The swim-bed technology is an innovative and highly efficient wastewater treatment process developed by Networking of Engineering and Textile Processing Limited Corporation

Japan.The technology uses a novel biofringe attachment material

which allows for attachment of large amount of biomass on a flexible matrix in a fixed position. By this approach

flexing of the matrix induced by wastewater flow creates a swimming motion

which enhances mass transfer and improves the activity of the biomass. In this paper biological nitrogen removal from petrochemical wastewater was investigated by using an anoxic-oxic swim-bed reactor. The study result showed that good biological nitrogen removal was achieved in the reactor. The influence of mixed liquid recycle ratio and influent load on biological nitrogen removal was discussed. When mixed liquid recycle ratio

influent COD concentration and NH+4-N concentration were 2.5

400～600 mg8226;L-1 and 20～40 mg8226;L-1 respectively

the concentration of COD

NH+4-N and TN in the outlet were lower than 40 mg8226;L-1

1.0 mg8226;L-1 and 7.0 mg8226;L-1 respectively

and COD removal efficiency

nitrification rate and denitrification rate were 90%

95% and 70% respectively.