What is Nitrogen?
As an element
Nitrogen is one of the primary nutrients critical for the survival of all living organisms. Number 7 in the periodic table, nitrogen is a colorless tasteless odorless element that as a diatomic gas is relatively inert and constitutes 78 percent of the atmosphere It is a necessary component of many biomolecules, including proteins, DNA, and chlorophyll. Although nitrogen is very abundant in the atmosphere as dinitrogen gas (N2), it is largely inaccessible in this form to most organisms, making nitrogen a scarce resource and often limiting primary productivity in many ecosystems. Only when nitrogen is converted from dinitrogen gas (the normal double nitrogen molecule) into ammonia (NH3) does it become available to primary producers, such as plants. Source: Scitable
In Our Water
Nitrites and nitrates are two different molecules that are made up of both nitrogen and oxygen. The chemical difference between nitrites and nitrates is how many oxygen atoms each compound contains. Nitrites have two oxygen atoms and one nitrogen, while nitrates have three oxygen atoms. It is possible for nitrates to turn into nitrites by losing an oxygen atom,and the reverse can happen as well. Nitrates are often found in fertilizers, and both nitrites and nitrates are commonly used in various food preservation processes such as sausage making. Because the isotopes of nitrogen molecules (nitrates and nitrites) can change in the environment, there are no reliable testing methods to determine the sources of nitrogen in water, just that it is there. Why so difficult? Nitrogen is used by plant life along the way. Testing can provide some evidence of transport but whether nitrogen is coming from the fertilizer, septic system, a lightning strike, visits from wildlife, or storm runoff is not easily determined.
How It Is Measured
The EPA and other testing agencies frequently measure nitrates and nitrites as (nitrogen). However, you should be aware that nitrogen, the gas, is not what is being measured but either dissolved nitrates or nitrites. Articles, standards, testing, etc.incorrectly use the terminology interchangeably. Some studies introduce a new term Total Nitrogen (TN). For the purposes of these lessons, the term nitrogen will be defined when known. Otherwise assume it is total nitrogen.
How Nitrogen Gets Into Water
- Through nature
- Lightning Deposition
- Farm animals
- Failures of sewage treatment
- Leakage in piping
- Outflows (excess capacity discharges)
- Injection wells
- Treatment plant failures
- Storm Drains
- Septic systems
Problems with Nitrogen
When nitrogen (in any form) is moved from our environment into our water supplies, excess amounts, it can cause environmental and health issues. Excess nitrogen can cause overstimulation of growth of aquatic plants and algae. Excessive growth of these organisms, in turn, can clog water intakes, use up dissolved oxygen as they decompose, and block light to deeper waters. Too much nitrogen, as nitrate, in drinking water can be harmful to young infants or young livestock. Excessive nitrate can result in restriction of oxygen transport in the bloodstream. Infants under the age of 4 months lack the enzyme necessary to correct this condition (“blue baby syndrome”). Source: US Geological Survey
What are the amounts of nitrogen that are regulated in our water supplies?
In drinking water, the EPA limits the amount of nitrate to 10 mg/ and nitrite to 1 mg/L. Source: EPA
Blue Baby syndrome becomes a risk at 50 mg/l or higher of nitrate. Source: RWL Water Group
The EPA and FDEP Target Regulations on Sewage Treatment Nitrogen requirements are set at 3 MG/L of total nitrogen. Source: Florida Water Resources Journal
Reclaimed water, of which Florida produces 663 million gallons a day, have nitrogen levels averaging 12 to 14 mg/L with amounts varying as high as 50 mg/L depending on seasonality. Here, nitrogen is measured as nitrates. Sources: University of Florida IFAS Extension and Manatee County
Using reclaimed water with its higher rates of nitrogen is good for the environment. The nitrates and nitrites are absorbed by plant life and less fertilizer is needed. Source: University of Florida IFAS Extension
Florida’s Department of Environmental Protection states:
“Other provisions of the Wekiva Parkway and Protection Act call for reuse of reclaimed water in developing local government wastewater master plans and Sections 403.064 and 373.250 Florida Statutes both state that reuse of reclaimed water is a formal state objective.” Source: FDEP
What are the Trends?
The principal issue at hand is the Wekiva Study Area, a section of central Florida containing springs along with the Wekiva River. An FDEP Study documents that during the period of 1988 to 2000, the trend line for nitrogen in spring and river water was dropping. The significance of this time period is that the surrounding area grew in population and numerous homes were being added with many of them utilizing septic systems. It does question why environmentalists and government agencies continue to vigorously pursue the removal of septic systems to help the springs.
How Much Nitrogen Does a Septic System Produce?
As noted in the MACTEC Report, a septic system produces about 17 pounds of nitrogen a year. Other reports show the number to be as high as 22.5 pounds annually. To put this into perspective, the amount of nitrogen from one commercial grade lawn fertilizer is about 3.5 pounds or an amount easily consumed by an average size tree. The point of this comparison is to show that other alternatives to reducing nitrogen exist that are more cost-effective than removing legally permitted, inspected and properly maintained septic systems. The EPA states that “If properly designed, constructed and maintained, your septic system can provide long-term, effective treatment of household wastewater.”.Source: EPA
How Is Nitrogen Removed from Our Water?
To begin with, nitrogen is a necessary element for plant life to exist. Grasses, water plants, trees, even modest amounts of algae will use the nitrogen and,remove it from our water.
Wastewater treatment plants typically include a step for biological nitrogen removal. This means a combination of nitrification and denitrification processes, carried out by various microorganisms. This process requires oxygen which is added by aeration, eventually releasing nitrogen back into the atmosphere. Carbon is also frequently introduced to enhance the nitrogen removal process. Source: Lenntech