Abstract: In a system for biodegrading oxidizable organic waste in a bioreactor in combination with a membrane ultrafiltration unit used to separate a high quality permeate from activated sludge which is returned to the bioreactor from the membrane unit as a recycle stream, it has been found that an in-line fine bubble diffuser or "micronizer" takes advantage of the kinetic energy in the recycle stream to aerate the biomass with surprising efficiency. The micronizer is positioned external to the biomass in the bioreactor; the discharge from the micronizer provides a microaerated tail-jet of the recycle stream which has been infused with a mass of air bubbles from 1-1000 .mu.m in diameter. The velocity of the compressed air flowed into the micronizer keeps its pores from clogging with sludge. The energy of the recycle stream without the air is insufficient to provide the requisite motive force for adequate oxygen transfer and to establish a predetermined recirculation pattern.

Abstract: The invention provides a new method and apparatus for measuring the concentration of ultra-violet light absorbing organic materials liquids, particularly in pure or ultra-pure water, the speed and convenience being such that it is possible to take successive readings with periods as short as ten seconds. The apparatus can be mounted directly in or as a by-pass to a process stream, giving the capability of constant monitoring with virtually instant microprocessor-controlled response to measurements outside a pre-set range. The water to be measured passes upwards in a cylindrical opaque-walled sample cell at the upper end of which is mounted an intense light source, preferably a Xenon flash tube, and at the lower end of which is mounted two transmission photodetectors, which have in front of them respective narrow-band optical transmission filters in the ultra-violet and visible regions.