The use of evapotranspiration as a means of wastewater disposal

The purpose of this study was to determine the applicability of evapotranspiration as a means of on-site wastewater disposal of septic tank effluent.

The methods of analysis included a laboratory study, mathematical models, and published literature. The laboratory study was to determine the evapotranspiration rates of septic tank effluent and aerobically digested wastewater and to determine the relative fate of some trace metals within the evapotranspiration bed. The mathematical models used were to determine the evapotranspiration rates (outflow) and the infiltration rates (inflow) of the proposed evapotranspiration bed. Literature citations were used to relate soil-groundwater parameters to the inflow-outflow rates and to determine the effective life of the system.

The study has determined that;

1. Evapotranspiration rates of aerobically digested wastewater and septic tank effluent are equal,

2. Evapotranspiration is relatively independent of the dry plant matter produced, and

3. Metal uptake rates were approximately equal for the two feed solutions.

The final results of the study include;

1. A proposed evapotranspiration bed design methodology, and

2. The cost of an evapotranspiration wastewater disposal system was found to be economically justifiably under certain circumstances.