Vermifiltration beds with red earthworms treat manure wastewater at Agueda Dairy, cutting CH4 and N2O releases.

Agueda installed wood-chip beds inoculated with Eisenia fetida and native microbes beneath flush lanes. Wastewater percolates through the matrix where worms ingest solids and microbes mineralize organics. The system replaced open lagoons on a 1,200-cow operation and has run continuously since 2024.

Bench-scale trials cited in Environmental Science & Technology 2023 report 68-82 percent methane reduction and 55 percent total nitrogen removal versus anaerobic storage. Agueda’s on-farm sensors logged average CH4 flux of 0.9 g m-2 d-1 versus 4.1 g m-2 d-1 in the prior lagoon. Nitrous oxide fell 40 percent after aeration within the bed increased. Energy demand remained below 0.2 kWh m-3 treated.

Livestock methane accounts for 32 percent of California’s agricultural emissions per CARB 2024 inventory. Vermifiltration addresses both air and water pathways simultaneously, unlike covered digesters that still require separate nutrient treatment. Operational data show bed replacement cycles of 18 months and worm density maintenance above 15 kg m-3, metrics absent from most modeling studies. Next deployments target 50 additional dairies under the state’s Methane Reduction Program by 2027.