Mass balance and performance of common digestate mechanical separation equipment and fertilizing-value typology of liquid and solid fractions

International audience; Whether to enhance nutrients management for land spreading or as a previous-step for advanced treatments, digestate mechanical phase separation is present in many Anaerobic Digestion (AD) plants. A wide range of equipment is available including screw presses, centrifuges, belt presses and rotary drums. Up-to-date, few or maybe no study has critically regarded a database of digestate separation efficiency, mass balances and quality of outputs for different separators. To fill-up this gap, data from literature was gathered with an INRA’s database and operational data from SUEZ. From this database, two different analysis approaches were carried out. The first consisted to perform clustering analysis on complete fertilizing-value data of liquid fractions (LF, n = 38) and solid fractions (SF, n = 47) separately. The second approach consisted to calculate mass balances and separation efficiency indicators [1] when characterization of raw digestate and its associated LF and SF were available. The later consisted in digestate data from over 50 industrial scale digesters. The first approach resulted in a typology for LF (Figure 1A), and SF (Figure 2B). LF and SF were observed to be grouped according to AD feedstock (fibrous/non-fibrous) and separation equipment (low/high performance), with significant distinct fertilizing-values. The second analysis approach is still ongoing. Early results highlight the distinguishable performances of previously observed groups. A recurring lack of consistency on the mass balances of some elements such as nitrogen is observed and will be discussed.