Monthly Archives: October 2018

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.