NUTRIENT REMOVAL BY THERMOPHILIC FISCHERELLA (MASTIGOCLADUS-LAMINOSUS) IN A SIMULATED ALGACULTURE PROCESS

A novel nutrient removal/waste heat utilization process was simulated using semicontinuous cultures of the thermophilic cyanobacterium Fisch erella. Dissolved inorganic carbon (DIC)-enriched cultures, maintained with 10 mg l(-1) daily productivity, diurnally varying temperature (f rom 55 degrees C to 26-28 degrees C), a 12:12 light cycle (200 mu E se c(-1) m(-2) and 50% biomass recycling into heated effluent at the begi nning of each light period, removed > 95% of NO3- + NO2--N, 71% of NH3 -N, 82% of PO43- -P, and 70% of total P from effluent water samples co ntaining approximately 400 mu g l(-1) combined N and 60 mu g l(-1) P. Nutrient removal was not severely impaired by an altered temperature g radient, doubled light intensity, or DIC limitation. Recycling 75% of the biomass at the end of each light period resulted in unimpaired NO3 - + NO2- removal, 38-45% P removal and no net NH3 removal. Diurnally v arying P removal, averaging 50-60%, and nearly constant > 80% N remova l are therefore projected for a full-scale process with continuous bio mass recycling.