Evaluating the degradation of the herbicides picloram and 2,4-D in a compartmentalized reactive biobarrier with internal liquid recirculation

Abstract

Tordon is a widely used herbicide formulation of 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-amino-3,5,6-trichloropicolinic acid (picloram), and it is considered a toxic herbicide. The purposes of this work were to assess the feasibility of a microbial consortium inoculated in a lab-scale compartmentalized biobarrier, to remove these herbicides, and isolate, identify, and evaluate their predominant microbial constituents. Volumetric loading rates of herbicides ranging from 31.2 to 143.9 g m(-3) day(-1), for 2,4-D, and 12.8 to 59.3 g m(-3) day(-1) for picloram were probed; however, the top operational limit of the biobarrier, detected by a decay in the removal efficiency, was not reached. At the highest loading rates probed, high average removal efficiencies of 2,4-D, 99.56 ± 0.44; picloram, 94.58 ± 2.62; and chemical oxygen demand (COD), 89.42 ± 3.68, were obtained. It was found that the lab-scale biofilm reactor efficiently removed both herbicides at dilution rates ranging from 0.92 to 4.23 day(-1), corresponding to hydraulic retention times from 1.087 to 0.236 days. On the other hand, few microbial strains able to degrade picloram are reported in the literature. In this work, three of the nine bacterial strains isolated cometabolically degrade picloram. They were identified as Hydrocarboniphaga sp., Tsukamurella sp., and Cupriavidus sp.

Electrochemical degradation of the herbicide picloram using a filter-press flow reactor with a boron-doped diamond or β-PbO 2 anode

“…7c and 7b it becomes evident that indeed recalcitrant organic species are being formed, since total COD abatement is attained at electrolysis times for which only a fraction of TOC abatement is attained. For instance, 20 for japl = 50 mA cm -2 , there is no remaining solution COD after 90 min of electrolysis, when about 50 % of the solution TOC is still existent. Most probably, the obtained COD does not reflect the solution theoretical organic demand, as discussed by Baker et al [58] for several recalcitrant organic compounds, including organochlorines.…”

“…The degradation or removal of PCL from aqueous media has been investigated using different methods ever since the end of the 1960s, with varying degrees of success: photolysis [7][8][9][10][11], photocatalysis [1,[12][13][14], Fenton reaction [15,16], photoFenton reaction [10,17], electro-Fenton reaction [4], chemical oxidation and hydrolysis [11], biosorption [18,19], and biodegradation [20]. As far as we could ascertain, although electrochemical methods have been extensively used for the electrodegradation of organics [21], the degradation of PCL has only been investigated by the electro-Fenton process [4], when 30 mg L -1 PCL solutions were degraded.…”

Evaluating the Impact of Post-Emergence Weed Control in Honeybee Colonies Located in Different Agricultural Surroundings

“…Although we did not evaluate agrochemical residues of the studied colonies, reports confirm the presence of traces of GLY and 2,4-D in honey samples [30][31][32][33], and atrazine in pollen, wax and bees [34]. Additionally, there is evidence that herbicides and their metabolites can persist more than 20 days in water and soil [70][71][72][73]. Nevertheless, there is little information available that shows the presence of GLY in honeybee brood food, such as royal jelly and wax combs [20].…”

The Enhanced and Tunable Sustained Release of Pesticides Using Activated Carbon as a Carrier

“…2,4-D sodium has the advantages of low cost, wide application, and low toxicity [35]. However, because 2,4-D sodium is highly water-soluble, it is easily washed away by rain, and the volatiles are transferred to the environment [36], which not only harms the health of non-target plants and animals, but also harms humans [37,38,39,40]. Three AC and two types of PDA-modified AC materials were chosen as the potential sustained-release carriers, and their capability for adsorption and sustained release of 2,4-D sodium was investigated.…”