wastewater could be used as the carbon source for denitrification.

Laak et al. (1981) and Laak       (1981) reported on a different

modification of a conventional septic tank system. Laak developed

the RUCK system in which the organic matter in greywater (kitchen

and  laundry   wastewater)  is used   as  the  carbon   source  for

denitrification of nitrified blackwater (bathroom wastewater).

They concluded that organic carbon in the greywater was as

efficient as methanol in supporting denitrification and that an

overall nitrogen removal level of 70% could be achieved using the

passive RUCK system.

      Warnock and Biswas (1981) used effluent from a kitchen garbage

 grinder as an energy source for denitrification in columns. A C:N

 ratio of 4:1 was found to be optimal to produce satisfactory


      One of the most recent on-site wastewater disposal system with

 nitrogen reducing potential is a recirculation sand filter, which

 utilizes the organic matter in septic tank effluent as the carbon

 source for denitrification.

      The recirculating sand filter is a simple, compact method of

 providing improved treatment of wastewater with a low level of

 maintenance.     Recirculating   sand  filters  provide  secondary

 treatment beyond a septic tank prior to surface or subsurface
 disposal (Loudon et. al., 19 )
      A typical recirculating sand filter consists of a septic tank,

 a free access sand filter, and a recirculation tank as shown in

 figure 2.1.   The recirculation tank is typically 1/4 to 1/2 the