Microbiology of a biological contactor for winery wastewater treatment

Winery wastewaters are characterised by large seasonal fluctuations in volume and composition and are often discarded with little or no treatment. A rotating biological contactor (RBC) was used to investigate microorganisms associated with the biological treatment of winery wastewater. Extensive biofilms developed on the RBC discs and contained a number of yeast and bacterial species that displayed a dynamic population shift during the evaluation period. This suggested that the naturally occurring microorganisms were able to form a stable biofilm and also reduce the chemical oxygen demand (COD) of winery wastewater (on average 43% with a retention time of I h). One of the yeast isolates, MEA5, was able to reduce the COD of synthetic wastewater by 95% and 46% within 24 h under aerated and non-aerated conditions, respectively. The yeast isolates could therefore play an important role in the degradation of organic compounds under aerobic conditions, such as those associated with an RBC. (C) 2003 Elsevier Ltd. All rights reserved.