Toward an Ecologically Optimized N:P Recovery from Wastewater by Microalgae

Area of Science:

• Environmental Science
• Biotechnology
• Ecology

Background:

• Global phosphorus (P) depletion and surface water enrichment from excessive nutrient use necessitate alternative nutrient sources.
• Wastewater treatment can recover nutrients, but current methods often incompletely recover P.
• Microalgae offer a sustainable solution for assimilating and recovering N, P, and other nutrients from wastewater into valuable products.

Purpose of the Study:

• To investigate the efficacy of Chlorella sorokiniana in removing inorganic nitrogen (N) and phosphorus (P) from concentrated toilet wastewater (black water).
• To analyze the nutrient uptake stoichiometry of algae relative to black water stoichiometry.
• To explore the application of ecological principles for optimizing nutrient recovery from black water.

Main Methods:

• Cultivation of Chlorella sorokiniana in concentrated black water with varying N:P ratios (15–26).
• Monitoring of inorganic N and P removal efficiency.
• Analysis of algal nutrient uptake in relation to wastewater stoichiometry.

Main Results:

• Chlorella sorokiniana successfully removed all inorganic N and P from black water.
• Algal N and P uptake was imbalanced relative to wastewater stoichiometry, with faster P removal than N removal.
• Observed N:P removal imbalances highlight the need for stoichiometric optimization.

Conclusions:

• Chlorella sorokiniana demonstrates potential for comprehensive nutrient removal from black water.
• Ecological stoichiometry and resource-ratio theory can guide strategies for balanced N and P recovery.
• Optimized microalgal cultivation can enhance nutrient recycling and resource recovery from wastewater.