RESIDUAL HEAVY-METAL REMOVAL BY AN ALGAE-INTERMITTENT SAND FILTRATION SYSTEM

A laboratory scale study was undertaken to determine the feasibility of using algae growing in wastewater lagoons to absorb residual heavy metals for subsequent complete removal by intermittent sand filtration of the metal laden algae. In semi-continuous cultures the mixed algal flora native to wastewater lagoons absorbed 70-90% of the cadmium and copper from the wastewater media. Chromium absorption was less by ratio (20% was absorbed), but the mass of chromium removed was much greater as high levels of chromium were added. Only one alga (Oscillatoria sp.) which was extremely resistant to chromium grew in the chromium exposed cultures. Nearly total removal of the cadmium and copper was achieved by the algae-intermittent sand filter system. The net chromium removal agreed with the accumulation analyses. The technical feasibility of removing certain heavy metals from wastewater with such a system was established. However, in depth laboratory and field studies must be conducted to maximize system efficiency, demonstrate tactical limitations, and establish design specifications. © 1979.