Effect of influent quality variability on biofilter operation

Fixed-film processes have been developed and are now widely used to upgrade or to build wastewater treatment plants adapted to very stringent standards, in situations where the existing technologies are unable to meet these objectives with acceptable cost and reliable operation (Rogalla et al., 1992). Often based on daily average samples, these standards may require compliance 95% of the time on grab samples. To satisfy such requirements, the biological processes have to ensure an acceptable outlet quality in spite of variable inlet quality and flow. In this study, the performance of the Biostyr® process used in the nitrification/denitrification design are assessed at very low ammonia outlet residuals with different inlet variability conditions.