Fractionation and Characterization of Organic Matter in Wastewater from a Swine Waste-Retention Basin

Organic matter in wastewater sampled from a swine
waste-retention basin in Iowa was fractionated into 14 fractions
on the basis of size (particulate, colloid, and dissolved);
volatility; polarity (hydrophobic, transphilic, hydrophilic);
acid, base, neutral characteristics; and precipitate or flocculates
(floc) formation upon acidification. The compound-class
composition of each of these fractions was determined by
infrared and 13C-NMR spectral analyses. Volatile acids were
the largest fraction with acetic acid being the major component
of this fraction. The second most abundant fraction was
fine particulate organic matter that consisted of bacterial cells
that were subfractionated into extractable lipids consisting
of straight chain fatty acids, peptidoglycans components of
bacterial cell walls, and protein globulin components of cellular
plasma. The large lipid content of the particulate fraction
indicates that non-polar contaminants, such as certain pharmaceuticals
added to swine feed, likely associate with the particulate
fraction through partitioning interactions. Hydrocinnamic
acid is a major component of the hydrophobic acid fraction,
and its presence is an indication of anaerobic degradation of
lignin originally present in swine feed. This is the first study
to combine particulate organic matter with dissolved organic
matter fractionation into a total organic matter fractionation
and characterization.