The Research On Supercritical Water Oxidation Process For Volatile Phenol Of Coking Wastewater

Phenols are the protoplasm poison, belonging to high toxic substances. According to whether phenols with water vapour can steam out together, they are divided into volatile phenols and not volatile phenols. Volatile phenols as monophenol usually refer to the phenols with boiling point below 230℃. Volatile phenols are toxic, which have serious pollution of water. At present, the traditional wastewater treatment methods, such as physical method, chemical oxidation, biological methods and so on are hard to remove them. Supercritical water oxidation method is a new wastewater treatment technology which can destroy organic pollutants structure thoroughly. It can deal with organic wastewater completely and effectively, so it owe unique advantage than other wastewater treatment technologies. In the paper, we use coking wastewater containing phenols which is difficult to biochemical degrade as the background, and make a comprehensive research to the supercritical water oxidation decomposition of volatile phenol in wastewater. We have obtained some achievements finally. Hoping that this experiment can push the supercritical water oxidation method as a broad application in high concentrations of refractory organic industrial waste water treatment field like coking wastewater.Through consulting a large number of documents and materials, we make fundamental exposition to the sources of coking wastewater, water quality characteristics, harm, processing status and processing methods. Then we introduce the characters of supercritical water, and make a full explanation to the supercritical water oxidation technology. At last we analyse the research situation of wastewater containing phenol.This paper introduces the design, manufacture and system running of the self-built supercritical water oxidation continuous experiment device in detail, and illustrates the test procedure and the experimental condition control specifically. On this basis, the experiment takes the coking wastewater from a coking plant in Taiyuan as the research object, and we do the supercritical water oxidation research of volatile phenol using the successive experiment device.This paper examines the influences of these factors such as reaction temperature, reaction pressure, oxygen excess degree and retention time on the removal rate of volatile phenol in coking wastewater, and as these factors value increases and increases. The influence of reaction temperature on the removal rate is quite obvious, and in the range of investigation, positive effect plays a leading role; because the rise of reaction pressure will has a stricter requirement to the reaction equipment, thus in the actual industrial applications, the reaction pressure is unfavorable and exorbitant; the effects of oxygen excess degree and retention time on the removal efficiency of volatile phenol are very significant, but they have a good value, when more than the value, continue to increase the dosage of oxidant and extend stay time to improve the removal rate are not wise, the trend line slowly tend to be gentle. Based on this, combining orthogonal test results further, we determine the appropriate technological conditions for this experiment:480℃for reaction temperature,28MPa for reaction pressure, oxygen multiples of 2.5, no less than 45 seconds for staying time. In these conditions, the content of volatile hydroxybenzene in the processed wastewater is 0.053mg/L, which reachs level 1 discharging standard of GB 8978-1996.In order to study reaction rule further, deepen the understand of supercritical water oxidation process, this paper also takes GC-MS analysis on the basis of experiment and gets the main middle products of volatile phenol in supercritical water oxidation process. According this, we further speculate out its oxidation degradation pathways.Finally, in order to analyse and evaluate supercritical water oxidation technology comprehensively and systematically, this paper also analyses the technical economy of supercritical water oxidation method on the disposal of organic industrial wastewater from process rationality, treatment effect of the pollutants in wastewater, environmental impact and energy-oriented significance as well as the economy, and further puts forward the countermeasures to improve its economic benefit.