an apparatus and method for treating and reusing the wastewater discharged from agricultural animal farms . the apparatus and method of the present invention is designed to be a zero discharge system in which no wastewater will be discharged or spray irrigated . the wastewater effluent is first passed through a mechanical screen were bulk solids are separated and partially de - watered . the screened effluent is then directed to a primary plastic - lined earthen lagoon where it undergoes aerobic digestion utilizing specially selected bacteria . after treatment in the primary lagoon , the wastewater effluent is used to wash the floors of the hog houses or undergoes a purification phase including solids separation / denitrification , filtration and sterilization . the solids separation / denitrification phase preferably takes place in an anoxic environment in preferably above - ground tanks where suspended solids removal will occur as well as denitrification for nitrate reduction . the clarification process may be facilitated through use of polymer addition . the majority of solids will be sent to a plurality of drying beds for de - watering and subsequent removal .