(215g) Study On Supercritical Water Oxidation of Quinoline Wastewater

Complex N-containing organic wastewater, which is hazard and will cause serious environment problems, is increasingly generated from industry. Quinoline is a typical N-containing compound, which is highly refractory. Supercritical water oxidation (SCWO) is a forthcoming technology for the treatment of wastewater containing non-biodegradable compounds. In this paper, the supercritical water oxidation of quinoline was investigated with hydrogen peroxide as oxidant.

  The operating conditions of SCWO process were studied by the response surface methodology (RSM) and central composite design (CCD). The effects of temperature, pressure, residence time and excess oxidation ratio on the organics removal were investigated. The optimum condition for the wastewater treatment was obtained. The optimum temperature, pressure, residence time and excess oxidation ratio were found to be 441℃, 25MPa, 60s and 2.48 respectively.

  The liquid and gas products were analyzed after experiment. The carbon of quinoline was mainly oxidized into carbon dioxide and small amount of carbon monoxide. Nitrogen atom of quimoline was mainly transformed into ammonia, nitrogen and little amount of N-containing compounds. It was found that increasing the temperature was benefit for the generation of gas and ammonia. Pressure had little effect on the content of products. The increase of the residence time and the excess oxidation could benefit the conversion of carbon monoxide into carbon dioxide. Quinoline oxidation in supercritical water was investigated over the temperature range of 440~460℃ and the pressure range of 25~27MPa, with the residence time of 60~80s and excess oxidation ratio of 2~3. At these conditions, 70~80% of carbon were oxidized into carbon dioxide, while 10~15% of carbon was oxidized into carbon monoxide. 25~30% of nitrogen was converted into ammonia and 55~60% of nitrogen was changed into nitrogen. The TOC removal was between 94% and 98%.