Many municipalities are facing new effluent limits on lagoon ammonia, based on revised EPA guidelines. What is ammonia, and why is the EPA so concerned about it?
In this article, we’ll discuss lagoon ammonia specifically, then outline the wider implications of ammonia in the environment, namely its threat to human and animal health and how it damages waterways.
What Is Wastewater Lagoon Ammonia?
Lagoon ammonia is a form of nitrogen that enters a wastewater lagoon as a result of human urea and other sources. Ammonia-Nitrogen is part of Organic Nitrogen, and exists in ionized NH4 and unionized NH3 forms, depending on the water’s pH. NH3 is the form targeted by new effluent permits, as it is toxic to fish, promotes algae, and harmful to all aquatic life. In a wastewater lagoon, the majority of total Nitrogen in a lagoon is in the form of Ammonia. The sum of Organic Nitrogen and Ammonia-Nitrogen together is expressed as Total Kjeldahl Nitrogen (TKN).
In a previous article, Sources and Treatment of Lagoon Ammonia, we discussed the origin of lagoon ammonia specifically, although environmental ammonia has many sources. In fact, the primary cause of excess nutrients in waterways is fertilizer runoff. Despite not being the leading source of environmental ammonia, wastewater lagoon ammonia is still a significant factor. If one considers there are roughly 6,000 lagoons in the United States with an average flow of 300,000 gallons per day and effluent ammonia concentration of 30 mg/L, then that amounts to approximately 450,000 lbs of ammonia discharged into the environment per day from wastewater lagoons nationwide!
Whatever its source, ammonia can cause tremendous damage to our ecosystem. Following are 3 reasons the EPA is cracking down on ammonia from all sources:
3 Reasons the EPA is Regulating Lagoon Ammonia Effluents
1. It causes eutrophication, the explosive overgrowth of plant life—especially simple plants like algae and aquatic weeds—as it responds to the nutrient loads of nitrogen and phosphorus. As these plants proliferate, they choke out other life forms, causing stagnancy, scummy algae blooms, and sediment. Water becomes cloudy and possibly odorous. Toxic algae may proliferate and contaminate the water supply, or the toxins can work their way up the food chain as they are consumed by shellfish. When the plants die, they sink to the bottom of the water and decompose. The decomposition process further depletes the oxygen that fish and other organisms need to survive, causing hypoxia.
2. It causes hypoxia: low oxygen conditions, where the concentration of dissolved oxygen in the water is below 2mg/L—too low to sustain life. The second largest hypoxic area, or “Dead Zone,” in the world is where the Mississippi River enters the Gulf of Mexico. The size of the Gulf Dead Zone varies each year: This summer, it measured just over 5,000 square miles. When hypoxic conditions occur, aquatic animals leave; those that cannot escape, like mussels and crabs, die. Hypoxia also makes it difficult for young fish and shellfish to find the food they need to reach adulthood, reducing reproduction. Dead zones are a threat to commercial and recreational fishing and the local economies that depend on them.
3. It’s toxic to aquatic animal life. In addition to causing eutrophication and hypoxia, ammonia itself is toxic. Freshwater mussels are very sensitive to unionized ammonia (NH3) and are the largest group of endangered animals in North America, according to the U.S. Geological Survey. In addition to their value as a food source for many animals, mussels also act as little filters, clearing contaminants and sediment from the water. Because of their sensitivity to pollutants, the mussels’ declining populations serve as an alarm to scientists—the “canary in the coal mine”—that an ecosystem is in jeopardy. Higher up the food chain, fish like trout, bluegill, catfish, perch, and salmon also appear on the EPA’s acute toxicity dataset for ammonia sensitivity. A reduction in fish population damages the commercial fishing industry, reduces the availability of food fish for humans and animals, and takes the fun out of recreational fishing.
What it means to you
Clearly, the EPA has good reasons to try to minimize the amount of ammonia released into the environment. As states adapt permits to meet the EPA’s guidelines, lagoon operators are challenged to reduce ammonia levels in effluent—something lagoons were not originally designed to do. Municipalities may fear significant capital expense and increased maintenance and operations costs, at a time when budgets are already tight, in order to meet the new requirements. However, it is possible to achieve near-complete ammonia removal—even in cold weather—with an existing lagoon system.
NitrOx Lagoon Ammonia Removal
Lagoon ammonia removal via nitrification can be achieved without scrapping your current treatment system. The NitrOx™ Reactor was designed to be incorporated into an existing system for the sole purpose of ammonia removal, helping to keep capital costs low—at 2/3 the cost of existing nitrification options—and minimize the financial burden of plant upgrades. The NitrOx system, through controlled thermal regulation, biomass, mixing, and aeration, optimizes conditions for nitrification, even in cold weather.
Download our Lagoon Ammonia Removal Whitepaper for a more in-depth look into the alternative solutions to ammonia removal.
Preserving the environment is everyone’s responsibility, but especially for those of us entrusted with wastewater treatment. See us at WEFTEC in Chicago, September 28–30, 2015, Booth #770, to learn more about NitrOx and our other lagoon technologies.