超临界水氧化去除污泥中化学需氧量的动力学

Kinetics of removal of chemical oxygen demand in municipal sewage sludge by supercritical water oxidation

以生活污水厂的生物污泥为研究对象,采用间歇式反应装置,通过超临界水氧化法处理生物污泥,建立处理过程中的化学需氧量（chemical oxygen demand,COD）去除动力学模型.实验考察反应温度、反应压力、停留时间及氧化剂含量等条件对生物污泥COD去除率的影响.研究表明,在反应温度为400-440℃、反应压力为29 MPa、停留时间为300 s、氧化剂过氧比为300%的反应条件下,生物污泥的COD去除率可达90%以上.通过超临界水氧化处理后的出水COD与反应条件之间的关系,建立了超临界水氧化法处理生物污泥过程中COD去除率的反应动力学模型,得到在26 MPa时,反应活化能为89.3 k J/mol、指前因子为2.84,该理论计算值与实验值对比偏差在±6%范围内,说明所建模型可较好地预测不同反应条件对COD去除率的影响.

Sewage sludge from municipal waste water treatment plant was treated by supercritical water oxidation with batch reactor, and then dynamical model of effluent chemical oxygen demand （COD） removal in the sewage sludge is built. The effects of reaction temperature, reaction pressure, retention time and oxidant dosage rate on effluent COD removal in the sewage sludge are systematically investigated. The results show that effluent COD removal rate in the sewage sludge by supercritical water oxidation can reach above 90% under the conditions of reaction temperature of 400-440 ℃, reaction pressure of 29 MPa, retention time of 300 s and oxidant dosage rate of 300%. The relations between the reaction conditions and effluent COD are further studied to build kinetics model of effluent COD removal by supercritical water oxidation, where the reaction activation energy and pre-exponential factors are 89. 3 kJ/mol and 2.84, respectively. The deviation between the calculated value and the experiment value of the model is controlled within ± 6%, which indicates the model can precisely predict the influence of the different conditions on the effluent COD removal rate in the sewage sludge by supercritical water oxidation.