Exposure of activated sludge to nanosilver and silver ion: Inhibitory effects and binding to the fractions of extracellular polymeric substances.

The main aim of the study was to determine the inhibitory effects of Ag(+) and AgNP (commercial and synthesized) on activated sludge by using respirometry. Along with this aim, also the changes taking place in extracellular polymeric substances (EPS) were studied. Additionally, the binding of Ag(+) or AgNP to the different fractions in EPS was assessed using voltammetry.

Extracellular polymeric substances (EPS) and surface properties of activated sludges: effect of organic carbon sources.

The study aims to clarify how the type of organic substrate in a wastewater affects the production and composition of extracellular polymeric substances (EPS) and hydrophobicity and surface charge of activated sludges. For this purpose, three activated sludge reactors were operated in parallel with feeds composed of the organics (i) peptone, glucose, and acetate and (ii) peptone and (iii) glucose. EPS extracted from sludges were fractionated into very loosely bound, loosely bound, and tightly bound fractions and analyzed for protein and polysaccharide.

Inhibition of respiration and distribution of Cd, Pb, Hg, Ag and Cr species in a nitrifying sludge.

The study investigated the inhibitory effects of the heavy metals Cd, Pb, Hg, Ag and Cr (as Cr(3+) and Cr(6+)) on a nitrifying sludge. The aim was to assess the IC(50) concentrations leading to 50% inhibition. The method is based on respiration of nitrifying sludge in the presence of these metals.