Abstract: Reduction of the hysteresis effects in a gaslift loop reactor is effected with a draft tube for solids suspension. The gas or liquid flow rates for generating complete solid suspension are significantly higher than the flow rates necessary for maintaining that state. These hysteresis effects may be significantly reduced and a substantial reduction is obtained for the energy necessary to obtain the state of suspension. Preferably a draft tube which comprises openings through which an extra circulation takes place especially during the startup phase is used.

Abstract: The invention provides a process for the removal of sulfur dioxide from waste gas, comprising the steps of:a) contacting the waste gas with a basic aqueous solution wherein sulfur dioxide is dissolved as sulfite;b) subjecting the aqueous solution containing sulfite to sulfur reducing bacteria in an anaerobic reactor wherein sulfite is reduced to sulfide;c) subjecting the aqueous solution containing sulfide to sulfur oxidizing bacteria in the presence of a limiting amount of oxygen in a reactor wherein sulfide is oxidized to elemental sulfur;d) separating the elemental sulfur form the aqueous solution; ande) recycling the aqueous solution to step a).

Abstract: To avoid considerable vertical and horizontal flows in the settler formed by gas collection hoods, of the upflow anaerobic sludge blanket (U.A.S.B.) reactor, each gas collection hood (3) debouches at one or two ends into a gas collection chamber (8) via one or more openings (19), the upper boundary of said openings being situated below the inside surface of the projection or the top of the hood (3) concerned. The gas collection hoods are situated immediately below the level of the effluent discharge and the depth of the settler is shallow. As a result of the decrease in pressure only a few gas bubbles are consequently liberated and the settling of the sludge is not appreciably disturbed.

Abstract: Apparatus for purifying water containing material dissolved and/dispersed therein. The apparatus comprises an upflow reactor in which, while maintaining a sludge blanket, the water to be purified can be contacted with one or more agents bringing the dissolved and/or dispersed material into a form in which it can be separated from the water; means for the discharge of the purified water from the apparatus; and an influent distributing system to be connected to a central water supply system. The influent distributing system includes a plurality of tube members assembled to form one or more strings. The strings have outlet openings through which the water to be purified can be introduced into the reactor space at a plurality of spaced locations.

Abstract: In order to achieve an essentially turbulence-free zone near the means (11) for the discharge of purified water in an anaerobic purification plant for waste water with a fermentation chamber, a settler disposed above the latter and the said discharge means (11) disposed above the settler, the settler consists of three levels of gas-collection hoods (2, 3, 4), each gas-collection hood of the uppermost level (4) being sited directly above a gas-collection hood of the lowermost level (2), each gas-collection hood of the lowermost level (2) being connected via one or more pipes with a gas-collection hood of the uppermost level (4), and the gas-collection hoods of the uppermost and middle level (4 or 3 respectively) having a direct connection to the gas-discharge line (15).

Abstract: A considerable portion of the gas developed by fermentation in an anaerobic purification equipment for waste water, together with buoyant sludge, is collected by at least one additional collecting system (5), before it may reach the upper part of the reactor. This additional collecting system is fitted at a distance below the collecting system (6) fitted as usual just below the level of one or more overflow gutters (3; 23) for purified water. The additional collecting system (5) has a hydraulic link with one or more rising pipes (7, 7', 27, 32, 31) for raising the liquid sludge mixture by gas lift action. The rising pipes discharge into a separation device (8) from which one or more downpipes (9; 29) for returning separated liquid and sludge extend to the lower section of the reactor chamber. As a result of the tranquility at the top and the turbulence near the bottom, a substantial increase of the load capacity of the equipment can be obtained.