Sustainability of denitrifying bioreactors with various fill media

Abstract

Nitrogen losses from utilised agricultural areas are responsible for water quality degradation and eutrophication. Denitrifying bioreactors can be used to reduce high nitrate concentrations in agricultural runoff in situ. The main factors affecting their function are the bioreactor fill medium and process parameters such as hydraulic retention time, temperature and inlet concentration of nitrates. The paper presents the results of laboratory experiments achieved with bioreactors filled with eight different wood-based materials, namely mulch, a mixture of spruce and pine sawdust, a mixture of pine and larch bark, and chips made of oak, poplar, larch, beech, and spruce wood. A sustainability index was used to assess the impact of the bioreactor on the environment. The best results were shown by beech, mulch and poplar and were achieved with hydraulic retention times 1.6–0.7–2.2 days, respectively, and inlet NO<sub>3</sub><sup>–</sup>-N concentration of 43.1 mg/L.

Denitrification Assays for Testing Effects of Xenobiotics on Aquatic Denitrification and Their Degradation in Aquatic Environments

“…As methanol fosters denitrification [32], the same volume of methanol must be added to the control treatment, C. Wood shavings from poplar (Populus sp.) trees were used as a suitable source of easily biodegradable organic compounds in the assays [9]. However, the dissolved organic compounds released from wood shavings are acidic, potentially inhibiting denitrification [33].…”

“…Key natural sites for denitrification are organic-rich, largely anoxic sediments in rivers, wetlands, and lakes, where the interactions between different water flows and denitrifying microbes create spots of high biogeochemical reactivity [6,8]. In nitrate-loaded subsurface waters in intensively used agricultural areas, denitrifying bioreactors can be used as a cost-effective, durable, and easily maintainable technology for effective nitrate removal [5,9]. Denitrifying bioreactors are devices filled with (mostly) particulate organic material that can be installed in groundwater [10], drainage waters [11][12][13], and stream sediments [14] to optimize nitrate removal via denitrification [15].…”

Denitrification assays for testing effects of xenobiotics on aquatic denitrification and their degradation in aquatic environments

“…As methanol fosters denitrification, the same volume of the methanol has to be added to the control C. Wood shavings of poplar (Populus sp.) were used as a suitable source of easily biodegradable organic compounds in the assays (Malá et al 2017). However, dissolved organic compounds released from wood shavings are acidic, potentially inhibiting denitrification (Tate 2000;Paul 2015).…”

“…Key natural sites for denitrification are organic-rich, largely anoxic sediments in rivers, wetlands, and lakes, where the interaction between different water flows and denitrifying microbes create spots of high biogeochemical reactivity (Pinay et al 2007;Pinto et al 2021). In nitrate-loaded subsurface waters in intensively used agricultural areas, denitrifying bio-reactors can be used as cost-effective, durable, and easily maintainable technology for an effective nitrate removal (Addy et al 2016;Malá et al 2017). Denitrifying bio-reactors are devices filled with (mostly) particulate organic material which can be installed in the groundwater (Jaynes et al 2008), drainage waters (Robertson and Merkley 2009;Christianson et al 2012;Weigelhofer and Hein 2015), and in stream sediments (Elgood et al 2010) to optimize nitrate removal via denitrification (Schipper et al 2010).…”