2018 GSRW_PRB training 9-11-18
Excess nitrate and nitrite in groundwater can be harmful to human health and can lead to eutrophication of coastal waters. In the northeast nitrate from point and nonpoint sources has led to significant water quality decline in Long Island Sound as well as Great Bay in New Hampshire. Septic systems and wastewater ponds can be a significant source of nitrate pollution in groundwater. Excess nitrates from agricultural lands (manure and fertilizer) and residential and commercially developed lands (fertilizer and waste in stormwater) also impact surface water but can also lead to groundwater contamination.
A passive treatment technology, permeable reactive barriers or PRBs, is being used to treat nitrate in many coastal areas and hold promise for use for both small and large-scale settings. PRBs were first used to clean up contaminated groundwater in the late 1980’s. It was originally used to treat dissolved toxic metals and organic chemicals but has more recently been applied to treat excess nutrients in groundwater.
During our training session at the 2018 Granite State Rural Water Association (GSRW) annual conference, we described the application of PRBs to treat nitrate in groundwater in both shallow trench wood chip bioreactors and using injected food grade emulsified vegetable oil. Other nitrate reducing technologies and phosphorus reducing methodology were also reviewed. The talk summarized the results of pilot PRB studies completed in New Hampshire and Massachusetts to address coastal nitrate loading.