Advanced wastewater treatment with microalgae-indigenous bacterial interactions

Area of Science:

• Environmental Microbiology
• Biotechnology
• Wastewater Engineering

Background:

• Microalgal-indigenous bacterial wastewater treatment (MBWT) shows promise for nitrogen and phosphorus removal.
• Current batch systems limit MBWT application, and biological mechanisms require further understanding.

Purpose of the Study:

• To investigate the viability and microbial dynamics of a continuous flow microalgae-indigenous bacteria advanced wastewater treatment system (CFMBAWTS).
• To assess the impact of varying hydraulic retention times (HRTs) on CFMBAWTS performance using secondary effluent.
• To elucidate the synergistic interactions and underlying biological mechanisms between microalgae and indigenous bacteria.

Main Methods:

• Operated a continuous flow system with secondary effluent.
• Varied hydraulic retention times (HRTs) to evaluate system performance.
• Analyzed microbial dynamics, nutrient removal, CO2 fixation, energy yield, and biomass composition.

Main Results:

• A stable, mutually beneficial relationship between microalgae and indigenous bacteria was established.
• CFMBAWTS achieved compliance with stringent wastewater discharge standards across various HRTs (6-15 h).
• Optimal conditions at 15 h HRT yielded high CO2 fixation (1.23 g L⁻¹), energy yield (32.35 kJ L⁻¹), and lipid (33.91%) and carbohydrate (41.91%) content.

Conclusions:

• Continuous flow MBWT is a feasible and effective technology for advanced wastewater treatment.
• The symbiotic relationship enhances microbial growth, nutrient removal, and resource recovery.
• This study provides a foundation for optimizing CFMBAWTS for practical wastewater treatment applications.