Editing Denitrification (section)

==Use in wastewater treatment==
{{Further|Sewage treatment}}
Denitrification is commonly used to remove nitrogen from [[sewage]] and municipal [[wastewater]]. It is also an instrumental process in [[constructed wetland]]s<ref>{{cite journal | last1 = Bachand | first1 = P. A. M. | last2 = Horne | first2 = A. J. | year = 1999 | title = Denitrification in constructed free-water surface wetlands: II. Effects of vegetation and temperature | journal = Ecological Engineering | volume = 14 | issue = 1–2| pages = 17–32 | doi=10.1016/s0925-8574(99)00017-8| bibcode = 1999EcEng..14...17B }}</ref> and [[riparian]] zones<ref>{{cite journal | last1 = Martin | first1 = T. L. | last2 = Kaushik | first2 = N. K. | last3 = Trevors | first3 = J. T. | last4 = Whiteley | first4 = H. R. | year = 1999 | title = Review: Denitrification in temperate climate riparian zones | journal = Water, Air, and Soil Pollution | volume = 111 | pages = 171–186 | doi=10.1023/a:1005015400607| bibcode = 1999WASP..111..171M | s2cid = 96384737 }}</ref> for the prevention of [[groundwater pollution]] with nitrate resulting from excessive agricultural or residential [[fertilizer]] usage.<ref>{{cite journal | last1 = Mulvaney | first1 = R. L. | last2 = Khan | first2 = S. A. | last3 = Mulvaney | first3 = C. S. | s2cid = 18518 | year = 1997 | title = Nitrogen fertilizers promote denitrification | journal = Biology and Fertility of Soils | volume = 24 | issue = 2| pages = 211–220 | doi=10.1007/s003740050233| bibcode = 1997BioFS..24..211M }}</ref>
[[Woodchips#Bioreactor|Wood chip bioreactors]] have been studied since the 2000s and are effective in removing nitrate from agricultural run off<ref>{{cite journal | last1 = Ghane | first1 = E | last2 = Fausey | first2 = NR | last3 = Brown | first3 = LC | date = Jan 2015 | title = Modeling nitrate removal in a denitrification bed | journal = Water Res. | volume = 71C | pages = 294–305 | doi = 10.1016/j.watres.2014.10.039 | pmid = 25638338 | bibcode = 2015WatRe..71..294G }} {{subscription required}}</ref> and even manure.<ref>{{cite journal | last1 = Carney KN | first1 = Rodgers M | last2 = Lawlor | first2 = PG | last3 = Zhan | first3 = X | year = 2013 | title = Treatment of separated piggery anaerobic digestate liquid using woodchip biofilters | journal = Environ Technology | volume = 34 | issue = 5–8| pages = 663–70 | doi = 10.1080/09593330.2012.710408 | pmid = 23837316 | bibcode = 2013EnvTe..34..663C | s2cid = 10397713 }} {{subscription required}}</ref>

Reduction under anoxic conditions can also occur through process called anaerobic ammonium oxidation ([[anammox]]):<ref>{{cite journal | last1 = Dalsgaard | first1 = T. | last2 = Thamdrup | first2 = B. | last3 = Canfield | first3 = D. E. | year = 2005 | title = Anaerobic ammonium oxidation (anammox) in the marine environment | journal = Research in Microbiology | volume = 156 | issue = 4| pages = 457–464 | doi=10.1016/j.resmic.2005.01.011| pmid = 15862442 | doi-access = free }}</ref>

:NH<sub>4</sub><sup>+</sup> + NO<sub>2</sub><sup>−</sup> → N<sub>2</sub> + 2 H<sub>2</sub>O

In some [[Sewage treatment|wastewater treatment plants]], compounds such as [[methanol]], [[ethanol]], [[acetate]], [[glycerin]], or proprietary products are added to the wastewater to provide a carbon and electron source for denitrifying bacteria.<ref>{{cite journal | last1 = Chen | first1 = K.-C. | last2 = Lin | first2 = Y.-F. | year = 1993 | title = The relationship between denitrifying bacteria and methanogenic bacteria in a mixed culture system of acclimated sludges | journal = Water Research | volume = 27 | issue = 12| pages = 1749–1759 | doi=10.1016/0043-1354(93)90113-v| bibcode = 1993WatRe..27.1749C }}</ref> The microbial ecology of such engineered denitrification processes is determined by the nature of the electron donor and the process operating conditions.<ref>{{Cite journal|last1=Baytshtok|first1=Vladimir|last2=Lu|first2=Huijie|last3=Park|first3=Hongkeun|last4=Kim|first4=Sungpyo|last5=Yu|first5=Ran|last6=Chandran|first6=Kartik|date=2009-04-15|title=Impact of varying electron donors on the molecular microbial ecology and biokinetics of methylotrophic denitrifying bacteria|journal=Biotechnology and Bioengineering|volume=102|issue=6|pages=1527–1536|doi=10.1002/bit.22213|pmid=19097144|s2cid=6445650}}</ref><ref>{{Cite journal|last1=Lu|first1=Huijie|last2=Chandran|first2=Kartik|last3=Stensel|first3=David|date=November 2014|title=Microbial ecology of denitrification in biological wastewater treatment|journal=Water Research|volume=64|pages=237–254|doi=10.1016/j.watres.2014.06.042|pmid=25078442|bibcode=2014WatRe..64..237L }}</ref>  Denitrification processes are also used in the treatment of [[industrial wastewater]].<ref>{{cite journal | last1 = Constantin | first1 = H. | last2 = Fick | first2 = M. | year = 1997 | title = Influence of C-sources on the denitrification rate of a high-nitrate concentrated industrial wastewater | journal = Water Research | volume = 31 | issue = 3| pages = 583–589 | doi=10.1016/s0043-1354(96)00268-0| bibcode = 1997WatRe..31..583C }}</ref> Many denitrifying bioreactor types and designs are available commercially for the industrial applications, including [[Electro-biochemical reactor|Electro-Biochemical Reactors (EBRs)]], membrane bioreactors (MBRs), and moving bed bioreactors (MBBRs).

Aerobic denitrification, conducted by aerobic denitrifiers, may offer the potential to eliminate the need for separate tanks and reduce sludge yield. There are less stringent alkalinity requirements because alkalinity generated during denitrification can partly compensate for the alkalinity consumption in nitrification.<ref name=":4" />