Editing Denitrification (section)

==Non-biological denitrification==

A variety of non-biological methods can remove nitrate. These include methods that can destroy nitrogen compounds, such as chemical and electrochemical methods, and those that selectively transfer nitrate to a concentrated waste stream, such as ion exchange or reverse osmosis. Chemical removal of nitrate can occur through advanced oxidation processes, although it may produce hazardous byproducts.<ref name="Rayaroth Aravindakumar Shah Boczkaj 2022 p=133002">{{cite journal | last1=Rayaroth | first1=Manoj P. | last2=Aravindakumar | first2=Charuvila T. | last3=Shah | first3=Noor S. | last4=Boczkaj | first4=Grzegorz | title=Advanced oxidation processes (AOPs) based wastewater treatment - unexpected nitration side reactions - a serious environmental issue: A review | journal=Chemical Engineering Journal | publisher=Elsevier BV | volume=430 | year=2022 | issn=1385-8947 | doi=10.1016/j.cej.2021.133002 | page=133002| doi-access=free | bibcode=2022ChEnJ.43033002R }}</ref> Electrochemical methods can remove nitrate by via a voltage applied across electrodes, with degradation usually occurring at the cathode. Effective cathode materials include transition metals, post transition metals,<ref name="NitrateElectroReview">{{cite journal | last1=Rajmohan | first1=K. S. | last2=Gopinath | first2=M. | last3=Chetty | first3=Raghuram | title=Review on challenges and opportunities in the removal of nitrate from wastewater using electrochemical method | publisher=Triveni Enterprises | volume=37 | year=2016 | issn=2394-0379 | pages=1519–1528}}</ref> and semi-conductors like TiO<sub>2</sub>.<ref name="Ji Niu Xu Wang 2021 p=129706">{{cite journal | last1=Ji | first1=Yangyuan | last2=Niu | first2=Junfeng | last3=Xu | first3=Dong | last4=Wang | first4=Kaixuan | last5=Brejcha | first5=Jacob | last6=Jeon | first6=Seunghyo | last7=Warsinger | first7=David M | title=Efficient electrocatalysis for denitrification by using TiO<sub>2</sub> nanotube arrays cathode and adding chloride ions | journal=Chemosphere | publisher=Elsevier BV | volume=274 | year=2021 | issn=0045-6535 | doi=10.1016/j.chemosphere.2021.129706 | page=129706| pmid=33540319 | bibcode=2021Chmsp.27429706J | s2cid=231818217 | url=https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1047&context=mepubs | url-access=subscription }}</ref> Electrochemical methods can often avoid requiring costly chemical additives, but their effectiveness can be constrained by the pH and ions present. Reverse osmosis is highly effective in removing small charged solutes like nitrate, but it may also remove desirable nutrients, create large volumes of wastewater, and require increased pumping pressures. Ion exchange can selectively remove nitrate from water without large waste streams,<ref name="Krueger 1949 pp. 482–487">{{cite journal | last=Krueger | first=Gordon M. | title=A method for the removal of nitrates from waterprior to use in infant formula | journal=The Journal of Pediatrics | publisher=Elsevier BV | volume=35 | issue=4 | year=1949 | issn=0022-3476 | doi=10.1016/s0022-3476(49)80063-1 | pages=482–487| pmid=18143940 }}</ref> but do require regeneration and may face challenges with absorption of undesired ions.