Assessment and mitigation of the environmental burdens to air from land applied food-based digestate

Abstract

Highlights:· In situ air pollution assessment of land applied digestate is performed. · Environmental burden minimisation scenarios for digestate bio fertiliser presented. · Food-based digestate show high ammonia volatilisation potential. · Soil incorporated digestate effectively reduces NH 3 but elevates N 2 O emissions. · Managing digestate emissions mitigate both climate change and air pollution. Abstract (limit 150 words only)Anaerobic digestion (AD) of putrescible urban waste for energy recovery has seen rapid growth over recent years. In order to ascertain its systems scale sustainability, however, determination of the environmental fate of the large volume of digestate generated during the process is indispensable. This paper evaluates the environmental burdens to air associated with land applied food-based digestate in terms of primary pollutants (ammonia, nitrogen dioxide) and greenhouse gases (methane and nitrous oxide). The assessments have been made in two stages -first, the emissions from surface application of food-based digestate are quantified for the business as usual (BAU). In the next step, environmental burden minimisation potentials for the following three mitigation measures are estimated -mixed waste digestate (MWD), soil-incorporated digestate (SID), and post-methanated digestate (PMD). Overall, the mitigation scenarios demonstrated considerable NH 3 , CH 4 and N 2 O burden minimisation potentials, with positive implications for both climate change and urban pollution. Keywords: anaerobic digestion; bio fertilizer; digestate; environmental burdens; OFMSWCapsule abstract: In situ monitoring and analyses demonstrate the role of post-processing in greenhouse gases and air pollution mitigation from food-based digestate use as bio fertiliser. Highlights:· In situ air pollution assessment of land applied digestate is performed. · Environmental burden minimisation scenarios for digestate bio fertiliser presented. · Food-based digestate show high ammonia volatilisation potential. · Soil incorporated digestate effectively reduces NH 3 but elevates N 2 O emissions. · Managing digestate emissions mitigate both climate change and air pollution.3

Advanced Processing of Food Waste Based Digestate for Mitigating Nitrogen Losses in a Winter Wheat Crop

“…Although more experiments under different weather conditions, physico-chemical soil properties and crops are necessary, our study supports the use of acidification of food based digestate, consistent with this technique being called the Best Available Technology (BAT) for reducing NH 3 losses from slurries in some countries (Kai et al, 2008). Rapid soil incorporation has also been shown to reduce NH 3 losses by up to a 85% when following application of food waste based digestate (Tiwary et al, 2015) but it could increase N losses in the form of N 2 O as observed for slurries (Thorman, 2011).…”

“…Tiwary et al (2015) reported that 35-65% of the total N applied in digestate can be lost through NH 3 volatilization if the digestate is surface broadcast. Potential methods to reduce NH 3 volatilization include the rapid incorporation of manures and digestates into the soil after application (Möller et al, 2008;Tiwary et al, 2015), soil injection (Riva et al, 2016), bandspreading (Nicholson et al, 2017), and acidification of slurries (Fangueiro et al, 2015a).…”

“…However, there are contradictory reports from the literature (Möller, 2015) suggesting that emissions are related to the feedstocks and soil properties to which they are applied, e.g., soil organic matter content, soil texture, water content, and aeration (Chantigny et al, 2009;Eickenscheidt et al, 2014). Reported N losses as N 2 O emissions following the application of food-based digestate vary from 0.45% (Nicholson et al, 2017) to 4-10% (Tiwary et al, 2015) of the total N applied. A method to reduce N 2 O emissions from manure applications, which may be equally applicable to digestates is the use of nitrification inhibitors (NI), such as 3,4-Dimethylpyrazole phosphate (DMPP) (Owusu-Twum et al, 2017), that delay the process in which NH + 4 transforms into NO − 3 .…”

“…The main concerns regarding application of digestate and other organic wastes to agricultural land are emissions of N to the environment through ammonia (NH 3 ) volatilization, nitrate (NO − 3 ) leaching and greenhouse gas emissions as nitrous oxide (N 2 O), with associated impacts on air and water quality, ecosystem functioning and human health (Galloway et al, 2003). Tiwary et al (2015) reported that 35-65% of the total N applied in digestate can be lost through NH 3 volatilization if the digestate is surface broadcast. Potential methods to reduce NH 3 volatilization include the rapid incorporation of manures and digestates into the soil after application (Möller et al, 2008;Tiwary et al, 2015), soil injection (Riva et al, 2016), bandspreading (Nicholson et al, 2017), and acidification of slurries (Fangueiro et al, 2015a).…”

Efficient use of nitrogen in agriculture

“…Digested organic material, which has been used for biogas production, is a valuable form of organic fertilizer (Abubaker et al 2012;Nkoa 2014). However, the application of biogas residues as fertilizer might be associated with enhanced NH 3 emissions (Tiwary et al 2015). Nicholson et al (2018) tested different digestates and application techniques in a temperate grassland to identify fertilization approaches that minimize NH 3 emissions.…”