Liquid digestate treatment by means of Nitrification and Vacuum Evaporation

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This paper summarizes recent experimental results of a novel method for liquid digestate treatment: a combination of nitrification and vacuum evaporation. The paper is mainly focused on the evaporation step. The experiments were carried out in the real agricultural biogas plant using pilot nitrification and evaporation units. The two products of the technology – separated water and concentrated liquid digestate – were showing promising properties. The separated water COD was kept below 12 mg/l and NH4-N around 20 mg/l, thus allowing the water to be discharged or recycled. The volume of concentrated liquid digestate was reduced up to 50 % with majority of the nutrients (N, P, K) staying in this output stream.

This paper summarizes recent experimental results of a novel method for liquid digestate treatment: a combination of nitrification and vacuum evaporation. The paper is mainly focused on the evaporation step. The experiments were carried out in the real agricultural biogas plant using pilot nitrification and evaporation units. The two products of the technology – separated water and concentrated liquid digestate – were showing promising properties. The separated water COD was kept below 12 mg/l and NH4-N around 20 mg/l, thus allowing the water to be discharged or recycled. The volume of concentrated liquid digestate was reduced up to 50 % with majority of the nutrients (N, P, K) staying in this output stream.

liquid digestate; nitrification; vacuum evaporation

04.08.2022

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