476
O.D. Brockett and P. Welsby
Fig. l.
accompanying odours were suppressed by agitating the waters with a jet beat to retard
desiccation.
Further problems have arisen towards the end of long, dry, hot summers when
relatively stale, settled sewage from the sedimentation tanks has been fed to the ponds.
Under these conditions the algal population has tended to fall, with bacteria increasing,
causing low dissolved oxygen concentrations and unpleasant odours, and on two
occasions the ponds have needed to be dosed with large quantities of sodium nitrate.
It was felt that most of the difficulties listed above could be related to
oxidation-reduction studies, and a research programme was, therefore, embarked upon to
determine the trends in redox potentials in the pond liquor, at the interface between the
liquor and the bottom sludge, and in the sludge itself.
It should be stressed that for the majority of time the oxidation ponds have
functioned most satisfactorily with green algae and satisfactory dissolved oxygen levels
persisting. As time has progressed the pond conditions have become more stable and free
from problems. Nevertheless, there is need for basic research in the performance of the
oxidation ponds, in order to provide fundamental information concerning oxidation pond
O.D. Brockett and P. Welsby
Fig. l.
accompanying odours were suppressed by agitating the waters with a jet beat to retard
desiccation.
Further problems have arisen towards the end of long, dry, hot summers when
relatively stale, settled sewage from the sedimentation tanks has been fed to the ponds.
Under these conditions the algal population has tended to fall, with bacteria increasing,
causing low dissolved oxygen concentrations and unpleasant odours, and on two
occasions the ponds have needed to be dosed with large quantities of sodium nitrate.
It was felt that most of the difficulties listed above could be related to
oxidation-reduction studies, and a research programme was, therefore, embarked upon to
determine the trends in redox potentials in the pond liquor, at the interface between the
liquor and the bottom sludge, and in the sludge itself.
It should be stressed that for the majority of time the oxidation ponds have
functioned most satisfactorily with green algae and satisfactory dissolved oxygen levels
persisting. As time has progressed the pond conditions have become more stable and free
from problems. Nevertheless, there is need for basic research in the performance of the
oxidation ponds, in order to provide fundamental information concerning oxidation pond