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EFFECTS OF LIME (CAO) ON THE ENDOTOXIN LEVELS OF BIOSOLIDS
Citation:
HERRMANN, R. F., T. DAHLING. EFFECTS OF LIME (CAO) ON THE ENDOTOXIN LEVELS OF BIOSOLIDS. Presented at 8th Annual National Biosolids Conference Workshop, Bolger Center, Potomac, MD, October 08, 2007.
Impact/Purpose:
to share information
Description:
Lime addition is a common practice for treating biosolids in order to meet EPA 503 requirements for land application. Since this treatment kills the majority of microorganisms, will it increase the level of endotoxins present in biosolids? And, if endotoxin levels are increased, could exposure also increase during land application? Endotoxins are a component of Gram negative cell walls called lipopolysaccharide (LPS) and are released in small amounts ftom living cells. After cell death larger amounts of endotoxins are released. LPS is composed of two parts: the O-oligosaccaride; and a lipid-A component. Lipid-A is the biologically active part of endotoxins. This research is investigating the relationship between the percentage of lime added and endotoxin biological activity. The effects of 20% lime (CaO) under class A and class B conditions on pure endotoxins and biosolids will be presented. The results of lower percentage lime (CaO) experiments will also be presented along with some potential future considerations for plant operators. Endotoxin activity in this research was determined by the limulus amoebocyte lysate (LAL) method.