Romero, J. C., (1970). "The movement of bacteria and viruses
through porous media". Groundwater. 8-:37-48.

Ronayne, M. P., Paeth, R. C., and Wilson, S. A.    (1982). Final
Report:  OreQon On-Site Experimental Systems Proaram. State of
Oregon Department of Environmental Quality.

Sandy, A. T. (1987). "Nitrogen removal using a batch
recirculating bottom ash filter", presented at Fifth Nat. Symp.
on Individual and Small Community Sewage Systems, ASAE, Chicago,
Illinois.

Sauer, D. K. and Boyle, W. C.  (1977). "Intermittent sand
filtration and disinfection of small wastewater flows". Proc.
Second Nat. Home Sewage Treatment Symp., ASAE Pub. 05-77, pp.
164-174.

Shammas, N. K.   (1986).  "Interactions of temperature, pH, and
biomass on the nitrification process", J. Water Pollution Control
Fed., 58(1), pp. 52-59.

Sikora, L. J., and Keeney, D. R.  (1974). "Laboratory studies on
simulation of biological denitrification". Proceedings of the
National Home Sewaqe Disposal Symposium. ASAE Pub. PROC-175.
pp. 64-73.

U. S. Environmental Protection Agency, (1980). Design Manual--
Onsite Wastewater Treatment and Disposal Systems. EPA 625/1-80-
012, Cincinnati, Ohio.

U. S. Environmental Protection Agency.  (1978). Management of
Small Wastes Flows.  EPA-600/2-78-173, Cincinnati, Ohio.

U. S. Environmental Protection Agency.  (1975). Process Design
Manual for Nitrogen Control. Office of Technology Transfer of
the U.S. EPA

Viraraghavan, T., (1976).  "Septic Tank Efficiency". ASCS
Journal Environmental Engineering Division, Vol. 102, No. EE2,
pp. 505-508.

Walker, W. G., Bouma, J., Keeney, D. R., and Magdoff, F. R.
  (1973). "Nitrogen Transformations During Subsurface Disposal of
  Septic Tank Effluents in Sands:  I. Soil Transformations". J.
  Environ. Quality, 2(4) , pp. 475-480.

  Walker, W. G., Bouma, J., Keeney, D. R., and O lcott, P. G.
  (1973).  "Nitrogen Transformations During Subsurface Disposal of
  Septic Tank Effluents in Sands:  II. Groundwater Quality".    J.
  Environ. Quality, 2(4), pp. 521-525.

  Warnock, R. G., and Biswas, N.   (1981) . "Study of columnar


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