Takahashi Y, Wydeven T, Koo C
Department of Civil Engineering, Niigata University, Japan.
Adv Space Res. 1989;9(8):99-110. doi: 10.1016/0273-1177(89)90033-1.
Controlled-Ecological-Life-Support-System (CELSS) model wastes were wet-oxidized at temperatures from 250 to 500 degrees C, i.e., below and above the critical point of water (374 degrees C and 218 kg/cm2 or 21.4 MPa). A solution of ammonium hydroxide and acetic acid and a slurry of human urine, feces, and wipes were used as model wastes. Almost all of the organic matter in the model wastes was oxidized in the temperature range from 400 to 500 degrees C, i.e., above the critical conditions for water. In contrast, only a small portion of the organic matter was oxidized at subcritical conditions. Although the extent of nitrogen oxidation to nitrous oxide (N2O) and/or nitrogen gas (N2) increased with reaction temperature, most of the nitrogen was retained in solution as ammonia near 400 degrees C. This important finding suggests that most of the nitrogen in the waste feed can be retained in solution as ammonia during oxidation at low supercritical temperatures and be subsequently used as a nitrogen source for plants in a CELSS while at the same time organic matter is almost completely oxidized to carbon dioxide and water. It was also found in this study the Hastelloy C-276 alloy reactor corroded during waste oxidation. The rate of corrosion was lower above than below the critical temperature for water.
受控生态生命支持系统（CELSS）模型废物在250至500摄氏度的温度下进行湿式氧化，即低于和高于水的临界点（374摄氏度和218千克/平方厘米或21.4兆帕）。氢氧化铵和乙酸溶液以及人尿、粪便和擦拭物的浆液用作模型废物。模型废物中几乎所有的有机物在400至500摄氏度的温度范围内被氧化，即高于水的临界条件。相比之下，在亚临界条件下只有一小部分有机物被氧化。尽管氮氧化为一氧化二氮（N2O）和/或氮气（N2）的程度随反应温度的升高而增加，但在接近400摄氏度时，大部分氮以氨的形式保留在溶液中。这一重要发现表明，在低超临界温度下氧化过程中，废物进料中的大部分氮可以以氨的形式保留在溶液中，并随后用作CELSS中植物的氮源，同时有机物几乎完全氧化为二氧化碳和水。在本研究中还发现，哈氏合金C-276合金反应器在废物氧化过程中发生腐蚀。水的临界温度以上的腐蚀速率低于临界温度以下的腐蚀速率。
