SCR-active molecular-sieve based catalysts with improved low-temperature performance are made by heating a molecular-sieve in a non-oxidizing atmosphere with steam (hydrothermal treatment), or in a reducing atmosphere without steam (thermal treatment), at a temperature in the range of 600-900° C. for a time period from 5 minutes to two hours. The resulting SCR-active iron-containing molecular sieves exhibit a selective catalytic reduction of nitrogen oxides with NH.sub.3 or urea at 250° C. that is at least 50% greater than if the iron-containing molecular-sieve were calcined at 500° C. for two hours without performing the hydrothermal or thermal treatment.

Process for reducing the content of NOx and N2O from an input tail gas (10) of a nitric acid process, said input tail gas having a temperature lower than 400 C., the process comprising an abatement stage at least including a deN2O stage and deNOx stage and providing a conditioned tail gas (12) having a temperature greater than the input tail gas (10), wherein, prior to submission to said abatement stage, said input tail gas (10) is pre-heated to a temperature of at least 400 C. by indirect heat exchange with at least a portion of said conditioned gas (12).

Catalyst and use of the catalyst comprising a molecular sieve belonging to the ABC-6 framework family with disorder in the ABC stacking sequence essentially composed of double-six-ring periodic building units and having a mole ratio of silicon oxide to aluminum oxide from about 8 to about 60.

A central controller for completely cleaning indoor air pollution is disclosed. The central controller is disposed in an indoor space to detect air pollution and output air pollution data. Intelligence operations are implemented in accordance with the air pollution data by the central controller to determine a location of the air pollution, and a controlling instruction is intelligently and selectively issued through a wireless communication transmission to enable a plurality of physical filtration devices or a plurality of chemical filtration devices. Each physical filtration device or each chemical filtration device includes a fan and a filter element. The fan is driven upon receiving the controlling instruction to generate an airflow convection in a direction. The air pollution is removed through the filter element, so that the air pollution in the indoor space is completely cleaned to form a clean and safe breathing air state.

The invention relates to a noxious gas purificant and its preparation and purification method for removing nitrogen oxides from gas streams thereof. The preparing method is characterized in that: mixing, according to a predetermined ratio and a process, a salt of iron, manganese, cobalt, or copper, and a related derivative thereof, an alkali or alkaline substance and a related derivative thereof, water and a forming agent, so as to obtain a solid compound or mixture; drying and activating the solid compound or mixture to produce a solid product as the purificant; and introducing the purificant into a gas-solid reactor, and removing noxious gases in a gas stream by performing, in a preconfigured temperature and using the purificant, a gas-solid reaction on the harmful gases in the gas stream. The purificant can be recycled and reused.

A bio-filter system is disclosed. The disclosed bio-filter system comprises: a transfer pipe for collecting and transferring N.sub.2O generated in any one tank from among an anaerobic tank, an anoxic tank, and an aeration tank; a bio-filter unit including a carrier for removing, by means of microbial reaction, the N.sub.2O discharged from the transfer pipe; and a sewage supply member for spraying sewage into the carrier in order to provide nourishment for microorganisms to the carrier. The bio-filter unit comprises: a filter housing; an induction discharge pipe, which is installed on the lower side of the inside of the filter housing, for inducing the N.sub.2O transferred by the transfer pipe in a transverse direction and enabling same to be discharged upwardly through a nozzle; the carrier, which is disposed on the upper side of the induction discharge pipe inside the filter housing, for removing, by means of microbial reaction, the N.sub.2O discharged through the induction discharge pipe; and a sewage spraying member, which is disposed on the top of the carrier inside the filter housing, for spraying sewage supplied from the sewage supply member to the carrier so as to utilize the sewage as nourishment for microorganisms.

An exhaust gas treatment system capable of purifying exhaust gas containing moisture includes superheated steam generating pipes (20, 40) and a housing (10). The superheated steam generating pipe (20, 40) is formed of a material capable of generating heat by energization, and has a flow path (200, 400) through which exhaust gas can flow, and moisture contained in the exhaust gas flowing through the flow path is converted into superheated steam by the heat. The housing (10) is provided to accommodate the superheated steam generating pipe, is formed to allow the exhaust gas before being introduced into the flow path to flow therethrough and can preheat the exhaust gas by the heat of the superheated steam generating pipe.

Provided herein is a catalytic article including a catalytic coating disposed on a substrate, wherein the catalytic coating comprises a bottom coating on the substrate and a top coating layer on the bottom coating layer, one such coating layer containing a platinum group metal on a refractory metal oxide support and the other such coating layer containing a ceria-containing molecular sieve. Such catalytic articles are effective toward treating exhaust gas streams of internal combustion engines and exhibit outstanding resistance to sulfur.

This invention relates to methods and compositions for removing contaminants from fluids, for example, the removal of mercury contaminants by oxidation. The compositions and methods provided herein are robust and accomplish efficient removal of contaminants from fluid streams without the need for relatively expensive activated carbon. In addition, the methods and compositions of the present invention do not pose risks to the safety of workers through the injection of highly toxic, highly corrosive elemental bromine to directly oxidize the mercury. The compositions and methods of the present invention are versatile and apply to a wide range of contaminants including, but not limited to, mercury, lead, cadmium, thallium, and hydrogen sulfides. Further, the compositions and methods contained herein are capable of efficient contaminant removal over a wide range of temperatures and pressures.

Disclosed herein are a method for treating a water stream in a zero liquid discharge (ZLD) system and a ZLD system. The method includes contacting the water stream with a metal agent that reduces a nitrate contained therein to a nitrite, and introducing an amide into the water stream that reduces the nitrite to nitrogen to provide a treated water stream having a reduced nitrate concentration. The ZLD system includes a mix tank, an amide tank including an amide, and a crystallizer. The mix tank includes an inlet for receiving a water stream within the mix tank, and a container including a metal agent. The container is designed to allow the water stream to contact the metal agent. The amide tank is designed to direct the amide into the water stream, and the crystallizer is designed to receive the water stream from the mix tank.