Upflow Filtration of Oxidation Pond Effluent.

摘要

An upflow filtration system employing a sand medium was constructed and operated at the Municipal Oxidation Ponds in Lincoln,Nebraska. The system was operated at loading rates of 0.5to 3.0gal/sq. ft/min (6.25to 37.5gal/min) and backwashed at a rate of approximately 15gal/sq. ft/min (190gal/min). Flow was provided by electrically driven centrifugal pumps. Routine data measurements included COD and suspended solids of influent and effluent and BOD of influent and effluent when the solids concentration in the effluent met current discharge standards. Modifications to the system made during the study included the addition of a steel grid to restrain the filter medium against premature expansion and substitution of a coarser sand (.5mm) for that originally used (.22mm). Conclusions were: (1) the suspended solids and BOD of oxidation pond effluent may be reduced by filtration through a sand medium;and (2) efficiency of removal decreases sharply with increased filtration rate.