N03" + 0.833 CH30H + 0.167 H2CO3 ---> 0.5 N2 + 1.33 H20 + HC03

     The above equation shows that bicarbonate is produced and

carbonic acid concentration is reduced whenever nitrate or nitrite

is denitrified to nitrogen gas.      Experiments have shown that

approximately 3.0 mg alkalinity as CaCO3 are produced for every mg

of nitrogen reduced. Thus, the tendency of denitrification is to

at least partially reverse the effects of nitrification and raise

the pH of the wastewater.

      CH3OH (methanol) is shown in the above equation to indicate .the

an adequate carbon source is needed for the denitrifying bacteria

as a source of energy and carbon. In general, 3 mg of methanol for

every mg of N03-N will enable "complete" denitrification       (95%

removal of nitrate) (EPA, 1975).

      Denitrification is also influenced by temperature.    Bremner

and Shaw (1958)    reported denitrification rates increased with

temperature over a 2-250C temperature range. Crites et. al. (1981)

reported the minimum temperature for denitrification       in land

treatment systems is 2-50C.

      pH also affects denitrification rates. Denitrification rates

 are depressed below pH 6.0 and above pH 8.0. The highest rates of

 denitrification occur within the range of pH 7.0 to 7.5 (EPA,

 2.3  Nitrogen Removal Systems for On-Site Waste Disposal Systems

      Intermittent sand filters have been shown to produce effluents

 of very high quality and are presently used throughout the United

 States.  They are well suited to onsite wastewater treatment and