Application of Ozone in Full-Scale to Reduce Filamentous Bulking Sludge at Öresundsverket WWTP

Abstract

The return sludge of one of the four treatment lines at Öresundsverket WWTP in Sweden was subjected to ozonation in full-scale to reduce filamentous bulking sludge. The biological nitrogen and phosphorus removal capacity along with effluent parameters were studied throughout the trial. Samples were also taken to track possible changes in microbial population due to ozone. 2.8-5.0 g O 3 kg −1 treated SS −1 reduced the DSVI of the ozone-treated line from 170 to 100 mL g −1 and the reference line remained at 150 mL g −1 . No adverse effect on the biological nitrification-or the phosphorus removal rates could be detected. The microbial population of the two lines did not exhibit any substantial changes which can be correlated to ozone addition.

Impact of activated sludge ozonation on filamentous bacteria viability and possible added benefits

“…Ozone has been shown to significantly improve the settling properties of activated sludge with a dosage of approximately 5 g O 3 /kg total suspended solids (TSS) [1][2][3]. As the secondary clarifier is a critical process stage at wastewater treatment plants (WWTPs) with activated sludge, a slow settling sludge can cause major problems at WWTPs.…”

“…To alleviate the problems with filamentous bulking sludge, ozone can be applied to the return activated sludge [6,7]. Ozone applied to the return activated sludge lowers the sludge volume index and increases the settling speed of the sludge [1][2][3]. However, the mechanism by which ozone interacts with the filamentous bacteria has not been widely studied.…”

A multivariate approach of changes in filamentous, nitrifying and protist communities and nitrogen removal efficiencies during ozone dosage in a full-scale wastewater treatment plant

“…In previous studies lower ozone doses were effectively used to control filamentous bulking (1.4 to 2.8 gO3/kg SS) (Lyko et al, 2012;Nilsson et al, 2014;Ried et al, 2014;Saayman et al, 1996), than ozone dosage applied in this study. Different factors as process configuration, floc characteristics and ozone dosage point, probably influenced the observed results.…”