Organic matter extracted from activated sludge with ammonium hydroxide and its characterization

Abstract

In order to characterize the organic properties of waste activated sludge in a wastewater treatment plant, organic matter within sludge was extracted with NH 3·H 2O preferentially, and subsequently fractionated into five fractions using XAD-8/XAD-4 resins. Up to a 63.8%–71.1% of organic matter within the sludge could be efficiently extracted by NH 3·H 2O. Fractionation results showed that hydrophobic acid and hydrophilic fraction were two main components among the sludge organic matter (accounting for 32.2% and 48.0% of the bulk organic matter, respectively), whereas transphilic acid, hydrophobic neutral and transphilic neutral were quite low (accounting for 9.2%, 5.8% and 4.8%, respectively). Despite that the extractant of NH 3·H 2O showed a relatively higher extraction efficiency of the aromatic components, the relatively low aromaticity of the organic fractions implied that those non-aromatic components could also be effectively extracted, especially for neutral and hydrophilic fractions. In addition, acidic fractions contained more aromatic humic-like components, whereas the neutral fractions had a greater content of aromatic proteins and soluble microbial byproduct-like components. Extraction of sludge organics with NH 3·H 2O and subsequential fractionation using XAD resins could be a novel method for further characterization of sludge organics.