Abstract: A gas sparger produces an intermittent flow of bubbles even if provided with a continuous gas flow. The sparger has a housing to collect a pocket of gas and a conduit to release some of the gas from the pocket when the pocket reaches a sufficient size. Optionally, a cover over an outlet from the conduit may break up or distribute the released gas. A large sparger for use with a commercial membrane module can comprise a plurality of smaller units.

Abstract: A membrane supported biofilm apparatus has a plurality of hollow fiber gas permeable membranes in a tank containing water to be treated. The membranes have an outside diameter of about 200 microns or less and occupy between 0.5% and 4% of the tank volume. A biofilm supported on the membranes occupies between about 40% and 80% of the volume of water to be treated in a reactor. The membranes may be oriented generally vertically and a spreader may be located near the bottom of the apparatus to disperse the membranes. Wastewater treatment processes are described. A process to dentrify water or treat oxidized contaminants comprises introducing hydrogen into an inner volume of the membranes to grow autotrophic organisms in the biofilm near the membrane and heterotrophic organism near the water. Another process is operated at a biomass concentration of at least 10 g/L and up to about 40 g/L to maintain a biofilm having a surface area of over 1000 square metres per cubic metre of tank volume.