Denitrification of agricultural drainage line water via immobilized denitrification sludge

Abstract

Nonpoint source nitrogen is recognized as a significant water pollutant worldwide. One of the major contributors is agricultural drainage line water. A potential method of reducing this nitrogen discharge to water bodies is the use of immobilized denitrifying sludge (IDS). Our objectives were to (1) produce an effective IDS, (2) determine the IDS reaction kinetics in laboratory column bioreactors, and (3) test a field bioreactor for nitrogen removal from agricultural drainage line water. We developed a mixed liquor suspended solid (MLSS) denitrifying sludge using inoculant from an overland flow treatment system. It had a specific denitrification rate of 11.4 mg NO 3 -N g −1 MLSS h −1 . We used polyvinyl alcohol (PVA) to immobilize this sludge and form IDS pellets. When placed in a 3.8-L column bioreactor, the IDS had a maximum removal rate (K MAX ) of 3.64 mg NO 3 -N g −1 pellet d −1 . In a field test with drainage water containing 7.8 mg NO 3 -N L −1 , 50% nitrogen removal was obtained with a 1 hr hydraulic retention time. Expressed as a 1 m 3 cubically-shaped bioreactor, the nitrogen removal rate would be 94 g NO 3 -N m −2 d −1 , which is dramatically higher than treatment wetlands or passive carbonaceous bioreactors. IDS bioreactors offer potential for reducing nitrogen discharge from agricultural drainage lines. More research is needed to develop the bioreactors for agricultural use and to devise effective strategies for their implementation with other emerging technologies for improved water quality on both watershed and basin scales.

Denitrification in Anaerobic Lagoons Used to Treat Swine Wastewater

“…Thus, the method was able to detect very high DEA in swine wastewater, if it existed. The level of DEA has been shown to be a reasonable predictor of nitrogen removal capacity (Hunt et al, 2008), and these tank DEA values were indicative of very high rates of nitrogen removal from the denitrification tanks.…”

A Practice-oriented Review of Woodchip Bioreactors for Subsurface Agricultural Drainage

“…Applied research of drainage bioreactors has recently been facilitated by several NRCS Conservation Innovation Grants (CIGs) in South Dakota, Ohio, and Iowa (South Dakota NRCS, 2011;Ohio NRCS, 2012). Outside the U.S. Midwest, studies in coastal states have used a researchscale bioreactor containing immobilized sludge to treat NO 3 in drainage waters (Hunt et al, 2008).…”

Biosensors: a potential tool for quality assurance and food safety pertaining to biogenic amines/volatile amines formation in aquaculture systems/products

“…These beads could be well preserved by freeze drying and be used in case the nitrifying community collapses in the plant. Polyvinyl alcohol polymer pellets have also been used successfully to immobilize nitrifiers at a fullscale municipal wastewater treatment plant receiving animal waste (Hunt et al 2008). Bioaugmentation was also achieved through the development of nitrifiers within the aerobic microbial granules.…”