A method for the oxidative purification of gaseous and/or liquid media comprises placing at least one completely metal catalyst with a sufficiently large surface area in a reactor filled with liquid and inert filler and/or structured packing material to form active layers and then passing a liquid mixed with hydrogen peroxide and/or a peracid through the layered composite at the same time as a gas.

Oxidative purification of gases or effluent

A process for treating an ammonia-containing wastewater, which comprises the steps of contacting an ammonia-containing wastewater A with steam C (carrier gas) in a stripping column (7) to transfer NH3 to a gas phase from the ammonia-containing wastewater A; heating the resultant gas containing NH3 in a preheater (11)and then contacting the gas with a catalyst layer (13) to decompose NH3 into nitrogen and water; measuring the NOx (or N2O) content of the gas generated in the above decomposition step; and adjusting, based on the measured values of the NOx (or N2O) content, one or more of (a) the feed rate of the ammonia-containing wastewater, (b) the NH3 content of the ammonia-containing wastewater and (c) the flow rate of the gas containing NH3 to be contacted with the catalyst layer [when the N2O content is measured, one or more of the flow rate of the carrier gas, the flow rate of an added gas such as air, and the flow rate of the part of the gas generated in the above decomposition step to be recycled to the catalyst layer]. The process is advantageous in that an extremely small amount of hazardous substances such as NOx is discharged even at the start of an apparatus for the process or when the NH3 content of a gas is considerably changed.

Process and apparatus for treating ammonia-containing waste water

The following are claimed: (A) removal of ammonium and/or ammonium-contg. cpds. from waste water, comprising: (a) opt. pre-treatment of the waste water (1) to remove solids; (b) passing the waste water to a carbon dioxide stripping step (7); (c) passing the stripped and degassed waste water to a mixing vessel (13) for increasing the pH, and passing the over-run (14) into a settling vessel (15); (c) recycling a partial stream (41) of the pptn. slurry stream (40) from the settling vessel (15) back to the mixing vessel (13); (d) stripping the waste (18) from the settler (15) in an air stripping column, in a countercurrent, with air (so that the desired enriching of the liq. phase to the desired level takes place), catalytic post-incineration of the ammonium-contg. stripping air (26) in a reactor (25) to a permissible level of toxic materials, and recycling this to the air stripping column after cooling (27) and removal of condensates (28); and (e) passing the sump (31) from the air stripping column (19), via a heat exchanger (4), to a clarification plant; (B) appts. for carrying out the above process.

Process and apparatus for treatment of waste waters

A method for treating an NH3-containing effluent water which comprises contacting an NH3-containing effluent water (A) with a carrier gas (steam C and a combustion gas F) in a stripping tower (7), to thereby transfer NH3 from the effluent water to a gas phase, heating the resultant NH3-containing gas by means of a preheater (19), and contacting the heated gas with a catalyst layer (13) in a catalyst tower (12), to thereby decompose the NH3 into nitrogen and water, wherein the concentrations of oxygen and N2O in the catalyst tower (12) are measured with measuring instruments (21) and (22) respectively and the oxygen concentration in the gas introduced to the catalyst tower (12) is controlled by a control valve (17) so as for the N2O concentration to be fallen within a given range.

Method and apparatus for treating ammonia-containing effluent water

Pulverulent fuels are gasified in the fluidised state with a mixture of gasifying agents which contains oxygen, water vapour and/or carbon dioxide. NH3 is substantially removed from the gas produced by gasification and the NH3, or some or it, is burnt, the remaining NH3 being added to the exhaust gas from the combustion. Preferably, the content of nitrogen oxides and/or NH3 in the exhaust gas from the combustion is measured and the NH3 supplied for the combustion is added in such a way that the exhaust gas has a minimum content of nitrogen oxides and NH3 after adding NH3.

Process for treating gases obtained by gasification of solid pulverulent carburants

The invention relates to a process for removing ammonia. It is provided that gaseous ammonia to be removed is fed, together with oxygen, in particular together with air, to at least one catalyst (8) which then gives off nitrogen and water. To remove ammonia from ammonia-containing waste water, in particular from the waste water of a power station, the ammonia, in a mass transfer column (2) is transferred from the water into a gas stream. A mixture of gaseous ammonia, oxygen and other gases is fed via a heat exchanger (6) and a heater (7) to the inlet of a catalyst (8). Instead of a catalyst (8), a combination of a noble metal catalyst (10) and a mixed oxide catalyst (11) can be used. Nitrogen and water are given off at the catalyst exit. To form a virtually closed gas circulation, the exit of the catalyst (8) or of the mixed oxide catalyst (11) is connected via the heat exchanger (6) and a fan (9) to the gas feedline (4) of the mass transfer column (2).

Guenter Wittrowsky

Papers

Process for removing ammonia