Inhibitory effect of silver on activated sludge: effect of organic substrate and the carbon to nitrogen ratio

BACKGROUNDSensitivity of activated sludge to heavy metals may depend on the strength and type of organics in the feed. However, literature data are usually derived from systems with an unknown or variable composition. To fill this gap, this study examined whether in activated sludge systems the inhibitory effect of Ag+ depended on the carbon to nitrogen (COD/TKN) ratio and the type of organic matter in the feed.