disposal because the process is highly efficient, yet requires a

minimum of operation and maintenance.

     The quality of effluent from intermittent sand filters was

documented in Oregon by the Department of Environmental Quality

(Ronayne et al. 1982) .      Biological oxygen demand    (BOD5) and

suspended solid (TSS) were consistently less than 5 mg/l, ammonia

less than 1 mg/l, nitrates between 20 and 40 mg/l and fecal

coliform bacterial averaged a little more than 400 organisms/100


      Sand filtration of septic tank effluent was also studied by

Sauer and Boyle    (1977).   They found that while the unit was

efficient for nitrification of the septic tank effluent, no change

in nitrogen concentration was found to occur.       Only after the

filters remained continuously ponded for over three weeks did

ammonia appear in the effluent. The BOD concentrations for all the

sand filter effluent were less than 10 mg/l. The same conclusion

was reached by Kristiansen (1981a, 1981b) , who reported on the

operation of sand filter trenches. Due to aerobic conditions and

lack of an available energy source, denitrification was not found.

      Because sand filters accomplish excellent BOD5 and suspended

 solids removal, denitrification will not occur without the addition

 of a suitable energy source. Sikoro and Keeney (1974) stated that

 in a septic tank adsorption field, the energy source is the most
 difficult problem in promoting denitrification.

      A nitrogen reducing on-site wastewater disposal system for

 individual homes may be practical      if the organic matter     in