ANAEROBIC BIOFLOCCULATION OF WOOL SCOURING EFFLUENT - THE INFLUENCE OF NONIONIC SURFACTANT ON EFFICIENCY

Wool scouring effluent (WSE) contains high concentrations of wool grea se emulsified by non-ionic surfactants (nonylphenol polyethoxylates - NPEO). The short-term treatment (1-7 days) of this effluent with anaer obic bacteria resulted in partial grease flocculation. However the eff iciency of this process varied largely (30% to 80%) with the source of wool scouring effluent used. The concentration of free surfactant, ra ther than total surfactant, was found to be the likely reason for the variation in efficiency. In order to elucidate the mechanisms of anaer obic biological flocculation a detailed surfactant analysis was perfor med. This revealed that anaerobic microbes (taken from sludge of a mun icipal wastewater treatment plant) had an ability to partially degrade NPEO by shortening the hydrophilic ethoxylate chain causing coagulati on and subsequent flocculation of wool grease from the liquor. Copyrig ht (C) 1996 IAWQ. Published by Elsevier Science Ltd.