Temperature sensitivity of nitrate removal in woodchip bioreactors increases with woodchip age and following drying–rewetting cycles

Abstract

Woodchip bioreactors are a beneficial management practice with increasing use for the sustainable reduction of nitrate in waters discharged from agriculture and urban landscapes. Previous research has shown an interaction...

Isolation and characterization of psychrotolerant denitrifying bacteria for improvement of nitrate removal in woodchip bioreactors treating agricultural drainage water at low temperature

“…Lack of efficiency in NO 3 − removal at cold temperatures is a challenge for large-scale implementation of woodchip bioreactor technologies for mitigation of agricultural N losses to the aquatic environment. 8,58 To enhance the NO 3 − removal during cold periods, which often coincide with high drainage flow, a management option is to bypass some of the inflow in order to increase the hydraulic retention time. 59 This allows time for anaerobic conditions and denitrification to establish in the woodchip bioreactor, but leaves a portion of the drainage water untreated.…”

Temperature Sensitivity and Composition of Nitrate-Reducing Microbiomes from a Full-Scale Woodchip Bioreactor Treating Agricultural Drainage Water

“…Nitrate removal may be virtually complete under conditions with high hydraulic residence time and temperature [ 9 ], but WBRs typically show annual mean efficiencies of about 50% [ 10 , 11 , 12 ]. This reflects that the NO 3 − removal efficiency may drop to 10–20% at low water temperatures (~5 °C), due to the temperature response of the woodchip microbiome [ 11 , 12 , 13 ]. This drop in NO 3 − removal efficiency is a notable drawback in climate zones where the temperature is low during the main agricultural drainage season [ 14 ].…”

Oxic–anoxic cycling promotes coupling between complex carbon metabolism and denitrification in woodchip bioreactors

“…The biokinetics of N 2 O reduction are also highly sensitive to organic carbon source (Qi et al, 2022), and it is possible that changes in the bioavailable organic carbon pool caused by ligninolytic enzyme activity early in the oxic-anoxic transition (Figure 3A) could have contributed to improved N 2 O attenuation at those times. This multi-omics investigation into coupled C and N transformations in WBRs provides an explanation for recent chemical observations of the effects of oxicanoxic cycling on WBR performance, including the multi-day enhancement of NO 3 À removal rates after dry-downs (Maxwell et al, 2019;Maxwell et al, 2020;McGuire et al, 2021). This work reveals that the primary biogeochemical function of drying-rewetting cycles was to stimulate the activity of fungal ligninolytic enzymes, rather than stimulation of GH enzymes involved in cellulose and hemicellulose degradation.…”

“…This multi‐omics investigation into coupled C and N transformations in WBRs provides an explanation for recent chemical observations of the effects of oxic–anoxic cycling on WBR performance, including the multi‐day enhancement of NO 3 − removal rates after dry‐downs (Maxwell et al, 2019; Maxwell et al, 2020; McGuire et al, 2021). This work reveals that the primary biogeochemical function of drying‐rewetting cycles was to stimulate the activity of fungal ligninolytic enzymes, rather than stimulation of GH enzymes involved in cellulose and hemicellulose degradation.…”