Wastewater nutrient recovery using twin-layer microalgae technology for biofertilizer production

Area of Science:

• Environmental Science
• Biotechnology
• Agronomy

Background:

• Wastewater treatment plants (WWTPs) require efficient tertiary treatment for nutrient removal in sensitive areas.
• Microalgae cultivation offers a sustainable approach for wastewater remediation and resource recovery.

Purpose of the Study:

• To evaluate the feasibility of a twin layer (TL) system for microalgae cultivation in tertiary wastewater treatment.
• To assess the potential of microalgae biomass for bio-based fertilizer production.

Main Methods:

• Cultivation of Scenedesmus sp. in a twin layer (TL) system for nutrient (N and P) removal.
• Analysis of microalgae biomass for nutrient content, enzymatic activity, heavy metals, and pathogens.
• Testing of microalgae-based bio-fertilizer blends on ryegrass and barley.

Main Results:

• The TL system demonstrated high efficiency in removing total soluble nitrogen (up to 66%) and ammoniacal nitrogen (up to 94%).
• Microalgae biomass exhibited rich nutrient content (5.5% N, 8.8% P2O5, 1.5% K2O), high enzymatic activity, and low heavy metal/pathogen levels.
• Bio-based fertilizers with over 2% microalgae inclusion negatively affected ryegrass and barley growth.

Conclusions:

• The twin layer (TL) system is a promising technology for efficient tertiary wastewater treatment.
• Microalgae biomass produced can be a valuable component for high-quality bio-based fertilizers, with careful formulation required.