Understanding soluble microbial products (SMP) as a component of effluent organic matter (EfOM)

Formation of soluble microbial products (SMP) during biological degradation of organic compounds in a sequencing batch reactor (SBR) was investigated using high performance liquid chromatography—size exclusion chromatography (HPSEC) as well as other organic matter characterization tools. Results showed that carbon compounds in a glucose feed solution were totally transformed to other organic products classified biomass-associated products (BAP). The SMP–BAP contained in the SBR effluent consisted mainly of high-molecular weight (MW) fractions of organic matter, possibly originating from cell lysis. These compounds exhibited a low specific ultraviolet absorbance (SUVA) and a hydrophilic character. In addition, the characteristics of bulk effluent organic matters (EfOM) samples from wastewater treatment facilities were studied. It was observed that EfOM consisted of humic-like and hydrophobic (HPO) compounds, derived from the corresponding drinking water source, in addition to SMP–BAP. A superimposition of SEC chromatograms of the SMP–BAP and humic-like compounds represented a fingerprint of EfOM.