连续型超临界水氧化系统出水酸碱性分流试验研究  

Experiment for separating the effluent water with different acidic and alkaline mixtures in continuous supercritical water oxidation system

作　　者：赵光明[1] 刘玉存[1] 柴涛[1] 王洪伟[1] 田江霞 

机构地区：[1]中北大学化工与环境学院,太原030051 [2]山西天和高清科技有限公司,太原030051

出　　处：《安全与环境学报》2016年第4期297-301,共5页Journal of Safety and Environment

摘　　要：在用连续型超临界水氧化设备处理废水时,经常发现系统的净化出水pH值变小、排盐出水pH值变大。为了深入研究并揭示其机理,选择原碱性废水中和水、原酸性废水中和水、弱碱性废水、NaCl水溶液、纯自来水和纯NaOH水溶液6种典型水样进行定量试验。结果表明,连续型超临界水氧化系统存在净化出水和排盐出水pH值变化的现象,即使废水在进入系统前调整为中性(pH=7),反应后依然是净化出水pH<7,排盐出水pH>7。该现象很可能是由于在超临界状态下原水中无机酸根离子和金属阳离子的结晶盐离解生成了H^+、OH^-,随后各自缔合成酸性和碱性物质。缔合的酸性物质留在超临界水中,并随之从净化水出口排出,降低了出水的pH值;缔合的碱性物质混入盐结晶析出物中,随之在亚临界区溶解并经过排盐口流出,而重新溶解的金属氢氧化物增加了排水的pH值。另外,在超临界水氧化反应器复杂的氧化腐蚀环境下也生成了一定量的OH^-和酸缔合物,它们对改变出水pH值有一定作用。酸根离子极难从超临界水氧化系统中分离,因此对碱性废水要慎重中和,特别要慎重选择酸根离子,最好不要用盐酸中和,这是因为其带入的Cl^-会引起超临界系统内的氯腐和系统净化出水口的酸腐。研究表明,因为存在出水pH值的变化,对超临界水氧化系统出水的纯净程度必须予以重新考虑。In order to disclose the mechanism of pH value of purified water being decreased and that of salt-discharged water being increased when treating wastewater by using continuous supercritical water oxidation equipment,we have chosen to use six typical water samples in the quantitative experiment. The said six typical water samples are neutralized alkaline wastewater,neutralized acid wastewater,weak alkaline wastewater,NaC l aqueous solution, pure water and pure NaOH solution, respectively.When treating the sampling wastewater,we have adopted a kind of experimental facility known as the continuous supercritical water oxidation unit. With the experiment going on,it is possible to find that pH values of the purified water and salt-discharged waterhave been changed. Even if the wastewater is adjusted to be neutral（ pH = 7） before being transferred into the system,pH〉7could been found for the purified water and pH〈7 could been observed for the salt-discharged water. What is more,the above mentioned phenomenon can be attributed to the crystallization salt being composed in some compound with inorganic acid ions and metal cations in the waste water when dissociated into H＋and OH-,and then associated with other ions to form the acid and alkaline substances under the supercritical conditions. And,as a result of combination,the associated acids tend to remain in the supercritical water and discharged from the purified water outlet,thus reducing pH value of the effluent water. On the contrary,the associated basic substances can also be mixed into the crystallized salt and re-dissolved in the subcritical zone,then discharged from the salt-discharged outlet,thus increasing pH value of the effluent water. What is more,there would appear a tendency of certain amounts of OH-and acid-associations being generated in the oxidation and corrosion environment of the supercritical water oxidation reactor,which plays a certain role in changing pH value of the effluent water. Thus,the results show that it is difficult to separate

关 键 词：环境工程学 超临界水氧化 废水处理 PH值变化 系统出水 

分 类 号：C703.1[社会学]