Abstract: In apparatus for purifying waste water with activated sludge deposited on carrier particles, in which air is introduced into a treating tank for circulating the waste water and the carrier particles in the tank through an air lift, a separator is provided at an upper end of the tank for discharging purified water together with sludge peeled off from the particles thus leaving bared carrier particles in the tank for recirculation. A portion of the bottom of the tank is inclined to prevent precipitation of the activated carrier particles. The tank has a rectangular cross-sectional configuration to enable to arrange a number of tanks in a juxtaposed relation in series or parallel in a narrow floor space.

Abstract: A nitrogen fertilizer manifesting fungicidal property against Pathogenic fungi contains as its effective component a water soluble initial condensation product prepared by causing formaldehyde to react with urea. The fertilizer may be admixed with one or more of other fertilizers of various types.

Abstract: Particles of active carbon which have been used to purify contaminated liquid are regenerated by charging the particles between spaced electrodes in a furnace and passing electric current between the electrodes to thereby heat and regenerate the active carbon by the heat generated by the specific resistance of the particles and the contact resistance therebetween.

Abstract: In a vertical electric furnace having vertically spaced annular electrodes for regenerating used activated carbon by passing electric current therethrough, the inner cross-sectional area of the furnace is gradually decreased and then gradually increased between the electrodes thus forming a throat. With this construction, layers of the used activated carbon in which the resistance value varies with the temperature gradient are formed.