discharge valve.

How Pressure Affects the Flow Rate

One of the main advantages of a positive displacement pump is its ability to produce a consistent flow rate. The flow rate of a positive displacement pump will remain constant when there are changes in pressure.

However, this is not the case with centrifugal pumps, which are designed to react to changes in pressure. The efficiency of a centrifugal pump peaks at a specific level of pressure. Whenever the pressure is not at this specific level, the efficiency of this pump will decrease. Therefore, the flow rate of centrifugal pumps will be affected by changes in pressure.

How Viscosity Affects the Flow Rate

Another difference between centrifugal and positive displacement pumps is the way the viscosity of the fluid affects the flow rate. As viscosity increases, the flow rate of a centrifugal pump will begin to rapidly decrease. The exact opposite is true of positive displacement pumps. As the viscosity increases, the flow rate of a positive displacement pump increases as well. This is because highly viscous liquids quickly fill the internal clearances of a positive displacement pump, which produces a greater volumetric efficiency. For this reason, it is important to choose a positive displacement pump to handle liquids that are highly viscous.

Shearing of Liquids

The speed of the spinning impeller found within the centrifugal pump design makes it less than ideal for handling shear sensitive mediums. Positive displacement pumps are not designed with any high-speed components, which means these pumps will not apply a great deal of shear to mediums. Because of this, it is best to choose a positive displacement pump when handling mediums that are shear sensitive.

Suction Lift Capabilities

Some centrifugal pumps will have suction lift capabilities, however the standard models do not. Positive displacement pumps do have suction lift capabilities. Consider the piston pump, which is a traditional positive displacement pump model. The piston is the component that moves up and down to force water from one side of the pump to the other. When the piston moves upwards, the pressure in the body of the pump goes down, which will open the suction valve and allow water to flow freely into the pump. The suction valve will close when the piston moves downward and increases the pressure inside the body of the pump, which pushes the water out of the pump.

When to Use Centrifugal and Positive Displacement Pumps

When choosing a pump, it’s important to consider the conditions in which the pump will operate. It is best to use a centrifugal pump to handle a large volume of low viscosity fluid in a low pressure environment. The centrifugal pump works best when it is transferring water, however it can also handle the transfer of low viscosity chemicals and fuels.

Because of its simplistic design, centrifugal pumps can be made out of a number of different materials, including plastic, stainless steel, and cast iron. This makes it more versatile since its design can be adjusted to fit your needs. This type of pump is also very compact, which makes it the ideal choice when there is not much space for a pump.

Positive displacement pumps are often installed to pump oil, sewage, and slurry. Positive displacement pumps are also ideal for pumping fluids that contain solid materials. In general, positive displacement pumps are used whenever the conditions are not ideal for centrifugal pumps. For example, the flow rate of a centrifugal pump is greatly affected by changes in pressure. Therefore, it is best to use a positive displacement pump when there will be changes in pressure, since this will not impact the flow rate of this type of pump.

To learn more about centrifugal and positive displacement pumps or to place an order, contact Lakeside Equipment Corporation today. For decades, Lakeside Equipment Corporation has been committed to providing high quality and reliable products and services to customers around the world. Let us guide you through the process of finding the right centrifugal or positive displacement pump for your needs. Call 630-837-5640 or visit our website to connect with one of our knowledgeable representatives today.

Open vs. Enclosed Screw Pumps

For decades, engineers have used screw pumps for wastewater plant lift stations, storm water pumping, and other industrial applications. These pumps are used to move large volumes of liquid, but their design also makes it easy for large objects to pass through without clogging the system. This means water that is contaminated with various objects can be pumped with ease.

Screw pumps can also be operated when no water is present. This means there is no need to install additional parts to stop the pump from running in dry conditions. The pump can continue to operate regardless of how little water is present.

Screw pumps are not only efficient, they are also low maintenance. The pumps are designed with very few moving parts, and these parts constantly run at a slow speed. This innovative design minimizes wear and tear and the need for repairs.

Screw pumps can be used in a variety of industrial settings. However, there are two main types of screw pumps that engineers must choose between: open and enclosed. Before placing an order, it’s important to understand the differences between these two designs.

An Introduction to Open and Enclosed Screw Pumps

Before learning about the benefits of both open and enclosed screw pumps, it’s best to learn the differences between their designs.

An open screw pump has four components: a spiral screw, upper bearings, lower bearings, and a drive assembly. Open screw pumps are placed within concrete or steel troughs at a slight angle, leaving their screw-shaped design exposed.

Enclosed screw pumps are very similar to open screw pumps, however they are encased within a tube so their screw-shaped design is not exposed. Because the pump lies within a tube, it does not need to be placed within a cement or steel trough.

There are two types of enclosed screw pumps: Type S and Type C. Both of these types are enclosed within tubes, however the tube in a Type S design is stationary, whereas the tube in a Type C is not. Type C pumps are designed with two spiral flights welded to the inside of the pump’s tube, which rotates as it operates.

The Benefits of Open Screw Pumps

The open screw pump is known for its simplicity and reliability. These pumps are incredibly low maintenance as it is, however they can become even more durable. If the lower bearing is designed with a permanently greased lubricated roller bearing or a sleeve bearing, this will minimize the wear and tear even further.

If a repair is needed, it may be easier to identify the issue on an open screw pump than it would be on an enclosed pump. This is because the open design of an open screw pump makes it possible to see all of the moving parts.

The bottom of an open screw pump can operate in both submerged and non-submerged conditions, which makes it more versatile than other screw pumps.

The Benefits of Enclosed Screw Pumps

As previously mentioned, enclosed screw pumps are encased within a tube, which eliminates the need for a steel or concrete trough. Because it does not need a trough, it is considered easier to install than an open screw pump. It’s also a better choice for clients who are in need of a quick replacement and do not have the time to install a trough.

Both open and enclosed screw pumps are efficient, however the Type C pump operates at the highest efficiency. In fact, it is estimated that the Type C pump is between 5-10% more efficient than the open screw pump, which is why it has become a popular choice.

The Type C enclosed pump has a maximum inclination of 45 degrees, whereas the open screw pump and Type S enclosed pump both have a maximum inclination of 40 degrees. The difference between 40 and 45 degrees may not seem significant, but it results in the Type C enclosed pump leaving a much smaller footprint.

There are benefits to the Type S enclosed screw pump, too. The top of Type S enclosed pumps can be fixed in place or mounted onto a pivot. If it is mounted onto a pivot, the tube can be repositioned to adjust the pumping rate. Both the open and Type C designs do not have this flexibility.

How to Choose the Right Type of Screw Pump

There are benefits to both open and enclosed screw pumps, which can make it difficult to determine which is right for your needs. Instead of focusing on the design of the pump, think about how the pump will be used. These are the factors that should be taken into consideration when selecting a screw pump:

  • Capacity
  • Speed
  • Inclination
  • Number of Flights
  • Horsepower

For example, the number of flights in a screw pump will have an impact on the output capacity of the system. This is because each additional flight increases the output capacity of the pump by about 25%. Therefore, it’s important to calculate the maximum output capacity needed so you can determine how many flights you will need. By approaching the decision in this manner, you will be able to select the perfect open or enclosed screw pump for your needs.

To learn more about open and enclosed screw pumps or to place an order, contact Lakeside Equipment Corporation today. At Lakeside Equipment Corporation, we are committed to treating water so it can be used as drinking water or safely returned to the environment. Since 1928, we have provided local governments and corporations with the high quality services and top-of-the-line equipment they need to help us achieve this goal. Call 630-837-5640 or visit our website to connect with a representative today.

Roanoke VA Treatment Plant Uses Lakeside Equipment

Roanoke, Virginia Regional Water Pollution Control Plant treats 37 million gallons of wastewater a day. From 2015 to 2016 they had a major upgrade and expansion to their facility. New screw pumps were added for peak wet weather flow pumping when the Roanoke wastewater treatment capacity is exceeded.

The screw pumps elevate the un-treated wastewater to a flow equalization tank for off-line storage. The stored un-treated wastewater is later returned to the wastewater plant for treatment after the peak flow subside. The 114-inch screw pumps are some of the largest in the U.S.

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Screw Pumps provide a cost-effective and reliable method of pumping large quantities of water at low total dynamic head (TDH).

Create Positive Cash Flow from Septage Treatment Systems

A treatment plant frequently can easily add a septage receiving station to create a valuable source of revenue while also providing a needed service to the community and surrounding businesses. A wide range of features are available, but it all starts with a well-designed receiving system, built to handle a variety of hauled waste. The Lakeside Raptor® Septage Acceptance Plant and Raptor® Septage Complete Plant leads the industry for liquid hauled waste receiving systems and can be tailored for your unique needs.

Six Potential Sources of Materials

  • Septage waste, generally consistent and predictable in character.
  • Grease trap waste, typically high in oils and grease from restaurants.
  • Waste activated sludge from other treatment works.
  • Industrial waste, highly variable from one industry to another; these wastes must be tested for toxicity in the process and most likely require pretreatment.
  • Landfill leachate, potentially toxic often requiring additional testing and pretreatment.
  • Portable restroom waste, typically high in ammonia and total nitrogen, and often containing bottles and other large objects.

John Olson, P.E., a regional sales manager with Lakeside Equipment Corporation, described the essential features of septage acceptance stations. “The septage acceptance plant requires a heavy-duty design,” Olson said. “It should be fully automated so haulers can come in, swipe a card, and discharge their load. The decision to accept any hauled material becomes the plant operators’ responsibility. Therefore, the basic design should be customized to their needs.”

For more details on how to leverage your treatment plant to generate revenue for your organization and help to defray maintenance costs, provide needed upgrades and meet compliance requirements, check out the attached article or contact us

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