(DE4124900-A)      Continuously biologically acting on a target chemical in an aq. stream comprises: 1) cultivating bacteria under non-growth-limiting conditions; 2) exposing the cultivated bacteria to mutation producing ultra violet-light, 3) exposing the mutated bacteria to the target chemical under growth limiting conditions.    Also claimed is a process comprising digesting sludge in a biological reactor and an apparatus for continuously biologically acting on a target chemical in an aq. stream.    USE/ADVANTAGE -   Useful for acting on halogenated organic cpds. in an aq. stream such as an industrial waste stream. The continuous process can be operated to optimise the various steps and permits injection of the bacteria even into streams, from which they are flushed out at a higher rate than they can grow. Large number of mutants are produced and automatic screen enables best strain at lower volumetric requirement to be selected.    (FR2665180-A)      Continuously biologically acting on a target chemical in an aq. stream comprises: (1) cultivating bacteria under non-growth-limiting conditions; (2) exposing the cultivated bacteria to an ultraviolet-light source, (3) exposing the mutated bacteria to the target chemical under growth-limiting conditions.    Also claimed is a process comprising digesting sludge in a biological reactor and an apparatus for continuously biologically acting on a target chemical in an aq. stream.    USE/ADVANTAGE -   Useful for acting on halogenated organic cpds. in an aq. stream such as an industrial waste stream. The continuous process can be operated to optimise the various steps and permits injection of the bacteria even into streams from which they are flushed out at a higher rate than they can grow. Large number of mutants are produced and automatic screen enables best strain at lower volumetric requirement to be selected.    (GB2247012-B)      A method of continuously biologically degrading a target chemical in an aqueous stream comprising (1) continuously cultivating bacteria under non-growth-limiting conditions in a reactor; (2) continuously withdrawing replicating bacteria from said reactor and exposing said replicating bacteria to mutation-producing ultraviolet light to produce mutated bacteria; and (3) continuously cultivating said mutated bacteria in the presence of said target chemical under growth-limiting conditions.