Ultraviolet irradiation apparatus for disinfecting liquids of high ultraviolet absorptivities

A nozzle was used to generate freely supported totally enclosed thin liquid films, known as ‘liquid bells’, from suspensions of Escherichia coli in water and humic acid solutions. Disinfection was achieved by continuously recirculating the liquids to the nozzle and irradiating the bells generated with ultraviolet light. The absorptivities at 254 nm of the liquids treated ranged from 0.18 to 4.0 and after 30 min treatment E. coli viability, expressed in terms of surviving fractions, was reduced to 1.88 times 10‐5 and 1.84 times 10‐4 respectively.