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AlgaeSim, a dynamic multiple-systems (C, N, P) mass balance model, was developed to explore the potential for algae biomass production from wastewater by coupling two photobioreactors into the main treatment train at a municipal wastewater resource recovery facility (WRRF) in Tampa, Florida. The scoping model examined the synergy between algae cultivation and wastewater treatment through algal growth and substrate removal kinetics, as well as through macroeconomic analyses of biomass conversion to bioproducts. Sensitivity analyses showed that biomass production is strongly dependent on Monod variables and harvesting regime, with sensitivity changing with growth phase. Profitability was sensitive to processing costs and market prices of products. Under scenarios based on current market conditions and typical algae production, AlgaeSim shows that a WRRF can potentially generate significant profit if algae are processed for biodiesel, biogas, or fertilizer. Wastewater resource recovery facilities could similarly save on operating costs resulting from the reduction in aeration (for nitrification) and chemicals (for denitrification).

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Two monocultures (Chlorella sorokiniana and Botryoccocus braunii) and two native polycultures derived from the clarifiers (following a pure oxygen BOD reactor and a nitrification reactor) at a municipal wastewater treatment plant were cultivated in synthetic media and clarified effluent from two stages of the wastewater treatment plant. Water quality and algae biomass composition were measured at the beginning and end of 12 day batch tests to compare nutrient removal, assimilation, and growth potential. Soluble COD increased significantly (p<0.05) in with algae monocultures and one polyculture grown in clarified effluent. Total nitrogen decreased significantly (p<0.05) in all wastewater batches, and phosphate removal was also significant (p<0.05) in most cases. After cultivation in most growth media, the two monocultures and one polyculture appeared to accumulate phosphorous. The post-BOD clarified effluent supported the highest yield for all species studied, and the algae community native to the post-BOD clarifier achieved the highest yield of all species studied.

Algal monocultures (Chlorella sorokiniana and Botryococcus braunii) and algal communities native to clarifiers of a wastewater treatment plant were batch cultivated in (1) clarified effluent following a biochemical oxygen demand (BOD) removal reactor post-BOD removal clarified effluent (PBCE), (2) clarified effluent following a nitrification reactor post-nitrification clarified effluent (PNCE), and (3) a reference media (RM). After 12 days, all algal species achieved nitrogen removal between 68 and 82% in PBCE and 37 and 99% in PNCE, and phosphorus removal between 91 and 100% in PBCE and 60 and 100% in PNCE. The pH of the wastewater samples increased above 9.8 after cultivation of each species, which likely aided ammonia volatilization and phosphorus adsorption. Both monocultures grew readily with wastewater as a feedstock, but B. braunii experienced significant crowding from endemic fauna. In most cases, native algal species' nutrient removal efficiency was competitive with augmented algal monocultures, and in some cases achieved a higher biomass yield, demonstrating the potential to utilize native species for nutrient polishing and algal biomass production.