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Maximizing phosphorus and potassium recycling by supplementation of lignin combustion ash from dry biorefining of lignocellulose

Liu, Gang, Bao, Jie
Biochemical engineering journal 2019 v.144 pp. 104-109
agricultural land, biogeochemical cycles, biomass, biorefining, byproducts, combustion, electricity generation, ethanol, ethanol fuels, fertilizer application, lignin, lignocellulose, market prices, nutrients, phosphates, phosphorus, phosphorus fertilizers, potassium, potassium fertilizers, soluble phosphorus, wastewater, China
Lignocellulose biorefinery produces fuel ethanol and lignin residue byproduct. The combustion ash of lignin residue after electricity generation contains high amount of phosphorous and potassium elements and the recycling to farmland provides a sustainable nutrients supply. This study demonstrated a maximum scenario of water- soluble phosphorous and potassium recycling through a dry biorefining process by reduction of wastewater generation to an extremely low level, in which the soluble phosphorus and potassium compounds were preserved. For biorefining one metric ton of five different lignocellulose biomass, averagely 51–87 kg of lignin combustion ash, 0.75–1.12 kg of phosphorous or equivalent 1.75–2.57 kg of P2O5, and 1.03–2.26 kg of potassium or equivalent 1.24–2.73 kg of K2O were obtained. The recycling of the ash to farmland covered 78–90% and 100% (with surplus) of the world average phosphate and potash fertilizer use, respectively. Even for the need of farmland in China with the heavily overused phosphate and potash fertilizers, the lignin combustion replaced 17–19% of phosphate fertilizer and 30–70% of potash fertilizer. The minimum ethanol selling price was also reduced by 2.1–3.3% by the fertilizer replacement.