Abstract: For the biological purification of waste water that contains organic and nitrogen-containing compounds, wastewater is aerated with air and/or oxygen in the presence of a biomass fixed on a carrier material 9 in a reactor 1 through which flow takes place lengthwise and then is separated in a secondary clarification 5 into purified water and sludge. The separated sludge is at least partially returned again to the reactor 1. Carrier particles in an amount that can move freely in the waste water are introduced into the reactor as carrier material 9 for the microorganisms. To enable the decomposition of both the organic compounds and the nitrogen-containing compounds simultaneously. In the reactor 1, a cylindrical flow 10 of the mobile reactor contents is produced by aeration perpendicular to the flow direction in the reactor 1.

Abstract: Wastewater containing impurities refractory to secondary treatment is first introducted into an aerobic biological treatment stage operating with an oxygen-enriched stream and subsequently into a precipitation stage where the biologically treated wastewater is combined with Ca(OH).sub.2 to precipitate Ca(OH).sub.2 CaCO.sub.3 sludge which adsorbs or occludes impurities. The clear liquid, separated from the resultant sludge, is passed to a second precipitation stage where it reacts with a CO.sub.2 and oxygen-containing waste gas at least in part from the aerobic biological treatment stage, thereby forming additional CaCO.sub.3. Waste gas withdrawn from the second precipitation stage, being enriched in oxygen is recycled to the aerobic biological treatment stage.

Abstract: A process is provided for the removal of heavy metals from wastewater prior to being fed to a wastewater treatment installation, with anaerobic sludge to cause the anaerobic sludge to absorb heavy metals in the wastewater. Thus, the heavy metals depleted wastewaters can then be treated in a conventional treatment plant and thereafter, the resultant sludge can be directly employed for agricultural purposes without requiring further treatment to remove heavy metals therein. To effect the process a preferred reactor is made up of two parts, a cylindrical mixing tank and a superposed funnel-shaped sedimentation zone.

Abstract: This invention relates to a process and device for anaerobic decomposition of organic substrate in which organic substrate to be treated is passed in a downflow mode through a reactor (1) having a filter bed therein as a carrier for settling microorganisms. The substrate treated in filter bed (3) is partially recycled by a recycle pipe 4 from the bottom to the top of reactor (1). Produced digester gas is drawn off by a gas outlet (9) at top of reactor (1). To maintain a high volume load and to achieve high operational stability, it is provided that a partial stream of substrate treated in filter bed (3) is passed in an upflow mode through a riser pipe (11) to effect further degradation of residuals and is drawn off at the top of reactor (1) by means an outlet (10) directly from the riser pipe (11).

Abstract: In the anaerobic biological purification of wastewater containing organic substances, some of which have a low rate of metabolism in anaerobic microorganisms, e.g., undissolved and/or partly macromolecular substances, the low-rate substances are separated from the wastewater into a secondary stream, e.g., by mechanical, adsorptive or precipitating means, before introducing the mainstream of the wastewater to be purified into the reactor operated under anaerobic conditions. The low-rate substances separated in concentrated form are treated, e.g., in a separate anaerobic reactor, or in an aerobic reactor situated downstream of the anaerobic reactor.

Abstract: In a process for the anaerobic biological purification of wastewater containing organic pollutants, the wastewater to be purified is conducted through two series-connected reactors (2 and 5) operated under anaerobic conditions. In order to achieve a shortening of the residence time for the wastewater to be purified and thereby a savings in total reactor volume, the pollutants contained in the wastewater, which are present partially in the undissolved, partially in the macromolecular state and are only slowly metabolizable under anaerobic conditions, are retained in the first reactor (2) by means of a filter medium (3) arranged in the first reactor (2). On the other hand, pollutants initially present in the dissolved condition in the wastewater and which are readily degradable by anaerobic microorganisms, are further conducted directly through the first reactor, without substantial conversion, into the second reactor (5) through a connecting conduit (4).