Achieving drinking water compliance levels for metaldehyde with an acclimated sand bioreactor

Abstract

Metaldehyde removal was delivered to below the 0.1 µg L -1 regulatory concentration in a laboratory scale continuous upflow fluidised sand bioreactor that had undergone acclimation through selective enrichment for metaldehyde degradation. This is the first reported case of successful continuous flow biological treatment of metaldehyde from real drinking water sources treating environmentally realistic metaldehyde concentrations. The impact of the acclimation process was impermanent, with the duration of effective treatment directly related to the elevated concentration of metaldehyde used during the enrichment process. The efficacy of the approach was demonstrated in continuous flow columns at both laboratory and pilot scale enabling degradation rates of between 0.1 and 0.2 mg L -1 h -1 . Future work needs to focus on optimisation of the sand bioreactor and the acclimation process to ensure viability and feasibility of the approach at full scale.

Application of activated carbon fabric for the removal of a recalcitrant pesticide from agricultural run-off

“…For example, a study of the river Thames catchment found metaldehyde peaks of up to 0.9 μg/L in surface waters (Kay and Grayson, 2014). Agricultural run-off typically Journal Pre-proof has higher pesticide concentrations than receiving surface waters, with reported peaks as high as 10 μg/L (Rolph et al, 2020). An assessment of six different pesticides in a headwater stream in an agricultural catchment saw pesticide spikes typically occurring during storm events following application of the chemicals (Ramos et al, 2017;Ramos et al, 2019).…”

“…However, the removal of pesticides from agricultural run-off is challenging for a number of reasons. Maximum pesticide peaks are typically observed following the application of the pesticide and during high intensity rainfall events (Rolph et al, 2020). Run-off events therefore have high flows, typically discharges of 10 L/s or above (Maillard et al, 2011;Xu, et al, 2015), and the water will contain a range of other dissolved substances as well as particulate debris.…”

Analyzing (Initial) Biotransformation Reactions as an Organizing Principle for Unraveling the Extent of Trace Organic Chemical Biotransformation in Biofiltration Systems

“…4,8 In contrast, strategies addressing substrate and nutrient conditions are more diverse, including maintaining a selective pressure for oligotrophic organisms, 9,10 cycling of feeding and starving conditions, 7 proper feeding of growth substrates or cosubstrates, 11 or preadaptation to increased concentrations of target chemicals. 12 To appropriately deploy strategies for the stimulation of the removal of TOrCs in biological treatment systems, we need a better understanding of dominant removal mechanisms, relevant bacteria, enzymes and cofactors, and optimum environmental conditions for enhanced TOrC biotransformation. Despite recent research efforts, our current knowledge of microbially mediated TOrC removal is still limited and results from different studies often seem contradictory.…”

“…A majority of such approaches are based on the establishment of oxic conditions as they have been identified as being beneficial for the removal of most TOrCs. , In contrast, strategies addressing substrate and nutrient conditions are more diverse, including maintaining a selective pressure for oligotrophic organisms, , cycling of feeding and starving conditions, proper feeding of growth substrates or co-substrates, or preadaptation to increased concentrations of target chemicals . To appropriately deploy strategies for the stimulation of the removal of TOrCs in biological treatment systems, we need a better understanding of dominant removal mechanisms, relevant bacteria, enzymes and cofactors, and optimum environmental conditions for enhanced TOrC biotransformation.…”