| Outdoor biomass productions by indigenous microalgae cultivations with treated effluents are strongly and complexly affected by fluctuated environmental conditions and water qualities in wastewater treatment plants (WWTPs), and mathematical models are required to discuss the production performances. In this study, five-month outdoor cultivations with CO2 addition were conducted in two WWTPs (A and B) to reveal cultivation characteristics and examine applicability of a previously developed model to different WWTPs. The limiting factor for microalgae growth in the treated effluent was different between WWTP A (carbon) and B (phosphorus). Suspended solids (88 mg/L) in the culture at WWTP B was significantly lower than that (113 mg/L) at WWTP A due to the phosphorus starvation in the culture at WWTP B; meanwhile, Chlorophyceae dominated through cultivation periods at the WWTPs. The repeatability of the cultivation characteristics by the model at the same WWTP in different years was verified. It was revealed that the application of the model with some coefficients to a new WWTP was difficult; however, sensitivity analysis of coefficients in the model to identify the dominant one on the biomass productivity and modification of the coefficient based on simple cultivation experiments made the model applicable to the new WWTP. |
