PROCESS AND APPARATUS FOR TREATING AMMONIA-CONTAINING WASTE WATER

摘要

Disclosed are methods and apparatuses for treating an ammonia-containing effluent in which the amount of hazardous substances such as NOx formed at the time of starting the operation of the apparatus or even at the time when the concentration of ammonia (NH3) in the gas to be subjected to an NH3 decomposing step (described below) was changed is extremely small; in which method an NH3-containing effluent A and vapor (carrier gas) C are contacted in stripping tower 7 to transfer the NH3 from the effluent to a gas phase, a gas containing the NH3 stripped in the tower is heated with pre-heater 1 and then contacted with catalyst 13 to decompose the NH3 into nitrogen and water, the concentration of the NOx (or N2O) contained in the gas resulted at the NH3 decomposing step is determined, and one or more of parameters (a) the amount of the effluent to be supplied to the stripping step, (b) the concentration of the NH3 contained in the effluent, and (c) the flow rate of the NH3-containing gas contacted with the catalyst (when the N2O concentration was determined, one or more of (e') the flow rate of the carrier gas, (f') the amount of a gas such as air to be added to the NH3-containing gas, and (g') the amount of a part of the gas resulted at the NH3 decomposing step and to be circulated) are adjusted responding to the concentration of the NOx (or N2O).