Effects of storage on characteristics and hygienic quality of digestates from four co-digestion concepts of manure and biowaste
Tutkimustuotos › › vertaisarvioitu
|DOI - pysyväislinkit|
|Tila||Julkaistu - lokakuuta 2008|
This study evaluated the effects of storage in northern winter conditions (5 °C) on the characteristics and nutrients separation of digestates from co-digestion of manure and biowaste as well as the hygienic quality of the digestates after digestion and storage. During 3-11 months' storage average nitrogen losses and reductions of total solids (TS) and volatile solids (VS) were 0-15%. With some exceptions, soluble chemical oxygen demand (SCOD) had increased slightly (from ∼6.5 to ∼7.5 g/l) after 3 months' storage, while after 9-11 months' it had decreased from 8.3-11 to 5.6-8.4 g/l. The concentrations of Ptot and PO4-P in the separated liquid fractions decreased 40-57% after 3 months' storage and 71-91% after 9 months' storage compared to the initial concentrations. The methane potential losses during 9-11 months' storage corresponded 0-10% of the total methane potential without storage. The hygienic quality of the digestates from the 55 °C reactor and during storage fulfilled the Animal By-Products Regulation (ABPR) demands while the 35 °C digestate contained 0-105 cfu/g of indicator bacteria (faecal coliforms, enterobacteria, enterococcus) and >10 cfu/g of spiked salmonella, which amounts decreased slowly during storage. Sulphite reducing clostridia was not affected by either digestion or storage.