Nutrient Removal in Advanced Septic Systems

Nutrient Removal in Advanced Septic Systems: How It Works and Why It’s Important

Introduction

Traditional septic systems are effective at treating basic household wastewater, but they often fall short when it comes to removing excess nutrients like nitrogen and phosphorus. These nutrients, when they reach water bodies, can cause harmful algal blooms, oxygen depletion, and other environmental issues. To address these challenges, advanced septic systems with nutrient removal capabilities are becoming more common, particularly in sensitive areas like Florida, where protecting water quality is crucial.

In this post, we’ll explain how advanced septic systems remove nutrients, why nutrient removal is important, and how these systems differ from conventional septic setups.


Why Is Nutrient Removal Important?

Nitrogen and phosphorus are essential nutrients for plant growth, but when they are released in excess into water bodies, they can lead to nutrient pollution.

This pollution triggers harmful algal blooms, like red tide or blue-green algae, which deplete oxygen levels in water and harm marine life.

In Florida, where sandy soils and high water tables are common, untreated nutrients from septic systems can easily leach into groundwater and nearby water bodies, contributing to pollution.

By removing these nutrients before wastewater enters the environment, advanced septic systems help protect ecosystems, maintain water quality, and reduce the risk of public health issues associated with contaminated water.


How Advanced Septic Systems Remove Nutrients

Advanced septic systems are designed to go beyond the basic treatment provided by traditional systems.

While conventional septic systems focus on separating solids and allowing liquid waste (effluent) to filter through a drain field, advanced systems incorporate additional processes to specifically target and reduce nutrient levels—especially nitrogen.

These systems are often referred to as nitrogen-reducing or nutrient-removal systems.

Here’s how nutrient removal typically works in advanced septic systems:

1. Biological Nitrogen Removal (BNR)

One of the most effective methods for removing nitrogen from wastewater is biological nitrogen removal (BNR), which involves using natural bacteria to convert harmful forms of nitrogen into harmless nitrogen gas, which is then released into the atmosphere.

The BNR process occurs in two main steps:

  • Nitrification: In this phase, bacteria in the septic tank or treatment unit convert ammonia (NH3) and organic nitrogen from wastewater into nitrate (NO3-). This process requires oxygen, so the system often incorporates an aerobic chamber where oxygen is added to support the bacteria.
  • Denitrification: Once nitrification occurs, the next step is to remove nitrate. This is done in an anaerobic chamber (a chamber without oxygen), where another type of bacteria converts nitrate into nitrogen gas (N2). The nitrogen gas is harmless and naturally returns to the atmosphere.

2. Phosphorus Removal

While nitrogen is the primary nutrient targeted in most advanced systems, phosphorus can also be removed through chemical and physical processes.

Phosphorus removal typically involves binding the phosphorus in wastewater to solid particles, which can then be filtered out.

  • Chemical Precipitation: Chemicals such as alum or iron salts are added to the wastewater to bind with phosphorus, forming solid particles (precipitates). These particles are then removed through filtration or settling processes in the tank.
  • Physical Filtration: In some systems, sand filters or media filters are used to physically remove phosphorus from the wastewater before it reaches the drain field.

3. Additional Treatment Units

In some advanced septic systems, extra treatment units are used to further clean the wastewater. These include:

  • Aerobic Treatment Units (ATUs): These units pump oxygen into the wastewater, promoting the growth of aerobic bacteria that help break down organic matter and reduce nitrogen levels.
  • Recirculating Sand Filters (RSFs): Wastewater is passed through layers of sand or gravel, which helps filter out nutrients and pathogens. This additional filtration improves water quality before it reaches the drain field.
  • Constructed Wetlands: Some advanced systems incorporate constructed wetlands, where natural processes involving wetland plants, soil, and microorganisms help to break down nutrients and filter out contaminants.

4. Effluent Monitoring

Advanced septic systems often come with monitoring devices to track the quality of effluent being released into the environment.

These devices ensure that nutrient levels stay within safe limits and help homeowners and regulators detect any issues with the system early on.


Benefits of Nutrient Removal in Advanced Septic Systems

1. Protecting Water Quality

By removing nitrogen and phosphorus from wastewater, advanced septic systems help protect groundwater and surface water quality. This is especially important in areas near lakes, rivers, estuaries, and coastal waters, where nutrient pollution can have devastating effects.

2. Reducing Algal Blooms

Nutrient removal reduces the likelihood of harmful algal blooms, which are triggered by excess nitrogen and phosphorus in water bodies. These blooms deplete oxygen, kill fish, and damage ecosystems. In Florida, where harmful algal blooms like red tide are a major concern, reducing nutrient runoff is critical.

3. Safeguarding Public Health

Advanced nutrient-removal systems help prevent contaminants from entering drinking water supplies. In areas where residents rely on private wells, removing nitrogen from septic effluent can reduce the risk of nitrate contamination, which can cause health issues like blue baby syndrome.

4. Complying with Environmental Regulations

As nutrient pollution becomes a growing concern, many local and state governments are requiring homeowners in sensitive areas to upgrade to nutrient-removal septic systems.

Advanced systems help homeowners stay compliant with regulations aimed at protecting water quality.


Where Are Advanced Septic Systems Needed?

Advanced septic systems are particularly beneficial in areas where the risk of nutrient pollution is high. These include:

  • Coastal Regions: Areas near the coast are more vulnerable to nutrient pollution due to their proximity to sensitive marine ecosystems and the risk of leaching into groundwater.
  • Areas with High Water Tables: In regions with high water tables, there is less distance between the septic drain field and groundwater, making it easier for nutrients to reach water supplies.
  • Near Lakes and Rivers: Homes located near lakes, rivers, or other freshwater bodies may be required to use advanced systems to reduce nutrient runoff into these ecosystems.

Conclusion

Advanced septic systems with nutrient removal capabilities are a vital tool in protecting Florida’s water bodies and groundwater from nutrient pollution.

These systems use biological, chemical, and physical processes to reduce nitrogen and phosphorus in wastewater, preventing harmful contaminants from reaching sensitive environments.

By investing in advanced treatment technologies, homeowners can play a critical role in preserving water quality and protecting public health.

If you’re interested in upgrading to an advanced septic system or learning more about nutrient removal, contact us today for expert advice and guidance.


 

Nutrient Removal in Advanced Septic Systems

Nutrient Removal Method How It Works
Nitrogen Biological Nitrogen Removal (BNR) – Nitrification: Converts ammonia to nitrate using aerobic bacteria.
– Denitrification: Converts nitrate to harmless nitrogen gas in anaerobic conditions.
Phosphorus Chemical Precipitation & Physical Filtration – Chemicals like alum bind phosphorus into solid particles, which are then filtered out or removed.
Additional Units Aerobic Treatment Units (ATUs), Sand Filters – ATUs add oxygen to support bacteria in breaking down nutrients.
– Sand filters physically remove nutrients.
Effluent Monitoring Monitoring Devices – Tracks nutrient levels in effluent to ensure they stay within safe limits.

 

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