Abstract: An improvement in an apparatus for continuous biological treatment of waste water including a reactor having a feeding pipe and a distribution pipe at the top thereof for introducing waste water into the reactor, and a withdrawing pipe at the bottom thereof for removing treated water, and a particulate carrier having microbes attached thereto disposed within the reactor. The carrier is a particulate material having an apparent specific gravity smaller than the specific gravity of water, making it possible for the particulate material to float on water. A substantially fluidized bed of the carrier is formed by the buoyancy of the particulate material in the downflowing waste water to be treated.

Abstract: Apparatus for liquid/solid contact including apparatus for single or multiple fluidized beds provided with one or more trays having a number of inverted frustum-shaped depressions with an opening located therein.

Abstract: This invention relates to biological treatment of waste water using a carrier floatable on water, and more particularly to a novel process for treatment of waste water utilizing a fluidized bed which is formed by supplying waste water in a downflow operation. The process for treatment of waste water of this invention is applicable to both anaerobic and aerobic biological treatment. A good example of the former anaerobic biological treatment to which this invention is applicable is the process wherein the nitrate or nitrite nitrogen which is one of the nitrogen compounds that are at present believed to be one cause of the eutrophication in rivers, lakes, seas, etc. is treated with denitrifying bacteria in an anaerobic condition to be released in the form of nitrogen gas, and the typical of the latter aerobic treatment is the practice in the utilization of the action of the aerobic bacteria which can oxidize organic substances in sewage, industrial waste waters, etc.

Abstract: Spent activated-carbon is fluidized and directly heated at a temperature of 100.degree. to 700.degree. C in the first zone with an off gas from the second zone to remove volatiles from the spent carbon. The carbon so treated is then indirectly heated in the second zone at a temperature of 500.degree. to 1000.degree. C in the substantial absence of oxygen with a combustion gas while being fluidized with steam or a steam-containing inert gas to activate the carbon. The process ensures effective utilization of heat energy and substantially reduces the loss of carbon.