EFFECT OF INFLUENT QUALITY VARIABILITY ON BIOFILTER OPERATION

Fixed-Film processes have been developed and are now widely used to up grade or to build wastewater treatment plants adapted to very stringen t standards, in situations where the existing technologies are unable to meet these objectives with acceptable cost and reliable operation ( Rogalla er al., 1992). Often based on daily average samples, these sta ndards may require compliance 95% of the time on grab samples. To sati sfy such requirements, the biological processes have to ensure an acce ptable outlet quality in spite of variable inlet quality and flow. In this study, the performances of the Biostyr(R) process used in the nit rification/denitrification design are assessed at very low ammonia out let residuals with different inlet variability conditions. (C) 1997 IA WQ. Published by Elsevier Science Ltd.