Biodegradation of a mixture of the herbicides ametryn, and 2,4-dichlorophenoxyacetic acid (2,4-D) in a compartmentalized biofilm reactor

In this work, an efficient degradation process for the removal of 2,4-D and ametryn, together with organic and inorganic adjuvants used in the commercial formulations of both herbicides, was developed. Although both compounds are toxic for microbial communities, ametryn is markedly more toxic than 2,4-D. In spite of this, the microbial consortium used could resist loading rates up to 31.5 mg L−1 d−1 of ametryn, with removal efficiencies up to 97% for both herbicides. Thus, an alternative use of this consortium could be bioaugmentation, as a tool to protect the structure and function of an activated-sludge biota against ametryn or 2,4-D shock loads. The process was carried out in a lab-scale prototype of aerobic biobarrier constructed as a compartmentalized fixed film reactor with airlift recirculation of oxygenated liquid.

► A microbial consortium that degrades ametryn and 2,4-D was selected from soil.
► To retain the consortium, a novel type of biofilm reactor (PBR) was constructed.
► Both compounds, toxic for microbial communities, were degraded in the PBR.
► Six bacterial strains constituting the consortium were isolated and identified.
► The capability of each strain to degrade ametryn and 2,4-D was evaluated.