Nitrogen is one of the worst pollutants as it increases algae blooms in streams, rivers, and lakes. It gets into the ocean and hurts coral reefs, seagrass, and plants, developing fish and aquatic animals. Plus, algae blooms can harm wildlife and pets that swim in or drink the polluted water.
Current estimates are that around 6.2 million tons of nitrogen make it into the world’s oceans and seas. The Mississippi River is one of the largest offenders in the U.S. with around 1.57 million metric tons of nitrogen released into the Gulf of Mexico each year.
Here’s something you should be prepared for, especially if your city or town has an aging wastewater treatment plant. Prepare to have the EPA order you to lower the amount of nitrogen being released into nearby water sources. With polluted lakes, streams, rivers, and coastal waters, it’s past time to make changes to stop the damage. That’s why the EPA is cracking down.
It Could Happen to You, Too
This happened to Chicopee, Massachusetts, recently. Chicopee’s sewer department received notice that they must lower the nitrogen the city releases into the Connecticut River. At the time of the warning, the city was releasing around 1,800 pounds per day and needs to reduce that to no more than 647 pounds. The cost of the upgrades needed to meet the EPA’s requirements is topping $65 million.
That’s just one project the city is currently working on. They also are working on separating the stormwater runoff and sewer systems to prevent heavy rains from flooding the wastewater treatment plant or backing up the sewers and ending up dumping raw sewage into area rivers. That project is estimated to cost the city about $300 million when it’s completed.
So far, the city has received a grant for $4.5 million, but the costs of all upgrades are expected to be close to $400 million. While residents and businesses in the water district wouldn’t see an immediate increase in their bills, it’s unavoidable in the future, and those increases may alarm ratepayers. It’s important to plan improvements in ways that operating costs are also reduced, which lessens the impact on ratepayers.
Activated Sludge Processes Are Commonly Used to Lower Nitrogen
The most common method for nitrogen removal is an activated sludge process. Start with aeration that heightens the habitat for bacteria and protozoa that digest organic matter. Aeration continually happens, which can use up energy costs. You want an efficient aerator that transfers the most oxygen for the lowest operating cost.
The microorganisms take the nitrogen and digest it, which produces waste sludge that contains oxidized organic materials. Some of that organic matter is used to grow more microorganisms, but more of it is moved to settling tanks where the sludge settles to the bottom and is removed. That removed waste ends up in landfills or can be turned into fertilizer in forests or fields that aren’t near bodies of water.
In this process, nitrogen and ammonia are oxidized and phosphorus is removed and nitrites end up as a harmless nitrogen gas. Nitrogen gas can be used to inflate tires, replace oxygen in food packaging to keep foods fresher for longer, and in light bulb manufacturing.
A Magna Rotor Aerator is a solid choice as it is built to withstand heavy use and harsh environments, has stainless steel blades for durability, and available fiberglass covers reduce loss of heat in cold climates. Maintenance is easily handled thanks to the convenient access areas. It’s a high-efficiency, reliable, low-operating-cost option.
Other Options for Nitrogen Removal
Activated sludge processes are the most popular with wastewater districts, but there are other options. Here are some of the other methods being used around the world.
Microalgae have cells that double their biomass every day by feeding on nitrogen. As they do it, they produce bioactive compounds, sugars, proteins, and fats. All of that can be recovered for animal feed and fertilizer. It’s an energy-efficient method, but it’s not effective overall. It’s also expensive to maintain a system that’s capable of removing enough nitrogen.
You can use a solid electron acceptor, such as oxygen and microbes in wastewater to convert nitrogen into electricity. It’s a system being studied as it could be useful for generating clean energy while also taking care of something that’s done every day. But, the hurdles so far have been in creating an efficient system that also is capable of removing the organics.
Anammox (anaerobic ammonium oxidation) is also energy efficient. Bacteria process ammonia and create a nitrogen gas. The only issue is that it processes the wastewater’s ammonia, but it’s not good at handling the organic matter. It’s great for low organic loads, but more than that and the system just doesn’t work well.
Separating Systems Is Also Essential
If your district still has combined sewer lines and stormwater drains, that’s something you should consider changing. Combined Sewer Overflows are still found in more than 750 cities around the U.S. If you have one, your wastewater district must be able to handle flooding rains or high levels of melting snow.
Whether you’re separating your system or upgrading wastewater treatment plant equipment, we have a few suggestions.
Some of the equipment you should consider include Archimedes screw pumps for moving higher volumes of water at faster rates. Grit collection improves your plant’s performance by preventing sand and gravel from building up in tanks and channels and wearing out your pumps. With the grit removed from your plant, aeration is maximized and digester tanks aren’t losing space to sand, gravel, coffee grounds, etc.
Lakeside’s Sequencing Batch Reactor (SBR) is an automated system that processes wastewater treatment in one basin. It mixes, aerates, settles, and removes sludge in one system without foam or scum that’s floating on the surface. Choose SBR or a continuous-feed version known as the CSBR. Benefits include having a smaller system, which is ideal when space is limited. It’s also easy to expand this system.
Older equipment should be replaced before it breaks down. While there is a cost to upgrade, you’ll make more money back by having lower energy costs, less maintenance, and optimal processing of wastewater. Look for equipment with stainless steel components that won’t rust, sealed bearings that require less maintenance, and pumps and mixers that aerate and push wastewater around effectively.
When your residents are saving money in the long run, the cost of upgrading is less alarming. Plus, you don’t want to miss out on current government grants designed to help cities make important upgrades to their sewers and water treatment plants.
Talk to Lakeside Equipment before you face steep fines. Our engineers can go over your current system with you and discuss the most important, cost-effective upgrades to get your plant on the path to meet the changing requirements for things like nitrogen levels, PFAs, and other Clean Water Act limits. You’ll have the insight you need on how to have cleaner water, lower energy bills, and less downtime due to failures.
Sources:
https://pubs.usgs.gov/fs/2000/0135/report.pdf
