Thermal drying of the solid fraction from biogas digestate: Effects of acidification, temperature and ventilation on nitrogen content

Abstract

Drying of solids produced from digestate is prone to N losses through NH3 volatilisation. The applicability of acidification as an NH3 emission mitigation technique during the drying of solids from digestate was assessed in a drying experiment. Operating conditions comprised four drying temperatures (70-160 degrees C), two air ventilation rates (natural, 420 ml/min) and three pH levels (9.2, 6.5 and 5.5) of the solids, modified by the addition of concentrated sulphuric acid. Acidification of the solids from digestate significantly decreased the NH3 emission during drying, irrespective of the drying conditions. A parallel decrease in the organic nitrogen content and an increase in the ammonium content of the solids was observed after acidification of the solids. It was confirmed that acidification before thermal concentration of solids from digestate, minimised NH3 losses under a wide range of drying conditions. (C) 2015 Elsevier Ltd. All rights reserved.

Keywords

Ammonia; pH; Drying method; Hydrolysis; Organic waste

Published in

Waste Management
2016, Volume: 48, pages: 218-226
Publisher: PERGAMON-ELSEVIER SCIENCE LTD

UKÄ Subject classification

Soil Science


Publication identifier

DOI: https://doi.org/10.1016/j.wasman.2015.10.008

Permanent link to this page (URI)

https://res.slu.se/id/publ/87474