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.