Temperature also plays an important role in the nitrification

process. The optimum temperature range for nitrification has been
reported as is to 350C with nitrification ceasing at 50C and below
(Shatemas, 1986). Lamb et. al. (1989) reported nitrification rates

as low as 25% at temperatures lower than h0aC     a number of other
studies also suggests that below 150C, temperature has a significant

impact on nitrification rates.
      The biological    process  of  denitrification   involves  the

  conversion of nitrate nitrogen to a gaseous nitrogen species. The
  gaseous product is primarily nitrogen gas but also may be nitrous
  oxide or nitric oxide.   Denitrification can be accomplished by a

  relatively broad range of facultative heterotrophic bacteria
  including psuedomonas, 14icrococcus, Archromobacter and Bacillus
  (EPA, 1975).
        Because denitrifying bacteria are facultative anaerobes, a
   sufficiently high concentration of dissolved oxygen can prevent the

   use of N03 as the terminal electron acceptor.    In general, cells

   exposed to more than 0.1 to 0.2 mg/l of 02 do not denitrifY (Rittman

   and Langeland, 1985).                                hc    h   is
         Denitrification is also a two-step process in which the first

    step is a conversion of nitrate to nitrite.       The second step
    converts the nitrite to nitrogen gas:
    N03- + 0.33 CH3OH ---> NOI + 0.33 H20 + 0.33 Hi2C03
    NOJ- + 0.5 CH3OHI + 0.5 H2C03 ----> 0.5 N2 + flC03 + H20
          The overall denitrification reaction can be written as (EPA,