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Endotoxin Studies And Biosolids Stabilization Research
Citation:
HERRMANN, R. F., T. DAHLING, AND B. BROBST. Endotoxin Studies And Biosolids Stabilization Research. Presented at 2011 States/EPA Biosolids Coordinators Workshop, Cincinnati, OH, June 20 - 23, 2011.
Impact/Purpose:
To determine if low lime addition to biosolids increases the amount of endotoxin measured in the air downwind from the field site as compared to standard and no lime additions, and to compare different air sampling devices for endotoxin recovery.
Description:
This presentation has three parts; a review of bench-scale endotoxin research, a review of observations from a field scale endotoxin release study, and discussion of biosolids stabilization and characterization by PLFA/FAME microbial community analysis. Endotoxins are part of the outer membrane of the cell wall of Gram-negative bacteria, both pathogenic and non-pathogenic microorganisms. The biological activity of the endotoxin is associated with the lipopolysaccharide (LPS) they contain. Toxicity is associated with the lipid component (Lipid A) and immunogenicity is associated with the polysaccharide components. This presentation gives a brief review of research that led up to and describes a field scale study. It has been determined that at low concentrations of added lime, endotoxin levels can increase dramatically in the biosolids. This presentation will show results from the bench-scale and field-scale observations. The primary objective of the field study was to determine if low lime addition to biosolids increases the amount of endotoxin measured in the air downwind from the field site as compared to standard and no lime additions. The secondary objectives were: 1) to compare different air sampling devices (Hi-Vol, impinger, and cassette) for endotoxn recovery; 2) to investigate how lime mixed into the biosolids at the field scale affects pH and endotoxin levels. PLFA/FAME data will be presented that shows how biosolids generation methods and final disposal options can be determined by the microbial community structure present in the biosolids.