TERTIARY-TREATMENT OF WASTE-WATER WITH PHORMIDIUM-BOHNERI (SCHMIDLE) UNDER VARIOUS LIGHT AND TEMPERATURE CONDITIONS

Experiments were carried out on secondary effluents under different conditions of light and temperature with the aim of evaluating the potential and limits of the epilithic filamentous cyanobacterium Phormidium bohneri (Schmidle) for biotreatment of domestic wastewaters. Aerated cultures were incubated at 10 and 30-degrees-C in a chamber fitted with a photic gradient plate receiving 120 and 720 muE/m2 s. Results indicate that the strain used prefers elevated temperatures, and can withstand considerable variation in light intensity. Response at 30-degrees-C with regard to NH3 and PO4-3 removal agrees with that reported for unicellular chlorophytes. A complete exhaustion of these nutrients was obtained after 3 and 5 days, respectively. It appears that NH3 stripping contributed substantially (38-100%) to the overall NH3 removal efficiency observed in the system. In addition, the protein and carbohydrate content of the biomass produced suggests potential feedstock use.