The Role of Attachment in the Removal of Faecal Bacteria from Macrophyte and Algal Waste Stabilization Ponds

Attachment of bacteria occurs readily on most available surfaces. The question addressed in this study is whether this mechanism plays a role in pathogen removal in macrophyte and algal waste stabilization ponds. An attempt was made to answer this question in trials on a batch-scale, a bench-scale continuous flow system in Ghana and by using a pilot-scale continuous flow system in Colombia, South America. The results showed that faecal bacteria attach to walls of containers holding wastewater, water lettuce roots and leaves, duckweed fronds and algae. When the die-off rates and mass balance of faecal bacteria on various surfaces in batch-scale incubations were studied, die-off was observed immediately after attachment. Higher die-off was observed in surfaces in the algal ponds. Most of the viable bacteria were found attached to water lettuce roots and to suspended algae. Harvesting of macrophytes removed