【作者】 王齐；

【导师】 吕永康；

【作者基本信息】 太原理工大学 ， 化学工程与技术， 2013， 博士

【摘要】 印染废水水量大、化学需氧量(COD)高、色度高、成分复杂多变且含有有毒有害成分,是难处理的工业废水之一,采用传统的处理方法在COD去除和脱色上存在一定难度。超临界水氧化(SCWO)技术处理有机废弃物,反应速度快、污染物降解率高,氧化产物对环境无污染,处理后的废水可达标排放或者回用。本文采用超临界水氧化技术处理工业印染废水,考察了超临界水氧化及热解过程中反应条件的变化对废水中总有机碳(TOC)和氨氮去除效果的影响,在实验的基础上,建立了以污染物TOC为特征参数的氧化和热解过程动力学方程,此外,以废水中总溶解固体(TDS)为特征参数,利用自建的盐分离器考察了SCWO反应同时盐分离器的操作参数对废水中无机盐(TDS)脱除效率的影响,探讨了过程出水回用于漂洗或者印染工艺的可能性,简单计算了过程的运行成本,探讨了该技术工业化应用的前景。通过以上考察主要得出结论如下：1.在印染废水的SCWO过程中,温度对废水中TOC和氨氮降解的影响最为显著,且温度和停留时间的改变对过氧比较小的反应影响更大。氨氮在低温下很难降解,只有在较高的反应温度下,经SCWO过程氨氮才能降解。2.在废水的超临界水(SCW)热降解过程中,温度同样是对TOC降解最重要的影响因素,停留时间对TOC热解效率的影响同样显著,而热解过程没有发现氨氮降解。3.将废水超临界水氧化与热解的降解效果进行对比可知,温度变化对热解过程TOC降解效率影响更大,且在较低反应温度下加入氧化剂对降解作用更明显,而氨氮在较低温度或者没有氧化剂的条件下几乎不降解,在同样的较低温下延长停留时间对氨氮降解也没有帮助。4.采用准一级动力学法建立了废水SCW热解过程的TOC降解动力学方程,采用多元非线性回归法建立了当氧化剂大量过量时废水SCWO过程的TOC降解动力学方程,在此基础上,采用龙格库塔法建立了当氧化剂按照化学计量加入时的废水SCWO过程TOC降解动力学方程,目的是考察反应过程氧化剂浓度变化对反应速度的影响。具体表达式如下：热解(准一级动力学法)：氧化(多元非线性回归法)：氧化(龙格库塔法)：5.在废水脱盐过程中,温度对除盐效率的影响同样最为显著。实验条件下,在盐分离器最短停留时间50.76s内,废水超临界脱盐过程或许已经完成,停留时间的延长对脱盐率没有影响。在一定温度下,废水脱盐后出水盐含量(TDS)受到原水盐浓度变化的影响。6.本废水经SCWO处理后出水能够达到国家一级排放标准且可回用于漂洗过程,而用于印染过程指标尚不能满足。7.经过简单计算,采用SCWO法处理COD为3000mg/L的印染废水,以纯氧为氧化剂,运行成本约为20.25元/m3。8. SCWO技术末来具有广阔的工业应用前景,但是在待处理原料的选择,反应器设计、工艺条件的优化,反应释放能量的有效利用等方面还需进行深入研究,才能够克服盐沉积、避免材料腐蚀、节省运行费用等,使得该技术真正引起大众关注。更多还原

【Abstract】 Dyeing wastewater is one kind of refractory industrial wastewater. Because of the characteristics of the wastewater such as large water volume, high concentration of organic pollutant, deep chromaticity, high alkalinity, changeable water quality and complex ingredient, it is difficult to remove organic substances and colority from the wastewater completely by conventional means.Supercritical water oxidation(SCWO) is a new and effective technology for treatment of organic waste. This technology has the advantages of high organics destruction efficiency, short reaction time and friendly environment, the effluent after treatment can discharge or reuse since it could meet the national discharge standard. In this dissertation, the dyeing wastewater obtained from a printing and dyeing mill was treated by SCWO. The effect of reaction conditions on the degradation of total organic carbon(TOC) and ammonia nitrogen was investigated in the SCW oxidation and pyrolysis processes. Based on the experiments, the kinetic equations for TOC degradation efficiency about the oxidation and pyrolysis processes in SCW were established. Besides, the effect of operation parameters of the self-built salt separator in which salts in the wastewater were removed on total dissolved solids(TDS) removal efficiency were discussed. The possibility of effluent reuse after SCWO treatment was studied and the operation cost of SCWO process was calculated simply. The application of SCWO technology in industry was discussed too. Through above analysis, the main conclusions are as follows:1. The effect of temperature on TOC and ammonia removal from the wastewater in SCWO process is the most remarkable. The changes of temperature and residence time have greater effect on the TOC degradation of smaller excess oxygen reaction. The degradation of ammonia nitrogen is difficult at low temperatures, it can be degraded only at high temperatures in SCWO process.2. For the SCW pyrolysis, temperature is the most important influence factor in TOC degradation too and the effect of the residence time can not be ignored, but degradation of ammonia nitrogen is not be found in this process.3. It can be seen from the comparison pyrolysis with oxidation reactions in SCW, the changes of temperature have greater influence on TOC pyrolysis and the influence of oxidant on TOC conversion is obvious at a lower temperature, but degradation of ammonia nitrogen may remain unaffected by the extension of residence time and adding oxidant in the lower temperature.4. A kinetic equation based on TOC removal of SCW pyrolysis was established by pseudo-first order kinetics. Another kinetic equation for TOC removal of SCWO was built up by multiple nonlinear regression when excess oxidant was added. Based on the above results, the third kinetic equation for TOC removal of SCWO was set up by using Runge-Kutta algorithm at the condition with stoichiometric oxygen supply to explore the influence of oxidant concentration on TOC conversion. Their expressions were given as follow: SCW pyrolysis (pseudo-first order kinetics): SCWO (multiple nonlinear regression): SCWO(Runge-Kutta algorithm):5. For the desalination process in salt separator, temperature has the most significant effects on the desalination efficiency. The process of desalination of the wastewater in supercriticality may be completed in50.76s. Under a certain temperature, the content of TDS in effluent after desalination is affected by the initial salt(TDS) concentration of the wastewater.6. The wastewater treated by SCWO can meet the national emission standard and be used for rinsing processes, but it can not be used in dyeing and printing process.7. After a simple calculation, the operating cost using SCWO for treating the dyeing wastewater is about20.25yuan/m3when CODCr of the wastewater is3000mg/L and hydrogen peroxide is used as oxidant.8. SCWO technology will have a broad prospect in industrial application in the future, but some respects such as the choice of raw material, design of reactor, optimization of process conditions and utilization of reaction releases energy should be studied deeply, so we will be able to overcome the salt deposition, avoid the material corrosion, save operating cost. The SCWO technology will eventually be accepted.更多还原