Biological Denitrification of Groundwater

To promote denitrification, there needs to be an absence of O2, NO3- available as an electron acceptor, and labile carbon (C) to act as an energy source for the denitrifying microbes.

“To promote denitrification, there needs to be an absence of O 2 , NO 3 available as an electron acceptor, and labile carbon (C) to act as an energy source for the denitrifying microbes (Soares, 2000).”

Previous studies have attributed clogging of filters to increased microbial biomass or gas buildup.

“Previous studies have attributed clogging of filters to increased microbial biomass (Soares, 2000) or gas buildup (Soares et al., 1991).”

Many technologies to remove NO3- from groundwater, including anion exchange resins, reverse osmosis, and biological denitrification, are very complex and expensive to maintain.

“Many technologies have been put into place to remove NO 3 -from groundwater, including anion exchange resins, reverse osmosis, and biological denitrification (reviewed in Hiscock et al., 1991 andSoares, 2000), however, these technologies are very complex and expensive to maintain.”

One of the most prevalent problems in using simple C sources is clogging; above ground reactor filters tend to clog if not flushed regularly and in situ systems the aquifer clogs with time.

“One of the most prevalent problems in using simple C sources is clogging; for above ground reactors, the filters tend to clog if they are not flushed regularly and for in situ systems, the aquifer clogs with time (Soares, 2000).”

Methanol addition has been shown to remove 50% of NO3- in aquifers and is the least expensive of all simple C sources, but it is not permitted for use as treatment in potable water supplies in some countries as it can be toxic to humans.

“Addition of methanol has been shown to remove 50% of NO 3 -in aquifers and is the least expensive of all the simple C sources, but it is not permitted for use as treatment in potable water supplies in some countries as it can be toxic to humans (Kruithof et al., 1985;Soares, 2000).”