TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Material: The nitrogen oxide processing material is in powder form. The particle is obtained after regulating particle size. The mean particle diameter of particle is 1 microm to 1 mm. The particle is a porous object. The nitrogen oxide processing material further contains an Ando soil which is subjected to particle size regulation process. The mean particle diameter of the Ando soil is 1 microm to 1 mm. The compounding ratio of the particle and Ando soil is 10:1-10:100. The ratio of mean particle diameter of particle and the mean particle diameter of the Ando soil is 10:1-10:50.Preferred Process: The nitrogen oxide is generated from exhaust gas which is produced by burning of fossil fuel. The substance to be processed is contacted with nitrogen oxide processing material for 5 minutes to 7 days at 0-60degreesC. The nitrogen oxide is dissolved in solvent from exhaust gas by passing the exhaust gas through the solvent. The exhaust gas is initially contacted with a nitrogen oxide adsorbent and nitrogen oxide is adsorbed in the adsorbent. A solvent is contacted with the adsorbent and nitrogen oxide is dissolved in the solvent.Preferred Component: The substance to be processed is water containing dissolved gaseous nitrogen oxide and having pH of 3-12. The substance contains nitrogen oxide as nitrite ions. Alternatively, the substance to be processed is a waste liquid containing corrosion inhibitor, such as rust preventing agent. The solvent is water or alkaline liquid. The nitrogen oxide adsorbent comprises activated carbon.    TECHNOLOGY FOCUS - BIOLOGY - Preferred Material: The nitrogen oxide processing material contains microorganism such as silicate bacteria and/or soil microbe. The content of microorganisms in nitrogen oxide processing material is 1x10power5 - 1x10power12 piece/mg. EXAMPLE - A raw material ore containing vermiculite was classified and ground to obtain particles with mean particle diameter of 250 microm. The particles were mixed with Ando soil in the ratio of 1:1 respectively, and nitrogen oxide processing material was obtained. The material contained 5x10power9 pieces/mg of silicate bacteria. An exhaust gas from an engine was passed into a sodium hydroxide aqueous solution and nitrogen oxide in the exhaust gas was dissolved in the aqueous solution. Copper and concentrated nitric acid were added to the solution. Phosphoric acid buffer was added to adjust the pH of the solution to 7. The treated solution has chemical oxygen demand (COD) of 110 mg/liter and pH of 6.9. 100 ml of the treated solution was aliquoted in a beaker. 2 g of nitrogen oxide processing material was added to the beaker and the mixture was stirred. The supernatant liquid was collected and the concentration of nitrite ion and COD value were determined and found to be 5 mg/l and 6 mg/l respectively. The nitrogen oxide processing material (precipitate) was removed from beaker and stored for 3 days at 20degreesC in tap water. The processing material was removed after 3 days of storage and transferred to 100 ml of fresh treated solution containing nitrogen oxide. Processing of solution was carried out as above, and the concentration of nitrite ion and COD value were 5.5 mg/l and 5.5 mg/l respectively, indicating high stability and repeated usage of the processing material.