Efficient treatment and energy recovery for supercritical water oxidation of wastes

超临界水氧化技术是一种将有机物氧化为二氧化碳、水和氮气的环保技术。采用超临界水氧化法处理城市剩余污泥和糖蜜酒精废水。反应在间歇反应器或流动反应器中进行，以过氧化氢为氧化剂，反应温度为473 K ~ 873 K，液相产物无色无味。反应产物的总有机碳（TOG），有机酸，铵离子进行了分析。TOG随温度和氧化剂用量的增加而降低。乙酸和氨被检测为产品中的主要难降解中间体。当氧化剂用量超过化学计量要求时，液相中的有机碳几乎被完全破坏。完全破坏反应中产生的氨需要比乙酸更高的温度。建造了1/8英寸-1.7米的管式流动反应器，用于连续处理废物。流动反应器对污泥进行了有效的降解。测量总有机碳作为反应时间的函数。采用单一一级反应动力学模型和两个包括乙酸等难降解中间体的通用模型对反应动力学数据进行了分析。一级反应模型的速率常数与文献报道的一致。在广义模型中，难降解中间体的分解反应速率常数与乙酸的分解速率相当。

Supercritical water oxidation has been focused as an environmentally attractive technology where organic materials are oxidized to carbon dioxide, water, and N_2. We have applied the supercritical water oxidation to municipal excess sludge and alcohol distillery wastewater of molasses. The reaction was carried out in a batch reactor or a flow reactor with hydrogen peroxide as an oxidant in the temperature range of 473K-873K.The liquid phase products were colorless and odorless. The reaction products were analyzed in terms of total organic carbon (TOG), organic acids, and ammonium ion. TOG decreased with temperature and the oxidant amount. Acetic acid and ammonia were detected as major refractory intermediates in the product. When more than stoichiometric demand of oxidant was used, organic carbon in liquid phase was almost completely destroyed. Complete destruction of ammonia produced in the reaction required higher temperature than that of acetic acid. A tube-type flow reactor (1/8 inch-l.7 m) was constructed for the continuous treatment of wastes. The sludge was efficiently destructed by the flow reactor. Total organic carbon was measured as a function of reaction time. The kinetic data were analyzed by a single first order reaction model and two generalized models including refractory intermediate such as acetic acid. The rate constant in first order reaction model coincides with those reported in literature. The reaction rate constant for the decomposition of refractory intermediate in the generalized model was comparable to decomposition rate of acetic acid.