Abstract: A solid-liquid separator and a process for washing the same wherein SS (sended solids) caught in space portions of a filter medium in a tank are caused to flow out from the space portions and be suspended while at least part of the filter medium is maintained in a fluidized state by air washing, and rapid drainage through a lower portion of the tank causes the SS in the suspended state to be rapidly removed without being again caught into the space portions of the filter medium.

Abstract: A waste water treatment process wherein an iron contactor or iron contact are immersed in a treatment tank, into which waste water flows. In the treatment tank sulfate reducing bacteria are made to coexist with activated sludge or biofilters, wherein a velocity of flow of agitating stream on the outer surfaces of said iron contactor or contactors is set at 10 to 20 cm/sec, under an aerobic treatment. Iron ions are made to elute from said iron contactor or contactors by utilizing electrochemical iron corrosion through the agency of oxygen concentration cells on the outer surfaces of said iron contactor or contactors on conditions that dissolved oxygen concentration in the treatment tank is 1 to 3.2 mg/l and the oxidation-reduction potential is -200 to -400 millivolts (mV). Under an anaerobic treatment, iron ions are made to elute by utilziing microorganism-corrosion on the outer surfaces of said iron contactor or contactors on condition that dissolved oxygen concentration in the treatment tank is 0 mg/l.

Abstract: A process for treating organic waste water in which a first step provided the stage precedent to a second step using an aerobic filter bed employs an upward flow type solid-liquid separator packed with a filter medium, with the SS (suspended solids) removal at the preceding stage being performed at a high SS removal rate and in a short time.

Abstract: An apparatus for directly monitoring microorganisms present in a liquid crises a window glass with one face in contact with the liquid. Near the other face is disposed a TV camera having an optical magnifying system for monitoring the microorganisms. A sample cell or a narrow space is formed on said one side of the window glass for direct introduction of a sample of the liquid. The sample is statically held in the cell even though the liquid is in movement. The sample is purged from the cell by feeding a cleaning fluid thereinto or by vibrating or otherside exerting physical movement on the cell, whereafter a new sample is introduced into the cell. Purging of the sample cleans the cell and is prevents it from being smudged with dregs, dirt or the like included in the liquid.

Abstract: A method of removing nitrogen and phosphorus from waste water by using an activated sludge including aerobic bacteria is disclosed. The waste water is fed continuously and gradually into a treatment basin in which the sludge is contained so that a mixed liquor consisting of the waste water and the sludge is formed therein. A cycle consisting of an agitating step and an aerating step is repeated at least two times and each cycle is finished within two hours, with the ratio of the agitating time to the aerating time being between one to one and to one. In the agitating step, the mixed liquor presents an anoxic condition and a succeeding anaerobic condition. Denitrification occurs in the anoxic condition and the aerobic bacteria release phosphorus in the anaerobic condition. During the aerating step, nitrification is caused while the bacteria excessively ingest phosphorus from the mixed liquor.

Abstract: Filtering apparatus comprising a stationary housing and a rotary filter d having a peripheral filter screen with elongated filter openings extending parallel to an axis thereof and disposed within the housing to define a space between the filter drum and the housing. A sludgy liquid supply means is provided for supplying the sludgy liquid from the inside of the filter drum onto the inner surface of the filter screen. Solid component adheres to the filter screen and liquid component passes through the elongated filter openings of the filter screen into the space, said solid component on the filter screen being discharged from the interior of the filter drum through the housing in the form of aggregations of filtration residue and said liquid component being discharged from the space through an outlet opening as filtrate.