Climate change effects on denitrification performance of woodchip bioreactors treating agricultural tile drainage

Israel, Joshua A.; Zhang, Zihao; Sang, Yi; McGuire, Philip M.; Reid, Matthew C.

doi:10.1016/j.watres.2023.120202

Cited by 7 publications

(15 citation statements)

References 54 publications

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“…Effluent NO 3 – concentrations (mg N/L) were modeled using N effluent , i , model = N influent , i − k 0 ( T ) HRT true̅ i where k 0 ( T ) is the temperature-sensitive zero-order rate constant [mg NO 3 – –N L –1 h –1 ]. Details on the estimation of k 0 ( T ) are available in Israel et al This model-based N effluent was then used to determine model-based NRE and NRR by using eqs and .…”

Section: Methodsmentioning

confidence: 91%

“…Woodchip bioreactor performance is typically poor during cold periods or storm events, ,,,− and here we evaluated the use of biostimulation of microbial denitrification with exogenous carbon to improve NO 3 – removal during these critical times. ,, Several studies on exogenous carbon dosing of WBRs have been performed in recent years (Table ) and have shown that C dosing is effective at increasing NRR. Our results confirm the potential of C dosing to increase NRR up to 5-fold relative to “baseline” conditions, and we quantified an improvement in cumulative N load reduction from 11.3% (under a model-based “baseline” scenario) to 24.1%.…”

Section: Discussionmentioning

confidence: 99%

“…In an earlier study, we used bromide tracer tests to determine the effective porosity of the bioreactors to be 0.8. 15 The bioreactors were filled primarily with ash woodchips (genus Fraxinus) 9 and enclosed with an impermeable polyethylene sheet. The woodchip matrix in the control reactor was originally amended with 10% biochar by weight by researchers originally interested in effects of biochar on pesticide removal in tile drainage.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…One reactor was designated the Experimental Reactor and was used to test acetate dosing, and the second reactor was designated as the Control Reactor and was operated without acetate dosing except from May 14 to 15, when acetate was injected into the inlet control structure to ensure complete mixing of the injected acetate. Both bioreactors are 6.1 m long × 3.1 m wide and treat tile drainage with a NO 3 – –N concentration between 8 and 9 mg N/L . The experimental reactor woodchip bed was 0.69 m thick, while the control reactor’s woodchip bed was 0.74 m thick.…”

Section: Methodsmentioning

confidence: 99%

“…Two key problems for the effective field-scale performance of denitrifying WBRs are (1) cool water temperatures can decrease microbial reaction rates, which is especially problematic in the Upper Midwest and Northeast U.S., where water temperatures can be low for much of the year, and (2) high-flow periods, including spring snowmelt and storm events, lead to short hydraulic retention times (HRTs) that limit NO 3 – removal efficiencies . A large fraction of NO 3 – loads exported from tile drains to agricultural watersheds is driven by storm events, so improving N removal during high-flow (and short HRT) periods is a priority for agricultural nutrient management.…”

Section: Introductionmentioning

confidence: 99%

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Real-Time Control of Exogenous Carbon Dosing in a Denitrifying Woodchip Bioreactor Treating Agricultural Drainage

Zhang,

Echavarria,

Sang

et al. 2024

ACS EST Eng.

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Nature-based treatment technologies such as denitrifying woodchip bioreactors (WBRs) are employed to manage nitrogen (N) pollution from agricultural nonpoint sources. Due to variability in environmental conditions like temperature and discharge, it is challenging to achieve consistent treatment effectiveness with these passive systems. To improve nitrate (NO 3 − ) load reductions in a field-scale WBR in New York State during cool spring weather, we designed a system for controlled exogenous carbon (C) dosing, allowing rates of C dosing to respond in real time to changing discharge and NO 3 − concentrations. Treatment efficiencies for NO 3 − , acetate mass balances, and other bioreactor properties were monitored from April 5 to June 10, 2023. Biostimulation with 7.5 mg C/L acetate (assuming complete mixing of injected acetate with bioreactor pore water) increased NO 3− removal rates up to 5-fold compared to a model-based scenario of baseline bioreactor performance, and were as high as 0.4 mg NO 3 − −N L −1 h −1 while water temperatures were <12 °C. Increasing acetate concentrations beyond 7.5 mg C/L did not confer a clear improvement in NO 3 − removal rates. Cumulative N load reductions increased from 11.3% under the baseline scenario without C dosing to 24.1% with C dosing. The mass ratio of metabolized C to additional N removal was 2.5:1, although the total dosed C/N mass ratio was 5.1:1 due to incomplete acetate utilization in the reactor. We found evidence that C dosing could enhance the future release of dissolved organic N (DON) and dissolved organic C related to biofilm sloughing. The expense of acetate, with a cost efficiency of 86 USD/kg N, was the main cost driver of the real-time control approach. Our results demonstrate the potential of real-time control of C dosing to meaningfully improve nonpoint source N removal during cool spring conditions but also highlight opportunities for methods to improve acetate utilization efficiencies in order to improve the overall cost-effectiveness of the approach.

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