Scalability and Tunability of Woodchip Bioreactors for Agrochemical Removal and Water Reuse in Commercial Production Settings

High Resolution Image Download MS PowerPoint Slide Frequent irrigation and intensive pesticide use in the specialty crop industry often result in the transport of harmful agrochemicals in return water, threatening production targets and water security. Woodchip bioreactors provide a promising, cost-effective treatment option but are yet to be evaluated for pesticide remediation at commercial scales. Here we describe the season-long (126 days) operation in a commercial greenhouse of a large (1136-L) woodchip bioreactor under a short hydraulic retention time (25 min) supporting pesticide removal and recovery of >90% of valuable nutrients such as nitrate, phosphate, and micronutrients for reuse in irrigation. Shotgun metagenomic sequencing demonstrated the rapid establishment (3–4 weeks) and seasonal stability of a spatially homogeneous community dominated by nitrate-reducing bacteria with numerous pathways for xenobiotic degradation. The presence of pesticide degradation byproducts in the treated water further suggested active bioremediation, but sorption mechanisms are also possible. Together, these results demonstrate the value of woodchip bioreactors as a cost-effective technology for targeted agrochemical removal and sustainable management of irrigation water in commercial horticulture.