化工废水处理污泥中有机污染物累积与分布特征

发布时间：2018-01-08 18:12

本文关键词：化工废水处理污泥中有机污染物累积与分布特征　出处：《河北工程大学》2015年硕士论文　论文类型：学位论文

【摘要】：化工废水处理污泥含有大量废水中迁移转化而来的毒性污染物,尤其是毒性有机污染物,由于并未得到有效消减,这部分污染物在环境中的危害持续存在,虽然近些年来在化工废水产生量和废水处理率持续增加的背景下,化工废水处理污泥的环境风险开始得到重视,但也主要集中在重金属引起的环境毒性方面,对浓度相对较低但毒性更强的有机污染物尚停留在污染水平调查阶段,而对其从废水进入污泥的累积过程和迁移规律认识不足,为污泥的管理属性认定和处置利用带来了困难。因此有必要对化工废水污泥中有机污染物从水相向泥相迁移转化的富集机制、影响因素及其在污泥中的分布特征、污泥吸附的归趋贡献等加以研究。本论文选取煤液化、PTA及己内酰胺三类化工废水及其处理污泥为研究对象,结合定性分析和污染物毒性特征,筛选出VOCs、PAHs以及苯酚为后续研究的特征污染物,对其在废水处理过程中的污染水平、去除特征及其在污泥中的富集浓度进行分析,并在此基础上对其水泥相迁移转化规律、污泥吸附的归趋贡献和去除规律以及其在生化污泥各组分中的空间分布特征进行了初步探究。三类化工废水及其污泥中VOCs均主要以苯系物为主,PAHs则主要以低分子量的萘、菲等单体为主,二者污泥富集倍数可高达几百至上千倍,危害性明显,对于各处理工艺其ΣVOCs水相去除率均不足40%,去除效果有限,且在一定程度上促进了部分毒性污染物如氯代烃的产生;低分子量PAHs水相去除率相对较高,均大于70%,而随着环数和分子量的增加其降解难度有所提高;苯酚在煤液化废水入水中浓度较高,虽易消减且水相去除较为彻底,但其在污泥中的高度富集增加了环境风险。三类化工废水处理产出的污泥中,生化污泥对VOCs(尤其是苯系物)和PAHs的吸附能力强于无机污泥;好氧污泥吸附VOCs的能力强于厌氧污泥,但其吸附PAHs的能力反不及后者;混合污泥吸附PAHs的能力有所增强,甚至超出单纯生化污泥的吸附量;污泥对苯酚的吸附仅与产泥工序的先后有关,而与污泥理化性质关系不大。煤液化废水归趋分析中ΣVOCs的主要归趋途径为随水排出(60.33%),挥发和生物降解贡献率不足17%,污泥吸附虽不占主导作用(22.95%),但归趋贡献率远高于早前报道;Σ16PAHs的主要归趋途径为污泥吸附(51.90%),其次为随水排出(22.17%)和化学氧化降解(17.41%);苯酚主要为化学氧化降解(95.31%),其次为挥发及生物降解(4.59%),出水和污泥吸附所占比例虽小,但进水苯酚总量巨大,使苯酚在污泥中的吸附量同样不容忽视,因此需对污泥中富集的上述有机污染物加强管控;Kow与各归趋途径去除率关系方面,随着Kow的增大,VOCs和PAHs单体的出水排放率逐渐降低,但吸附去除率逐步增大,并在log Kow达到4.5时成为VOCs的主要去除途径,而PAHs归趋中吸附去除始终占主导。不同特征污染物及产泥工艺中泥-水相分配系数Kd差异较大,但基本表现为PAHs稍高于VOCs,而生化污泥则又高于无机污泥,PAHs更易从水相中进入泥相并富集;影响水-泥相分配的因素则主要有污泥理化性质和污染物物化特性两种,在吸附质一致的情况下污泥的有机碳含量(Foc)及比表面积越大,其吸附能力越强,而在吸附剂相对稳定时,污泥更倾向于吸附辛醇-水分配系数(Kow)大的污染物。三类废水处理产生的生化污泥中富集的PAHs和VOCs均主要分布于胞内,且其对VOCs的吸附更占优势,但单就PAHs而言,好氧污泥胞内物对其吸附能力又稍强于厌氧污泥;EPS对PAHs的相对吸附量虽不占优势,但其在初期吸附过程中的作用不可忽视,且不同理化性质的生化污泥中SEPS和BEPS的表现也不一致,其中煤液化3T混合污泥和PTA射流曝气污泥中SEPS吸附PAHs的能力强于BEPS,厌氧污泥中却相反,而微孔曝气池污泥中二者对PAHs的吸附能力则相当;苯酚由于溶解度较大,主要分布于SEPS和胞内,而在BEPS中则难以附着;对比相关研究还发现,随着时间的延长,生化污泥中污染物有从外层EPS向胞内转移的趋势。此外,结合特征污染物的浓度分布和累积特征,三类污泥的处理处置应以焚烧为主,而不宜进行填埋及作为土地利用。
[Abstract]:Chemical wastewater treatment sludge containing toxic pollutants and migration and transformation in a large number of wastewater, especially toxic organic pollutants, because has not been effectively reduced, the harm of pollutants in the environment continue to exist, although in recent years in chemical wastewater and wastewater treatment rate continued to increase under the background of environmental risk of chemical wastewater treatment sludge to get attention, but also focus on environmental toxicity caused by heavy metals, the relatively low concentration of organic pollutants but still more toxic pollution levels in the investigation stage, and the process of accumulation and migration from the wastewater into the sludge of lack of knowledge, for the management of the identification and disposal of the sludge properties is difficult. It is necessary for the enrichment mechanism of organic pollutants in water from chemical wastewater sludge to sludge phase transformation, and its influencing factors in sludge The distribution characteristics of the sludge adsorption attribution contribution to research. This paper selects the coal liquefaction, PTA and caprolactam three kinds of chemical wastewater and treatment of sludge as the research object, combining the qualitative analysis and the toxicity of pollutants characteristics, selected VOCs, PAHs and phenol as the characteristic pollutants of follow-up study, the wastewater treatment process the level of pollution removal characteristics and in sludge concentration enrichment analysis, and on the basis of the phase transformation regularity of cement, and removal of sludge adsorption tendency and its contribution in biochemical sludge in different components of the spatial distribution characteristics of a preliminary inquiry. Three kinds of chemical wastewater treatment and sludge in VOCs major in benzene, PAHs is mainly in the low molecular weight of naphthalene, phenanthrene and other monomers, the two sludge enrichment multiples can be as high as hundreds of thousands of times, obvious dangers, for each treatment process The total VOCs removal rate of water was less than 40%, the removal effect is limited, and to a certain extent, promotes the part of the toxic pollutants such as chlorinated hydrocarbons; low molecular weight PAHs water removal rate is relatively high, are more than 70%, and with the ring number and the increase of the molecular weight of the degradation has increased the difficulty of phenol concentration in water; high in coal liquefaction wastewater, and the removal of water is easy to cut more thoroughly, but the height of the sludge in the enrichment of increased environmental risks. Three kinds of chemical wastewater treatment sewage sludge, biochemical sludge on VOCs (especially benzene) and PAHs adsorption ability to the inorganic sludge; sludge aerobic ability the adsorption of VOCs is stronger than that of anaerobic sludge, but the adsorption capacity of PAHs than the latter; the ability of mixed sludge adsorption of PAHs was enhanced, and even beyond the adsorption of pure biochemical sludge; sludge adsorption of phenol and the only chronological about Mason But, with the physicochemical properties of sludge had little relation to the main tendency of coal liquefaction wastewater of sigma VOCs chemotaxis pathway for discharge with water (60.33%), volatilization and biodegradation contribution rate of less than 17%, the sludge adsorption although not dominant (22.95%), but the fate of the contribution rate is much higher than previously reported mainly; to the trend of sigma 16PAHs approach for sludge adsorption (51.90%), followed by discharge with water (22.17%) and (17.41%) chemical oxidation degradation; phenol was mainly chemical oxidation degradation (95.31%), followed by volatilization and biodegradation (4.59%), the effluent and sludge adsorption proportion is small, but the huge amount of phenol. The adsorption amount of phenol in the sludge can not be ignored, therefore the need to strengthen the control of the organic pollutants in sewage sludge; Kow and the fate of the way of removal rate, with the increase of Kow, VOCs and PAHs monomer water discharge rate decreased gradually, but the adsorption rate gradually Step increases, and in the log of Kow 4.5 has become the main removal pathway of VOCs, and PAHs to the removal of the leading trend. The different characteristics of pollutants and sludge production in the process of mud - water partition coefficient Kd is different, but the basic performance of PAHs was slightly higher than that of VOCs, but also higher than the inorganic sludge sludge. PAHs more easily from the aqueous phase into the mud and water sediment enrichment; factors affecting the phase distribution is mainly sludge physicochemical properties and physicochemical properties of two kinds of pollutants, the organic carbon content in sludge adsorption consistent condition (Foc) and the specific surface area is larger, the adsorption capacity is strong, and the adsorbent is relatively stable, the sludge adsorption tends to octanol water partition coefficient (Kow) of pollutants. Three kinds of wastewater treatment by biochemical sludge enriched in PAHs and VOCs were mainly distributed in the cytoplasm, and the adsorption of VOCs is more dominant, but the single PAHs, aerobic Sludge intracellular extracts on the adsorption capacity of the anaerobic sludge is stronger than EPS; on PAHs relative adsorption is not dominant, but the beginning of the adsorption process can not be ignored, SEPS and BEPS and the biochemical sludge physical and chemical properties of the performance is not consistent, including coal liquefaction 3T SEPS mixed adsorption PAHs sludge and PTA jet aeration in sludge anaerobic sludge is stronger than BEPS, but on the contrary, the adsorption capacity of two sludge micropore aeration tank of PAHs is quite large; because of the solubility of phenol, mainly distributed in SEPS and intracellular, and is hard to adhere to the BEPS; comparing the related research also found that with the extension of time, the pollutants are transferred from the biochemical sludge in the outer EPS to intracellular trend. In addition, combined with the characteristics of pollutants concentration distribution and accumulation characteristics, three kinds of sludge disposal should be burning, rather than as a landfill and land Make use of.

【学位授予单位】：河北工程大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X78

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