Zooplankton-based reactors for tertiary wastewater treatment: A pilot-scale case study

Area of Science:

• Environmental Engineering
• Ecology
• Wastewater Treatment Technologies

Background:

• Nature-based wastewater treatments offer sustainable, cost-effective solutions for rural areas.
• Improving the efficiency of these systems is crucial for wider adoption.
• Zooplankton-based reactors represent an innovative approach to on-site wastewater management.

Purpose of the Study:

• To evaluate the efficiency of a zooplankton-based reactor for secondary urban wastewater treatment.
• To assess the technological cooperation between zooplankton and biofilms.
• To determine the effluent water quality for reuse applications.

Main Methods:

• A 1.5 m³ zooplankton-based reactor utilizing Daphnia magna and biofilms was operated for 14 months.
• Evaluated nutrient polishing (organic matter, nitrogen) and solids removal (TSS, turbidity).
• Assessed performance under varying conditions, including flow rates and seasonality.

Main Results:

• The reactor demonstrated low seasonality effects on nutrient and solids removal.
• Optimal performance, including reduced organic carbon, nitrogen, E. coli, and solids, occurred in winter at 750 L/d.
• Effluent quality met Spanish legislation standards for reuse in six applications.

Conclusions:

• The zooplankton-based reactor is a viable eco-sustainable tertiary treatment for water reuse.
• The system shows potential for on-site wastewater management.
• Reactor robustness against temperature and oxygen fluctuations requires further improvement for year-round efficiency.