What’s In Your Wastewater: The Impact of Nitrogen & Phosphorus in Ecological Systems

Effective management of wastewater and other environmental risks is crucial for any land development project. While naturally occurring nutrients are present in all streams and lakes, and are essential chemical compounds for sustaining aquatic life, an excess can be detrimental. When nutrient removal is overlooked, treated wastewater discharged into surface waters can cause persistently high nutrient levels. Over time, these elevated levels alter stream ecology, leading to significant negative environmental, social, and economic consequences.

Nitrogen & Phosphorus: Essential but Problematic Nutrients

In surface water ecosystems, the primary nutrients are nitrogen and phosphorus, which occur naturally. Nitrogen gas is abundant in the atmosphere (about 78%), but most aquatic life cannot use it directly; they depend on nitrogen-fixing organisms to convert it into usable forms. Phosphorus naturally exists in rock and sediment and enters the water through erosion. Nature typically provides adequate, but not excessive, amounts of these nutrients.

Aquatic life, including bacteria, algae, and plants, use these nutrients to grow, forming the base of the food chain. Algae, in particular, can reproduce rapidly with ample sunlight and nutrients.

The Danger of Eutrophication

Excess nutrients in water ecosystems lead to a process called eutrophication, where excessive aquatic plant growth depletes the dissolved oxygen in the water. Low dissolved oxygen levels can reduce the diversity and number of beneficial aquatic life forms and promote the growth of less desirable species. This can result in fish kills, harmful algal blooms, and “dead zones.”

The effects of eutrophication range from local to global. Locally, once-popular fishing spots may no longer support game fish, and recreation may decline due to thick, undesirable algae mats. Globally, a large hypoxic (low dissolved oxygen) zone, or “dead zone,” in the Gulf of Mexico, covering approximately 7,000 square miles, has caused an estimated $82 million annual economic loss to the U.S. seafood and tourism industries, according to the National Oceanic and Atmospheric Administration.

Excess nutrients enter water systems through both non-point sources, such as agricultural runoff from fertilizer and livestock manure, and point sources, including wastewater treatment and industrial discharges.

Wastewater’s Role in Nutrient Pollution

The nitrogen and phosphorus found in wastewater primarily originate from human waste, with smaller contributions from food waste, soaps, and detergents. While modern wastewater treatment plants are equipped to remove these nutrients, most older facilities are not. Historically, state and federal regulations did not mandate nutrient removal, so earlier designs didn’t incorporate the necessary processes. Upgrading these plants to remove nutrients is costly, but the environmental, social, and economic costs of nutrient pollution are also high.

Fortunately, technologies are available to reduce nutrients in wastewater discharges, and many states are now moving to regulate nutrient levels in wastewater. At Compass Consulting, we provided engineering and consulting services, commercial and residential land surveying, as well as environmental and regulatory services in Minnesota.

Call us today to discuss the role of wastewater treatment in your development project.