【作者】 孙伟华；

【导师】 陈吕军；

【作者基本信息】 清华大学 ， 环境科学与工程， 2013， 博士

【摘要】 印染废水种类繁多，但多属有机废水，常用以生物为核心的工艺处理。聚乙烯醇（PVA）和偶氮染料是印染废水中典型难降解有机污染物，对生物工艺造成了很大冲击。本研究旨在将电离辐射技术（IR）应用为难降解有机印染废水的预处理技术，以提高其可生化性，并探索IR与生物工艺耦合的可行性。应用放射源钴-60产生的γ射线辐照PVA水溶液的研究表明，在本研究条件下，PVA水溶液的可生化性随吸收剂量的增加而升高。PVA330mg/L的中性溶液接受9kGy辐照后与活性污泥混合液的比耗氧吸收速率（SOUR）在反应0.5h时被提高了34%。另外，PVA的去除是辐照降解和辐照聚合共同作用的结果。中性条件下，PVA浓度较低时，如330mg/L，以羟基自由基（OH）和氢原子（H）的辐照降解作用为主；PVA浓度较高时，如3000mg/L，以OH的辐照聚合/交联作用为主，且酸性环境利于PVA辐照聚合的发生。γ辐照偶氮染料茜素黄-GG（AY-GG）水溶液的研究表明，IR对改善其可生化性和急性生物毒性的效果明显。100mg/L AY-GG水溶液在接受辐照初期（<1kGy）会产生对好氧微生物有抑制作用的中间产物，水溶液的SOUR曲线明显下降。随辐照继续（>1kGy），其SOUR曲线逐步升高。9kGy时，水溶液的发光细菌急性生物毒性也明显降低。另外，γ辐照含AY-GG和PVA的模拟印染废水的研究表明，IR对改善该废水的可生化性和急性生物毒性都有明显效果，且在辐照初期同样发现了对微生物产生抑制的中间产物，并随继续辐照而被消除。应用电子加速器产生的电子束辐照处理实际印染废水研究表明，可生化性差（BOD5/COD <0.3）的废水适合IR-生物工艺处理。为此，本研究选择含PVA印染废水（BOD5/COD <0.1）进行电子束辐照—膜生物反应器（MBR）耦合工艺处理。结果表明，IR预处理缓解了PVA（Mw：74800~79200）对超滤膜（孔径0.02μm）的堵塞，成功实现了含高分子PVA印染废水的IR-MBR耦合处理。此外，IR联合臭氧（O3）处理PVA水溶液和AY-GG水溶液时，均发现“协同效应”。该效应不仅表现在IR与O3同时作用下对OH产额的协同增加上，还表现在先进行O3氧化、再进行IR处理的组合方式对水中有机物的协同去除上。更多还原

【Abstract】 Dyeing wastewaters are extremely complicated. However, most of the wastewatersare organic wastewater, whose core treatment process is based on generally biologicaltechnology. As typical refractory organic pollutants in dyeing wastewater, polyvinylalcohol (PVA) and azo dyes have made a serious problem on biological process. Thepurpose of this study is to enhance biodegradability of refractory organic dyeingwastewaters and to remove refractory organic pollutants in these wastewaters by usingionzing radiation (IR) as a pretreatment, then to explore the possibility of refractoryorganic dyeing wastewater treatment by using IR coupling with biological process.Ionizing radiation-induced removal of PVA was investigated in aqueoussolution under γ-irradiation using a60Cobalt source. The results showed that thebiodegradability of PVA-containing wastewater with low initial concentration(e.g.,330mg/L) could be improved greatly with increasing irradiation dose.Specific oxygen uptake rate (SOUR, mg O2· g MLVSS-1· h-1) of activatedsludge using the9kGy irradiated PVA solutions was enhanced34%at0.5h.Under γ-irradiation, PVA removal pathway was found to be affected bydecomposition and polymerization. The decomposition effect dominated thePVA removal process at low PVA concentration, i.e.,330mg/L under neutralcondition. Hydroxyl radicals (OH) and hydrogen atoms were found to be thekey radicals in PVA decomposition. Oppositely, the polymerization/crosslinkingeffect dominated the PVA removal process at high PVA concentration, i.e.,3000mg/L under neutral condition. Also, OH radicals were found to be the keyradicals in PVA polymerization/crosslinking. Furthermore, acidic condition wasmore benefit for PVA polymerization under γ-irradiation.Ionizing radiation-induced degradation of an azo dye-Alizarin yellow-GG(AY-GG) was investigated in aqueous solution under γ-irradiation. The results showedthat IR had a good performance on biodegradability enhancement and acute toxitiydelimination of the azo dye wastewater. However, the SOUR curve appeared todecrease at early stage of irradiation (<1kGy), indicated that a partial toxicintermediates could generate that inhabited the activities of aerobic microbes. Fortunately, the inhibition was eliminated by further irradiation. The SOUR curvesincreased step by step. Furthermore, the acute toxicity of the solution decreasedobviously at9kGy. In addition, the similar law of biodegradability enhancement andacute toxitiy delimination of a simulated dyeing wastewater containing PVA and AY-GGwere found during γ-irradiation.Ionizing radiation of actual dyeing wastewaters was investigated byelectron beam (EB) irradiation using an electron accelerator. The results showedthat dyeing wastewaters with poor biodegdability (BOD5/COD <0.3) were suitfor IR-biological treatment. Thus, PVA contained dyeing wastewater(BOD5/COD <0.1) was studied by using IR-membrane bioreactor (MBR)coupling treatment. The results indicated that IR pretreatment slowed down themembrane (0.02μm) fouling by PVA (Mw:74800~79200). Finally, the researchachived the goal that using IR-MBR coupling process as the PVA containeddyeing wastewater treatment.In addition, synergistic effect was found during the treatment of PVA orAY-GG aqueous solutions between IR and ozone (O3) oxidation. Importantly,the synergistic effect not only appeared to enhance OH yeild during the IR andO3oxidation at the same time, but also appeared to remove the total organiccarbon of wastewaters by the sequential order of O3oxidation followed by IR.更多还原