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A wastewater biofiltration model is used to assess the potential of modelling plant-sized secondary carbon removal biofilter units. Two distinct datasets collected at the Seine-Centre biofiltration plant (Colombes, France) are used. The model is first calibrated on multiple grab samples taken at different heights inside the filter media. Data from 24 hour composite samples at the unit influent and effluent over a 2 year period are then simulated. Additional data are used to estimate hourly concentration profiles from composite samples in order to correctly use both composite and grab samples during modelling. The calibrated model is in most cases able to correctly predict the general nutrient behaviour for both datasets. The results of statistical scores such as the mean error and the mean absolute error are low for soluble components and remain correct for particles during years 2008-2009. Only one parameter set containing few heavily modified values is used to obtain these results. Modelling plant-sized biofilters appears to be practical and can be useful for easily evaluating plant optimization scenarios. [ABSTRACT FROM AUTHOR]

A full-scale nitrifying biofilter was continuously monitored during two measurement periods (September 2014; February 2015) during which both gaseous and liquid N 2 O fluxes were monitored on-line. The results showed diurnal and seasonal variations of N 2 O emissions. A statistical model was run to determine the main operational parameters governing N 2 O emissions. Modification of the distribution between the gas phase and the liquid phase was observed related to the effects of temperature and aeration flow on the volumetric mass transfer coefficient (k L a). With similar nitrification performance values, the N 2 O emission factor was twice as high during the winter campaign. The increase in N 2 O emissions in winter was correlated to higher effluent nitrite concentrations and suspected increased biofilm thickness. [ABSTRACT FROM AUTHOR]

In this study, nitrous oxide (N 2 O) emissions from a full-scale denitrifying biofilter plant were continuously monitored over two periods (summer campaign in September 2014 and winter campaign in February 2015). Results of the summer campaign showed that the major part (> 99%) of N 2 O flux was found in the liquid phase and was discharged with the effluent. N 2 O emissions were highly variable and represented in average 1.28 ± 1.99% and 0.22 ± 0.31% of the nitrate uptake rate during summer and winter campaigns, respectively. Denitrification was able to consume a large amount of dissolved N 2 O coming from the upstream nitrification stage. In the absence of methanol injection failure and with an influent BOD/NO 3 -N ratio higher than 3, average reduction of N 2 O was estimated to be of 93%. The control of exogenous carbon dosage is essential to minimize N 2 O production from denitrifying biofilters, in correlation to NO 2 -N concentrations in the filter. [ABSTRACT FROM AUTHOR]