TREATMENT OF DILUTE PIGGERY EFFLUENT WITH VERTICAL FLOW REED BEDS

Washwater from pig pens was led from a lagoon and treated in a series of vertical flow reed beds over 2 yr, A recirculation component was ad ded in the second yr, Five-day biochemical oxygen demand (BOD5), chemi cal oxygen demand (COD), ammonium-N (NH4-N), and nitrate-N (NO3-N) wer e measured during the late winter/early spring periods for the 2 yr, V alues of K-BOD, to describe performance of horizontal flow reed beds, were determined for the vertical flow beds and compared with values de rived from the literature. Maximum BOD, removal was 96%, but averaged 65 and 61% over the first acid second year periods, respectively. Perf ormance of each stage, as indicated by percent removal of BOD5, was be st described by an inverse logarithmic function of hydraulic load. Pen ding was a problem, indicating a need for control of organic loading, Efficient nitrification was not achieved so that the treatment did not result in waste suitable for direct discharge to surface water.