Abstract
This paper presents the results of a pot experiment aimed at the assessment of the agronomic and economic effectiveness of ammonium sulphate from an agro bio-refinery (Bio-AS). The Bio-AS was obtained by means of the ammonia stripping process from effluent after struvite precipitation from a liquid fraction of digestate. The agronomic effectiveness of Bio-AS in a pot experiment with maize and grass in two different soils, silty loam (SL) and loamy sand (LS), was investigated. The fertilising effect of Bio-AS was compared to commercial ammonium sulphate fertilizer (Com-AS) and control treatment (without fertilisation). The crop yields were found to depend on both soil type and nitrogen treatment. Crop yields produced under Bio-AS and Com-AS exceeded those under control treatments, respectively for SL and LS soils, by 88% and 125% for maize and 73% and 94% for grass. Crop yields under Bio-AS were similar to those under the Com-AS treatment. The fertilizer use of Bio-AS affected the chemical composition of plants and soil properties similarly as Com-AS. This suggests that Bio-AS from a bio-refinery can replace industrial ammonium sulphate, resulting in both economic and environmental benefits.
Highlights
According to the International Energy Agency (IEA), biorefining is sustainable processing of biomass into a spectrum of marketable products and energy [1,2]
The ammonium sulphate solution can be used as a valuable nitrogen fertilizer
Bio-AS is obtained as a result of the ammonia-stripping process from effluent after struvite precipitation from the liquid fraction of digestate in a farm-scale bio-refinery
Summary
According to the International Energy Agency (IEA), biorefining is sustainable processing of biomass into a spectrum of marketable products (food, feed, materials, and chemicals) and energy (fuels, power, heat) [1,2]. The concept of bio-refinery results from the necessity of sustainable management of resources and promotion of efficient use of biomass. Bio-refineries correspond with the idea of the circular economy and bioeconomy [4], permitting recovery of various substances and energy from waste used for production of value-added bioproducts. Recovery of such value-added bioproducts aims at the replacement or reduction of the use of fossil fuels and excavation of natural resources necessary for their conventional production [5]. Bio-refineries can function at various agricultural-food processing plants as well as in agricultural farms with intensive animal production. Intensive organic fertilisation applied there causes pollution of drainage waters with nutrients [6,7], as well as the emission of odours, volatile organic compounds, Energies 2019, 12, 4721; doi:10.3390/en12244721 www.mdpi.com/journal/energies
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