Abstract: A cylindrical hollow carrier for microorganisms is prepared by subjecting a nonwoven fabric having a specific gravity of not greater than 1.0 to a surface smoothing treatment at an elevated temperature of 200.degree. to 450.degree. C., then pressing with a roller to give the nonwoven fabric a thickness of 1 to 5 mm and a weight per unit area of 30 to 300 mg/cm.sup.2 and then forming the nonwoven fabrics into a cylindrical hollow shape. The carrier has a compression weight of not less than 400 g, and preferably an outer diameter of about 25 to 100 mm and a length of about 40 to 60 mm. The nonwoven fabric may be formed of 35 to 90% fibers of 50 to 600 denier and 10 to 65% fibers of 20 to 1 denier.

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: 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.