臭氧氧化处理染料废水的过程强化

发布时间：2018-08-28 12:22

【摘要】：染料废水存在水量大、水质复杂、色度深、以及含有“三致”毒性物质等特点。若不妥当处理,将造成严重的环境污染,从而危害人体健康。在染料废水处理方面,臭氧氧化技术由于其高效性和无二次污染特点而被广泛研究。然而,传统的臭氧氧化技术由于其成本较高,传质效率低,臭氧利用率低,从而阻碍了该技术工业应用发展。本研究设计微泡加压反应器强化臭氧氧化技术,氧化降解酸性红18(AR 18)模拟染料废水。采用VOF模型模拟外加压力场对微泡反应器内气液界面的变化规律,并考察了该反应器对臭氧传质,废水脱色及矿化(TOC去除率)效率的影响。同时还将微泡加压强化O_3/Ca(OH)_2体系,研究了该联用技术对染料废水矿化降解的影响及强化机理。全文的主要研究结果如下:微泡加压反应器有效提高了其传质效率,液相中臭氧浓度达到稳定状态速率较快,其液相中臭氧浓度约为11.7 mg/L,比鼓泡体系高约10%。微泡加压反应器中羟基自由基产生量高于传统鼓泡体系,臭氧通入5 min,微泡体系中羟基自由浓度高达121.45μM,比鼓泡体系提高了约11倍。液相中臭氧浓度以及羟基自由基产生量受压力影响较小,温度影响较大,水中臭氧浓度随温度的增加而减少,羟基自由基产生量随温度增加而增加,两者都随进口臭氧浓度及流量的增加而增加。微泡反应体系中废水脱色及矿化效率都高于鼓泡体系,微泡体系中染料废水完全脱色需8 min,臭氧氧化处理35 min,对废水TOC去除率高达70%以上。矿化过程通过一级动力学拟合,测得微泡体系中一级反应速率常数为0.0343 min-1,比鼓泡体系反应速率常数高一个数量级。在微泡体系中,体系压力变化对废水脱色率及TOC去除率影响较小;在相同处理时间下,酸性红18初始浓度越大,脱色率和矿化率越小;进口臭氧浓度越高,染料废水的脱色及矿化效果越好。运用色谱-质谱联用(GC-MS)检测了氧化过程中8种中间产物,并依此推测出了酸性红18的降解机理。在微泡加压反应器强化O_3/Ca(OH)_2体系中,考察了Ca(OH)_2用量、体系压力、液相温度、酸性红18初始浓度以及进口臭氧流量及臭氧浓度对废水脱色及TOC去除影响。在0~3 g/L间,废水脱色和矿化效率随着Ca(OH)_2加入量的增加而增加,最佳Ca(OH)_2用量为2 g/L。废水脱色率及TOC去除率受体系压力、温度影响较小;在相同处理时间下,酸性红18初始浓度越大,脱色率和矿化率越小;臭氧进口浓度和进口流量的增加有利于酸性红18脱色与矿化。O_3/Ca(OH)_2体系中强化机理为Ca(OH)_2电离产生OH-和Ca~(2+),在OH-/O_3条件下有利于羟基自由基产生,同时Ca~(2+)及时去除羟基自由基清除剂CO_32-生成CaCO_3沉淀,从而使反应能持续高效进行。
[Abstract]:Dyestuff wastewater is characterized by large quantity of water, complex water quality, deep chroma, and containing three toxic substances. If not properly handled, will cause serious environmental pollution, thereby endangering human health. In dye wastewater treatment, ozone oxidation technology has been widely studied because of its high efficiency and no secondary pollution. However, the traditional ozonation technology hinders the development of industrial application because of its high cost, low mass transfer efficiency and low ozone utilization. In this study, a microbubble pressurized reactor was designed to enhance the ozonation process to oxidize and degrade acid red 18 (AR 18) dye wastewater. The VOF model was used to simulate the effect of applied pressure field on the gas-liquid interface in the microbubble reactor, and the effects of the reactor on ozone mass transfer, wastewater decolorization and mineralization (TOC removal efficiency) were investigated. At the same time, the effect of the combined technology on the mineralization and degradation of dye wastewater and its strengthening mechanism were studied. The main results are as follows: the mass transfer efficiency of microbubble pressurized reactor was improved effectively, and the ozone concentration in liquid phase reached stable state faster than that in bubbling system. The ozone concentration in liquid phase was about 11. 7 mg/L, higher than that in bubbling system. The hydroxyl radical production in the microbubble pressurized reactor was higher than that in the traditional bubbling system. The free concentration of hydroxyl radical in the ozone permeated 5 min, microbubble system was up to 121.45 渭 M, which was about 11 times higher than that in the bubbling system. The concentration of ozone and the amount of hydroxyl radical in liquid phase are less affected by pressure, and the effect of temperature is greater. The concentration of ozone in water decreases with the increase of temperature, and the production of hydroxyl radical increases with the increase of temperature. Both increase with the increase of import ozone concentration and flow rate. The decolorization and mineralization efficiency of wastewater in microbubble reaction system is higher than that in bubbling system. The complete decolorization of dye wastewater in microbubble system requires 8 min, ozonation treatment for 35 min, to remove TOC from wastewater up to 70%. The first-order reaction rate constant of 0.0343 min-1, in the microbubble system is one order of magnitude higher than that of the bubbling system. Under the same treatment time, the higher the initial concentration of acid red 18, the smaller the decolorization rate and mineralization rate, the higher the import ozone concentration, the lower the decolorization rate and mineralization rate. The better the decolorization and mineralization of dye wastewater. Eight intermediates in the oxidation process were detected by GC-MS, and the degradation mechanism of acid red 18 was deduced. The effects of the amount of Ca (OH) _ 2, system pressure, temperature of liquid phase, initial concentration of acid red 18, inlet ozone flow rate and ozone concentration on the decolorization and TOC removal of wastewater were investigated in a microbubble pressurized reactor enhanced O_3/Ca (OH) _ 2 system. In the range of 0 g / L, the efficiency of decolorization and mineralization of waste water increases with the increase of Ca (OH) _ 2 addition. The optimal Ca (OH) _ 2 dosage is 2 g / L. The decolorization rate and TOC removal rate of wastewater are less affected by system pressure and temperature, and the higher the initial concentration of acid red 18 is, the smaller the decolorization rate and mineralization rate are under the same treatment time. The increase of ozone inlet concentration and inlet flow rate is beneficial to decolorization and mineralization of acid red 18. O _ (3 / Ca (OH) _ 2) system. The enhancement mechanism is that Ca (OH) _ 2 ionization produces OH- and Ca~ (2), and under OH-/O_3 condition, hydroxyl radical is produced. At the same time, Ca~ (2) removes hydroxyl radical scavenger CO_32- in time to form CaCO_3 precipitate, so that the reaction can be carried on continuously and efficiently.
【学位授予单位】：重庆理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X788

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