| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for removing nitrate nitrogen by converting nitrate nitrogen in a waste liquid into gas which is easily handled and harmless, and further, a method for inexpensively purifying the waste liquid containing nitrate nitrogen. SOLUTION: The method for purifying the waste liquid includes a first process for treating an acidic waste liquid containing nitrate nitrogen under high-temperature and high-pressure conditions of, for example, at 200 to 350°C and not less than a saturation pressure, and a second process for treating under a high-temperature and a high-pressure condition same as or different from the first process after the pH of the liquid is increased, wherein a pre-process is provided which makes a neutral or an alkaline waste liquid containing nitrate nitrogen acidic before the first process according to circumstances with an organic acid-containing waste liquid such as citric acid to prepare the acidic waste liquid. COPYRIGHT: (C)2006,JPO&NCIPI |
