Most of the nutrients that fuel the Gulf of Mexico dead zone come from Midwestern farms, and enter the gulf via the Mississippi River watershed.
Treating farm runoff before it enters watersheds can reduce nutrients that promote overgrowth of algae
In 2017, the dead zone in the Gulf of Mexico broke a record, exceeding an average of 5,380 square miles to reach 8,776 square miles, roughly the size of New Jersey. Dead zones occur when seawater becomes overloaded with nutrients from agricultural runoff and other sources. The nutrients lead to an overgrowth of algae that deplete the oxygen in the water, killing off aquatic life.
While one might look to the Gulf Coast states for the source of the nutrient overload, the nitrogen and phosphorus that feed the dead zone off the southern coast of the United States largely originate in Midwestern states as agricultural runoff that enters the Mississippi River watershed. While regulation of runoff has been minimal so far, many farmers anticipate more stringent rules.
What’s being done on a statewide level? Illinois, which is the largest contributor of phosphorus to the Gulf of Mexico, has set ambitious nutrient reduction goals, but so far has missed them. The problem is getting even worse, suggesting that a federal task force assigned to shrink the dead zone by 1,000 square miles has been ineffective. While wastewater treatment plants have shrunk their nutrient discharges to comply with permit limits, nutrients in agricultural runoff dwarf wastewater treatment plant contributions and the relatively tiny contribution of urban stormwater.
Lack of Regulation
Efforts to reduce agricultural nutrient contributions are also largely voluntary because nonpoint sources of pollution remain unregulated at the federal level and generally at the state level as well. Nonetheless, Illinois set an ambitious target of 15% nitrogen and nitrate reductions and 25% phosphorus reductions by 2025, but since the goals were set, nitrogen levels have increased by 13% and phosphorus levels have increased by 35%.
With voluntary efforts failing, many farmers fear it won’t be long before regulation reaches their operations. A recent University of Missouri-Columbia paper by a group of experts in various fields gave voice to the increasing desire for regulation of farm runoff. It recommended that the Clean Water Act be amended to require states to regulate their own nonpoint-source pollution, and set aside funding to support efforts and education campaigns.
One Illinois soybean farmer near Springfield expressed the general trepidation in the sector: “… somebody’s going to tell you what to do,” but, “It’s easier to do it the right way without regulation than it is to be regulated.”
Reducing Nonpoint-Source Nutrient Pollution
What can be done to reduce runoff pollution at the farm level? Commonly used methods include:
- Buffer strips
- Planting cover crops
- Gentler tilling practices
- Improved fertilizer application techniques
Many farmers already use drainage water management (DWM) to control runoff and the water table under their fields. DWM is done with tile drainage, which uses a system of underground drainage pipes. When contaminated runoff is removed via a pipe or ditch, it becomes a point source that can be treated with established treatment processes.
There are proven wastewater treatment options that are especially well-adapted for rural applications. They include containerized Aspiral™ wastewater treatment units, which use membrane aerated biofilm reactor (MABR) technology to deliver exceptionally high nutrient removal rates with a very low energy requirement. Aspiral™ effluent meets the toughest agricultural water reuse standards in the world, including California’s Title 22 and China’s Class 1A.
If you choose to use anaerobic digestion to treat your farm’s wastewater, Fluence’s Nitro can treat the sidestream to remove more than 90% TIN, eliminating up to 20% of total nitrogen load to the plant.
Contact the experts at Fluence to learn how your farming region can prepare for approaching regulation with the most efficient and rural-ready modular units on the market.
