In the conversion of wastewater treatment plants to nitrification, asid the expansion of existing nitrification tdilities to treat higher flows, available space is oñen a major concern. High-rate altached-growth processes, such as biological acrated filtration (biofiltration), are particularly well—suited for these applications.
Due to the significantly higher growth tate of heterotrophic bacteria responsible for removal of organic poflutants compared with nitriying autotrophic bacteria, sucient biodegradable organics removal musE occur before nitrification is possible. Extensive pilot scale testing asid evaluation of fiull-scale fixed bed attached-growth systems have shown that increased hydraulic loading has a positive effect on process kinetics (Peladan, al aL. 1996). Therefore, separation of organics removai ami nitrification iii staged biofilter reactors, operating at high hydraulic loading tales, results in the rnost efficient asid compact fácility.
This paper presents and discusses resuits from experiments which demonstrate the influence of biodegradable organic carbon loading and hydraulic loading on biofilter nitrification capacity. Results from a two-stage upflow biofilter pilot at Arlington County, Virginia for nitrification are reviewed.