Feasibility of a multi-component additive for efficient control of activated sludge filamentous bulking

Instantaneous improvement of the settling of bulking filamentous activated sludge can be achieved by the addition of a polymer or a large amount (up t o 100% of the MLSS concentration) of talc powder to the sludge. Long-term i mprovement relies on repeated additions, as these additives have no adverse effects on the causative filaments. A multi-component additive was compare d to the traditional additives in lab-scale activated sludge units using th ree highly filamentous sludges from different industrial treatment plants. The study demonstrated that the multi-component additive was superior to th e traditional remedies. It was shown that, in the case of severe filamentou s bulking, a single addition of the neu additive immediately improved sludg e settling and exerted a destructive effect on the causative filamentous ba cteria. Thus. the latter additive also ensured a long-term sludge sedimenta tion improvement. The traditional additives exhibited an immediate and shor t-term effect. The node additive also retarded sludge rising due to denitri fication and it improved sludge dewaterability. The study revealed Nostocoi dal limicola II, with slightly hydrophobic cell wall, to be somewhat resist ant to the quaternary ammonium salt present as biocide in the additive. (C) 1001 Elsevier Science Ltd. All rights reserved.