Operational results and experience with submerged fixed-film reactors in the pretreatment of industrial effluents

Submersed fixed-film reactors are ideal for the pretreatment of industrial effluents. The advantages lie not only in the investment costs, but also in the operating costs. The pretreatment plants can be subject to higher loads than are possible with the activated sludge process. Consequently, considerably less space is required. And, last but not least, it is also possible to treat normally non-degradable industrial effluents. The prerequisites are that system related general structural requirements are fulfilled and suitable materials are used for the fixed-film reactor. They also offer considerable advantages in terms of operation compared to the activated sludge process, since both a higher oxygen transfer rate and yield are achieved, less sludge is produced and fewer personnel are required. All in all, the upstream submerged fixed-film reactor has proven to be an extremely reliable process, requiring little maintenance, that can cope, to a far-reaching degree, with load fluctuations of all types and reduce these. As a result, the operation of downstream treatment stages is also stabilized.