Granular activated algae for wastewater treatment.

Area of Science:

• Environmental Science
• Biotechnology
• Water Treatment Engineering

Background:

• Low-strength wastewater treatment presents challenges for conventional methods.
• Microalgae-based systems offer a sustainable approach to wastewater management.
• Granular activated algae systems combine biological treatment with efficient biomass harvesting.

Purpose of the Study:

• To evaluate the efficacy of activated algae granules for low-strength wastewater treatment.
• To assess the removal rates of key pollutants including chemical oxygen demand (COD), ammonia (NH4+), and phosphates (PO43-).
• To investigate the potential for microalgae harvesting and system sustainability.

Main Methods:

• Sequential batch reactor operation with activated algae granules.
• Controlled light intensity (235 μmol/m²/s) and aerobic conditions.
• Monitoring of pollutant concentrations, removal rates, and microalgae settling velocity.

Main Results:

• High removal efficiencies for COD (86-98%) and significant NH4+ removal (1.8 ± 0.6 mg/g h).
• Successful nitrification processes observed, with NH4+ to NO3- transformation rates increasing to 1.5 ± 0.4 mg NH4+/g h.
• Wide range of PO43- removal (11-85%) and efficient microalgae recovery (99.85-99.99%) with a settling velocity of 19 ± 3.6 m/h.

Conclusions:

• Activated algae granules are a promising technology for efficient low-strength wastewater treatment.
• The system demonstrates effective removal of COD, NH4+, and PO43-, alongside robust nitrification and potential for denitrification.
• Cost-efficient microalgae harvesting is achievable, enhancing the overall sustainability of the process.