Technology Solutions for Nitrates

Nitrate accumulation is a significant concern to the long-term sustainability of Tulare County.

Nitrate concentrations in many domestic wells in Tulare County exceed safe drinking water standards. Nitrates in drinking water are known to cause reproductive issues such as methemoglobinemia, or “blue baby disease.”

“Nitrate poisoning, called methemoglobinemia (“blue baby” syndrome). Toxic effects occur when bacteria in the infant’s stomach convert nitrate to more toxic nitrite. When nitrite enters the bloodstream, it interferes with the body’s ability to carry oxygen to body tissues. Symptoms include shortness of breath and blueness of the skin around the eyes and mouth. Infants with these symptoms need immediate medical care since the condition can lead to coma and eventually death.”

Source: SWRCB Groundwater Information Sheet: Nitrate. Revised November 2017. Retrieved from SWRCB website: https://www.waterboards.ca.gov/gama/docs/coc_nitrate.pdf.

Photo credit: Tractor spraying fertilizer, iStock 98732175

In response to nitrate concerns, the State Water Board contracted with the University of California, Davis (UC Davis) in 2010 to conduct an independent study on nitrates in the Tulare Lake Basin and the Salinas Valley. The 5-year field study, called Nitrogen Fertilizer Loading to Groundwater in the Central Valley, identified the anthropogenic sources that contribute to nitrate accumulation in groundwater in the Tulare Lake Basin and Salinas Valley.

The study found the following sources of nitrates:

Cropland (96% of total), where nitrogen applied to crops, but not removed by harvest, air emissions, or runoff is leached from the root zone to groundwater. Nitrogen intentionally or incidentally applied to cropland includes:
- Synthetic fertilizer (54%).
- Animal manure (33%).
- Irrigation source water (8%).
- Atmospheric deposition (3%).
- Municipal effluent and biosolids (2%).
Percolation of wastewater treatment plant (WWTP) and food processing (FP) wastes (1.5% of total).
Leachate from septic system drainfields (1% of total).
Urban parks, lawns, golf courses, and leaky sewer systems (less than 1% of total).
Recharge from animal corrals and manure storage lagoons (1% of total).

A Central Valley-wide Salt and Nitrate Management Plan (SNMP) was adopted by the Central Valley Regional Water Quality Control Board (RWQCB) on June 1^st, 2018 and will be implemented over the next four years. The Nitrate Control Program within the SNMP will require all dischargers to evaluate their nitrate contributions and address them either individually or in cooperation with other dischargers in a specialized management zone. The SNMP includes a conditional prohibition in which permittees discharging nitrate will be prohibited from discharging upon receiving a notice to comply unless they are implementing the requirements of the Nitrate Control Program. This will lead to increased effort among all dischargers in the region to adopt new technologies and strategies for managing their nitrate contributions.

Technologies that have a role in SNMP implementation

Technology	Components Managed	Suitable Applications
Algae Production	Nitrogen Phosphorous	High-rate algae ponds require a large footprint, but use little energy, while photobioreactors have a smaller footprint but use more energy. Both are useful for municipal or industrial wastewater treatment, and algae ponds can be used for animal wastewater treatment. Treated water can be used for municipal application, agricultural irrigation, or groundwater recharge in most cases. Produces algae by-product as an additional revenue stream.
Anammox	Nitrogen	Ideal for municipal treatment facilities that lack land to treat nutrients, and want to save energy on nutrient removal. Water needs further treatment before being reused. Produces a little sludge.
Biocatalyst Nitrate Removal	Nitrogen	Useful for direct groundwater remediation or, treating drinking water from wells, or for nitrate removal from wastewater without removing organics. Treated water is potable.
Biochar	Nitrogen Phosphorous Heavy Metals Pesticides Soil Acidity	Biochar is most effective in soils that have been highly degraded due to acidity, heavy metals, compaction, or pesticides. Because restorative agriculture management practices can take many years to rebuild soil carbon, biochar application can be used as a shortcut. Reduces application of synthetic fertilizer.
Cover Crops	Nitrogen Phosphorous	Useful for any crop that doesn’t need surface soil to be cleared annually. Reduces application of synthetic fertilizer.
Forward Osmosis	Nitrogen Phosphorous Heavy Metals Dissolved Solids Salinity Pathogens	Forward osmosis is most effective for industrial users that have two solutions: one that must be concentrated and one that must be diluted. It can be used for just one solution, but requires additional treatment. Food and beverage processors such as fruit juice or dairy processing are examples. Treated water can be used for municipal application, agricultural irrigation, or groundwater recharge Sometimes produces brine, depending on the setup, which is difficult to dispose of.
Membrane Bioreactor	Nitrogen Phosphorous Dissolved Solids Salinity Pathogens	Typically used for large municipal wastewater treatment facilities. Treated water can be used for municipal application, agricultural irrigation, or groundwater recharge.
Nitrification/ Denitrification Basins	Nitrogen	Common for municipal wastewater treatment facilities that need a simple way to meet nutrient discharge TMDLs. Water needs further treatment before being reused. Produces sludge.
No-Till Farming	Nitrogen Phosphorous	Useful for agricultural production that has not yet been mechanized, and that does not require raised rows of soil, such as fresh fruits. Requires 3-7 years to realize many of the benefits. Reduces application of synthetic fertilizer.
Reactive Filtration	Nitrogen Phosphorous Dissolved Solids Salinity Pathogens	Can be used to treat water from agricultural drainage canals, stormwater, or municipal wastewater. Treated water can be used for direct potable reuse, municipal application, agricultural irrigation, or groundwater recharge.
Reverse Osmosis	Nitrogen Phosphorous Heavy Metals Dissolved Solids Salinity Pathogens	Reverse osmosis is most effective for water with high salinity concentrations, or for water that needs to be pure, such as for use within laboratories. Treated water can be used for offsetting water for direct potable reuse, municipal application, agricultural irrigation, or groundwater recharge. Produces brine, which is difficult to dispose of.
Struvite Beads	Phosphorous Nitrogen Magnesium	Struvite replaces traditional fertilizers and lasts for an entire growing season. It is most effective in crops that release organic acid anions from their root systems. Reduces application of synthetic fertilizer.
Struvite Removal	Phosphorous Nitrogen Magnesium	Useful for large municipal facilities with anaerobic digesters and struvite problems. Produces struvite beads which can be sold as an additional revenue stream.
Vermifiltration	Nitrogen Phosphorous	Can be scaled to almost any wastewater application. Great for remote areas and small communities. Industries include dairies, food and beverage processors, and municipal wastewater. Treated water can be used for agricultural irrigation. Produces worm castings, a high-value soil supplement, and vermicompost which can also be applied to agricultural land.

For more information about these technologies, see Report Appendix F: Technology Solutions for Nitrates