Why is a biological wastewater treatment process so important? Every gallon of water brought to a wastewater treatment plant is contaminated. If it comes from a residential septic tank, it’s filled with urine, feces, and dirty water from laundry, dishes, and showers/baths. The same is true for water that is piped in from sewers. Even industrial wastewater is going to contain contaminants.

It’s important to properly clean water before releasing it into natural water sources. Too much phosphorus can cause algae blooms to take over the lake or pond. Algae will end up depleting the stores of oxygen fish and other aquatic creatures rely on. As many lakes are becoming overrun with blue-green algae, states are all taking measures to limit the chemicals, minerals, and bacteria by making sure water treatment plants meet requirements that remove these items from water.

Primary vs. Secondary Treatments

Before this water returns to lakes, streams, or public water systems, it has to be cleaned and disinfected. That’s done through several steps that include biological wastewater treatment, but there are also primary measures. You have screens that remove items that won’t break down. Many of these items should be trashed, but it doesn’t always happen. People don’t realize the problem it’s posing when they flush things that aren’t meant to be flushed. Tampon applicators, plastic wrappers, toy cars, and baby wipes are just a few of the things that make it to a wastewater treatment plant.

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. Primary is the use of screens and trash rakes to remove larger items. It’s also the grit removal system.

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. That’s where secondary treatment comes in.

Secondary treatment involves complex biological processes that are used to remove organic matter that was not removed during primary treatment. You’re using biology and microorganisms to devour and remove other contaminants. There are many different kinds of biological wastewater treatments, however, each treatment can be classified as either an aerobic, anaerobic, or anoxic treatment depending on whether or not oxygen is present. Here’s a quick look at the three.

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. Aeration is needed to oxygenate the wastewater through the use of mixers and aerators. 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. Remaining sludge can then be converted into a mixture of methane and carbon dioxide that can be used for heat and electricity. Any remaining sludge is dewatered (dried) and composted or sent to a landfill. The activated sludge process is one of the most efficient ways to biologically treat wastewater and it’s effective.

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, coconut fibers, 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 About Biological Anoxic Treatments?

You also have anoxic treatments. In this case, the microorganisms use other molecules to multiply. There may not be oxygen, but nitrates and nitrates act in its place. Anoxic treatments help remove nitrates and nitrites, selenates and selenites, and sulfates from the wastewater.

People are seeing this more in areas where nitrates and sulfates are a concern. It’s the best way to remove as many of them as possible. Anoxic treatments work without adding additional chemicals.

While many states stopped using laundry detergents that contained phosphates, you still see shampoos and soaps with sulfates and nitrates. High levels of sulfates can give water an unpleasant taste and can be dehydrating. High levels of nitrates can impact how oxygen moves around the bloodstream. While it takes a lot to affect a person’s health, it’s still important for water districts to make sure water is safe for everyone.

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. Once the chlorine is at safe levels, the water can be released back into water sources or moved to storage tanks that supply homes and businesses with water.

What Equipment Is Needed?

The equipment that’s needed for biological treatment systems depends on the area and load. A large city processes far more wastewater than a small town. Systems may want to put a lot of focus on being energy efficient. So many have strict discharge restrictions that must be adhered to. Take a look at some of the equipment that’s used in biological treatments.

#1 – Closed Loop Reactor (CLR) Process

The CLR Process is ideal for its consistency and performance whether you’re in a cold climate or a warm one. It’s designed in a closed loop like a circle or extended oval like you’d see at a race track. Aerators and multi-basin designs complete the system. Because this system is customized for simple, effective operation, it can handle increased loads with ease and doesn’t require a lot of attention from workers in a wastewater treatment plant.

Not only can you save money with the CLR Process, but it also helps lower energy costs. It’s adept at removing phosphorus and nitrogen. If you need a system that works well at cleaning water without driving up costs for the members of your district.

#2 – Extended Aeration/Complete Mix Process

An economical solution biologically processing of wastewater is a package treatment plant. It’s a smaller design that’s ideal when space is limited. Choose an E.A. Aerotor Plant or a Packaged Extended Aeration Plant. What are the differences?

An E.A. Aerotor Plant uses the design from a CLR Process for aeration and mixing and a Spiraflo Clarifier to help the sludge settle. The addition of oxygen in the aeration/mixing process aides biological processing and helps remove more sludge. You add other components as needed to create a custom wastewater treatment design.

You could choose the Package Extended Aeration Plant to have an all-in-one system in a single steel tank. It is designed for low usage and includes your screens, aeration, clarification, sludge tank, and disinfection in one. You don’t need a lot of manpower to effectively operate this system.

#3 – Sequencing Batch Reactors

Treat wastewater in one basin using the Sequencing Batch Reactor or Continuous Feed Sequencing Batch Reactor. This system works by aerating and mixing wastewater to create a lot of oxygen. It then “decants” so that the water is discharged without needing activated sludge pumping or external clarifiers. It allows biological wastewater processing to process for an extended period.

#4 – Magna Rotors

If you’re relying on a system that does add oxygen to help with biological wastewater treatment, Magna Rotors are one of the leading choices. Think of them as large mixers that add oxygen. The benefit is that the rotors have a fiberglass cover that does not get too cold in the winter. You’re not as likely to see the equipment stop working in the winter. The stainless steel blades are also durable and not likely to become bent or dented.

#5 – SharpBNR Process Control

This is an add-on that can help with overall energy consumption and performance. The process control can be programmed to measure things like dissolved oxygen and aeration. Adjust them as needed to meet your goals using a computer or the Human Machine Interface on the control panel. You can link it to a SCADA system, too.

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.

Every corner of the country has been impacted by the coronavirus pandemic. Across the nation, there have been more than 5.75 million cases of COVID-19 and more than 177,700 deaths. It’s alarming to think of how fast this virus has spread during 2020. One area people don’t think about is the impact of COVID-19 on wastewater treatment.

While it might not be something you stop to consider, COVID-19 has impacted the wastewater treatment industry, too. It’s affected wastewater treatment in several ways ranging from increased residential wastewater to clogged pipes and equipment. There’s also the fact that the body does shed the virus through the waste that ends up in the wastewater traveling through sewer lines and into residential septic systems.

The CDC and the U.S. Department of Health and Human Services have started a surveillance program to track the levels of COVID-19 in wastewater. While no one has found evidence of the virus spreading through wastewater (treated or untreated), the virus is present in the feces of those who have the virus. By studying patterns, experts know where they should be looking for COVID-19 clusters and making testing available.

The other reason it’s important for wastewater treatment plants to test for COVID-19 is to keep workers safe. Employees who work in wastewater treatment plans should take protective measures with personal protective equipment and safe practices at work. Doing so can eliminate the risk of contamination from untreated wastewater.

Problems With Clogged Lines and Equipment

One of the problems wastewater treatment plants are facing with the pandemic has been trash in the sewer lines. Around the nation, wastewater treatment plants are facing issues from a large increase in protective gloves, masks, and disinfecting wipes making their way into sewer lines and wastewater treatment plants. People are flushing these items instead of disposing of them in the trash as they should.

Most toilet papers disintegrate in water. It usually takes no more than 24 hours. Wet wipes don’t break down as quickly. They may flush and make it through toilet pipes, but as they travel through the sewer, they can catch on tree roots, curves, and other items and collect other items. Soon, there’s a huge blockage of fat, feces, napkins, tampons, and wipes that isn’t breaking down. It slows down the wastewater’s flow and can lead to sewer backups and spills.

As the pandemic started, toilet paper stocks decreased. Soon, toilet paper shortages were affecting everyone. People were turning to baby wipes, makeup removers, and any other moist wipe they could use in place of toilet paper. Napkins and paper towels were other items people were using in place of toilet paper. Rather than throw them into the trash, as they needed to, they were flushing them. These items do not break down quickly. They were causing clogs in sewer lines and water treatment equipment.

Latex or non-latex gloves and disposable masks were other items getting flushed. Again, they don’t degrade in water, so they were clogging lines. In Washington, a bill was signed making it illegal to flush non-flushable wipes starting on July 1, 2022. In Tennessee, one town’s sewer workers started cleaning sewer pumping stations twice a week instead of once a month. An Air Force base in California has crews working 16-hour shifts to remove clogs from pipes. In Maryland, one wastewater pumping station saw an increase of more than 37,000 pounds of wipes during the first quarter of 2020.

All of this is costing cities and towns a fortune in additional hours and repairs. People need to remember to only flush toilet paper and human waste. Despite the pleas from one side of the nation to the other, people keep flushing things that cause harm. That’s one of the biggest ways the pandemic has impacted wastewater treatment. Grinder pumps and screens are essential to handling all this increased trash, but not every district has the money available to install them.

Increased Wastewater Flow in Residential Areas

With more people working from home, residential water consumption has also increased. A water monitoring company studied water usage and found it increased by about 21% per day. Some cities saw higher increases. For example, New York City’s residential water consumption increased by 28%. In Minnesota, the increase was 25%. People working from home are doing more laundry, using the toilet more, washing more dishes, and taking more showers. People are also washing hands more as is recommended by the CDC.

This increase in water usage means wastewater treatment plants are treating an increase in water. Water treatment plants that treat a lot of water from commercial industries may see decreases, but water treatment plants serving mostly residential structures are facing large increases that older equipment may not be able to handle.

Another change with water usage is when peak water usage is happening. It used to be that most families showered and ate breakfast in time to catch buses/trains and commute to work or school. Families had to have kids ready to get on the bus for the early morning pick-up. Commuters had to be out of the home early to beat rush hour traffic. Wastewater treatment plants expected the highest water flow around 7 a.m. and again around dinner time or 6 p.m.

Without the rush to commute or get to a bus or train, people shifted their morning routines an hour or two later than normal. Peak water usage is now around 9 a.m. instead of 7 a.m. Water treatment plants expect changing flow rates throughout the day and may use computers to speed up or slow down equipment accordingly. Not every plant is set up this way, however. Changes in flow rates at unexpected hours can cause problems. If treatment plants have flow rates that are higher than anticipated, they may have to ask residents to avoid running appliances during certain hours to reduce the strain on older equipment that cannot keep up.

Does Water Treatment Kill Coronavirus?

People who get their residential and commercial water from treated water do not have to worry about the virus still being present. Wastewater treatment processes kill viruses and bacteria. After filtering wastewater, aerating it, and using chemicals to kill any residual contaminants, water that’s returned to bodies of water or put into storage tanks for public water systems. No evidence of COVID-19 surviving water treatment has been found.

What if untreated wastewater makes it into lakes or streams after heavy rains? There is the chance that COVID-19 will be in untreated water, but there has not been any known case of the virus spreading through wastewater spills. Wastewater treatment plants should do everything possible to prevent untreated wastewater spills by making sure their system can handle an increased capacity and repair broken equipment and lines.

Can steps be taken to eliminate the chances of COVID-19 untreated wastewater from returning to the environment? How can plants anticipate changes in peak water flow? What can be done to stop people from flushing their gloves, masks, and wet wipes? Upgrading equipment is key. Older infrastructure needs to be improved to reduce energy consumption and keep up with changes in wastewater flow rates and screening.

Lakeside Equipment is here for districts that need to repair their equipment due to damage from items that shouldn’t be flushed. We can also help districts upgrade equipment to be more energy-efficient or handle an increase in residential wastewater as people are working from home and cooking more meals at home. Reach us by phone or email for more information on a new wastewater treatment system or to discuss upgrades that will save your district money.

It came out in May that the worldwide market for positive displacement pumps is forecasted to reach $11.25 billion in the next seven years. That’s almost double the market’s value in 2019. Why are these pumps high in demand? What’s driving the increased need for this specific type of pump? There are several factors.

It helps to understand what positive displacement pumps are used for. They remove liquids from discharge pipes. They’re useful in many industries including wastewater, food and beverage, oil and gas, mining, etc. If you have liquid or fluid matter that needs to be moved from Point A to Point B, a positive displacement pump is your answer. Take a closer look at how these pumps help in these industries, what you should look for, and how they work.

A Guide to How Positive Displacement Pumps Work

Pumps move liquids or fluid materials from one area to another. There are axial-flow pumps fluids in one direction. Liquids come in passes through an impeller and travel out the other end. A centrifugal pump changes the flow by using a motor and impeller to create energy that pushes fluids along. The final option is a positive displacement pump that captures an amount of fluid and forces it into the discharge pipe. The benefit is the pump handles a constant volume even if the pressure changes.

These pumps are categorized by their mechanisms:

1. Linear-type: Chain or rope pumps
2. Reciprocating-type: Diaphragm, piston, plunger, or radial piston pumps
3. Rotary-type: Gear, hollow disk, rotary vane, screw, or vibratory pumps

A linear-type of positive displacement pump uses a chain or rope and some form of a plate or even bucket to displace liquids. Go back in time to an ox-powered water wheel. Oxen were tethered to the big wheel and walked in circles. That motion moved the wheel, which moved the chain or rope along a pulley or up and down a drilled or dug well to collect water from deep within the well. Back up at the surface, the motion at the top of the pulley system dumped the water into a discharge chute while the buckets made a new path. Today, they’re more likely to have a chain and disc system that fits within a tube or pipe. As the discs are pulled up through the tube or pipe, water is trapped and is drawn upward.

Next up is a reciprocating type. How it works depends on the type. Think of the old-fashioned well pump. People pumped the handle and each upward pull of that handle drew water up to the discharge pipe. There’s also a piston pump that also uses the upward pull or downward thrust to move liquids. A diaphragm pump is the other type of reciprocating pump. An air bladder (diaphragm) moves up to decrease pressure or down to increase pressure. If you have a private well, you have a pressure tank that helps water flow from the well to the different water lines within the home.

The final main type of positive displacement pumps is the rotary type. There are five types of rotary positive replacement pumps: gear, hollow disk, rotary vane, screw, or vibratory. Screw pumps are one of the types of pumps you’ll encounter a lot in water treatment plants, which makes them one of the more familiar types. You can have an open or enclosed screw pump. They work by having a giant screw within a closed or open chute or pipe. The blades of that screw capture the fluid from a lower pool of liquid, and the motion of the turning screw propels it upwards and to the top of that chute or pipe.

Screw pumps are popular in so many industries and settings. It’s worth stopping to talk about them. You have open and closed. Open is in a concrete trough, and enclosed is in a steel tube. For enclosed screw pumps, there are the Type C or Type S. Type C pumps have two flights (screws) that are welded into the rotating tube. Type S works oppositely with a stationary tube.

While the mechanics vary, the goal of any pump is the same. The mechanics draw in the fluid material on one side, move it through to the next with the help of motors or human or animal power. For the most part, you’ll be relying on motors to power these pumps. If energy-efficiency is vital to your water treatment plan, home setting, or business, you should look at solar-powered or wind-powered electricity to run your pump.

Their Role in Different Industries

That’s the breakdown of the different types of positive displacement pumps. How are they used in different industries? Getting back to the increased need for positive displacement pumps in the next seven years, a driving force in this is going to be the need to find new options for energy. Natural gas is in high demand and is just one of several hydrocarbons that are drawn from the earth using positive displacement pumps. Because drilling and fracking require a lot of pressure, piston pumps that handle the high-pressure situation are often used.

As some look for environmentally-friendly ways to heat their homes and businesses, hydrocarbons aren’t the first choice. Solar and wind power are one choice, but there’s one that is gaining popularity. Geothermal energy needs powerful pumps to move the water from below ground into the building.

You can use these pumps in a geothermal system. Geothermal energy takes the natural warmth found within the earth and uses it for home heating. You pull the warmer water from deep within the ground where it releases that warmth into the house and discharges the cooled water in a continuing cycle. In the summer, geothermal energy helps keep the house cool. The surface temperature is warmer than the temperature deep in the earth. The cooler water is drawn into the home to cool the air and discharges the warmer water back in the ground to cool again. A positive displacement pump can help keep that flow of water from the underground to the building from coming to a stop.

In water treatment, these pumps move the wastewater from the sewer lines or septage station to the next steps in the treatment process. Screw pumps are the common option in a waste treatment plant. If solids like fat balls or fecal matter won’t mess up the screw pump. They’ll move to the next steps where the sludge is separated for processing. Sludge eventually ends up in disposal tanks where it can be dried and composted or taken to a landfill. More homes and businesses mean more of a load. To meet the increased load, water treatment plants are upgrading and increasing capacity. They’re adding energy-efficient measures to lower overall costs. This all starts by choosing the right pumps and water treatment equipment.

In a rice paddy or other agricultural settings where irrigation is needed, positive displacement pumps move water from another water source to your fields or rice paddies. In rural settings, a tractor may be attached to a chain using a chain pump. In a large commercial field that grows everything from corn to wheat, irrigation systems need to be efficient and move a lot of water every day. These settings may use screw pumps to move water from a lower pond or water tank to the elevated fields. Liquid manure needs to be pumped into trucks for spreading.

Pumps also serve a need in the food industry. A plant that makes sausage needs a way to pump the mix of ground meat and spices into the machines that fill casings. A viscous mixture like pasta sauce needs to be transferred from the vats where it’s cooked into machinery that jars it. Food grade screw pumps do this without breaking down as the acidic sauce passes through the pumps for hours at a time.

How Do You Shop for a Positive Displacement Pump?

What are your needs? Archimedean screw pumps don’t clog and can move the liquids and solids wastewater treatment plants handle. Screw pumps are used in sludge pumping, effluent lift stations, and stormwater management. They can help drain land or move water from a water source to elevated fields. Screw pumps are used to move grain in an agricultural setting. They’re also helpful in moving liquids around in wineries and breweries. While your budget is important, it’s also important to have a clear vision of what the pump will do. Do you need the pump that can process foods or one that will be exposed to the outside elements?

You also need to have a clear idea of where the pump is going so that you get the right size. An enclosed screw pump takes up less space than an open screw pump. A Type S screw pump may take up more space because it has a pivoting end. The pump needs to keep up with the flow rate without causing a backup. How much space is there? If there are space limitations, you need to choose a pump that is the right size for the space you have.

Maintenance is the third factor to weigh carefully. Motors in a pump need to be lubricated or they’ll seize. Some units are designed to be maintenance-free, others require a little more care. How much staff and/or time do you have for upkeep? Do you want to make sure bearings are lubricated after months or years of use or do you prefer the idea of self-contained lubrication that is always there? A Type E Sealed Bearing requires little to no maintenance, and if re-lubrication ever is needed, it’s not time-consuming as you never have to remove the bearing.

Do you have time to clean the components, or should the pump be designed to prevent clogs or build-up? A clog-free design is one of the factors that make Lakeside Equipment’s screw pumps the best choice when it comes to maintenance and cleaning. Screen rakes also help keep trash from getting to your equipment.

Choose a specialist in water treatment and hydropower equipment. Lakeside Equipment’s expertise dates back to 1928. We make sure your goals are met by talking about your budget, space, and district. If you’re in an area where the population growth is rapid, a design that considers that growth is important. If you’re looking for equipment that cuts electricity costs, we can help there, too. Give us a call to learn more about Lakeside’s positive displacement pumps.