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在众多的污水处理方法中,活性污泥法受到人们的广泛关注,活性污泥法作为重要的处理污水方法之一,具有很多优势. 但是随着国内外对污水治理的日益重视和城市污水处理厂的不断建设,大量的剩余污泥作为活性污泥法处理污水的副产物排出[1]. 污泥因其含水率高、含有大量病原体和微生物等有害生物、重金属及有机物含量高等特点,容易对环境造成二次污染[2],污泥的有效处理处置是亟待解决的重要问题. 污泥脱水是常规的污泥处理方法,在污泥脱水之前需要经过一定的调理使其满足后续脱水要求,所以,选择合适的污泥调理方法对改善污泥脱水性能尤为重要.
过氧化钙(CaO2)作为一种热稳定性好的环境友好型材料,被广泛应用于农业种植、水产养殖、食品保存、医疗以及环境领域[3]. CaO2具有高能的过氧化物共价键,当CaO2与水接触时,能够缓慢释放过氧化氢(H2O2),同时还会生成羟基自由基、过氧化氢自由基等具有强氧化性的自由基(反应式见式(1—5))[4]. 近年来,因其具有稳定的氧化性,CaO2在污泥处理方面的应用成为一个新的研究热点. Wang 等研究发现,通过CaO2预处理污泥后,难降解有机物可以转化为可生物降解,促进污泥中可生物降解基质的水解和分解代谢,进而增强污泥厌氧消化效果[5]. 有研究表明,CaO2可以破解污泥EPS结构,释放污泥中的束缚水[6]. Wang等的研究表明,通过联合CaO2和微波预处理污泥,预处理后污泥的CST值相较于原泥下降52% [7]. 通过热处理与CaO2联合调理,可以提升污泥脱水性能[8].
除了直接使用CaO2对目标物进行氧化,对CaO2进行活化也是一种常用的技术[8]. 有研究认为,通过微波活化CaO2,能促进CaO2产生更多的HO·和·O2-[7]. 通过过渡金属(Fe2+/Fe3+和Ag+)活化CaO2分解是常用的活化方法[9]. 利用Fe2+活化CaO2可以形成类芬顿反应,但如果不进行pH调节, Fe2+易于被氧化成Fe3+,限制了芬顿反应的效率. 有研究指出,利用含铁矿物对H2O2进行活化可以克服这一缺陷[10]. 黄铁矿(FeS2)是一种常见的脉石矿物,与矿床中的有价矿物伴生,可通过常规浮选方法轻松处理[11]. 最近有研究发现,利用黄铁矿活化CaO2降解磺胺,相比常规的芬顿反应,磺胺的氧化效率从30%提升至80%,(主要反应见式(6—9))[12]. Zhou等研究表明利用黄铁矿活化CaO2处理邻苯二甲酸二乙酯(DEP),78%的DEP在24 h内被降解[13]. 这些结果说明,通过黄铁矿活化CaO2能有效促进HO·产生,但目前尚未发现关于利用黄铁矿活化过氧化钙调理污泥的研究,其对污泥脱水性能的影响及机理尚未清晰,因此本研究利用黄铁矿-CaO2作为一种新型的芬顿法对污泥进行调理,以期达到破解EPS从而释放结合水的效果,并通过EPS性质及污泥絮体性质变化探究其对污泥脱水性能的影响机理.
本研究对不同污泥样品进行EPS的提取,并对提取出来的EPS样品进行含量测定、三维荧光光谱检测,以表征调理前后污泥EPS性质变化. 同时对不同污泥样品的粒径分布进行检测,探究调理方法对污泥絮体团聚性能变化的影响.
黄铁矿活化过氧化钙(CaO2)调理提升污泥脱水性能
Improving sludge dewatering performance by conditioning of activated calcium peroxide (CaO2) with pyrite
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摘要: 本研究提出了一种利用黄铁矿活化过氧化钙(CaO2)的污泥调理技术,考察了黄铁矿和CaO2单独/复合调理污泥对污泥脱水性能的影响. 本研究中结合胞外聚合物(EPS)性质变化(各层EPS含量、三维荧光光谱)以及污泥絮体结构变化(污泥絮体粒径)分析不同调理方法对污泥性质的影响. 结果表明,在黄铁矿和CaO2投加量分别为1 g·L−1和30 mg·g−1 TS调理条件下,污泥样品有最低的SCST值(0.55). 在研究中发现,通过破解EPS结构虽然能提升污泥脱水性能,但过度的EPS结构破解,会导致大量污泥内部有机物释放,絮体粒径大幅下降,反而降低污泥的脱水性能.Abstract: In this study, a sludge conditioning technology using pyrite activated calcium peroxide (CaO2) was proposed to improve sludge dewaterability, and the effect of pyrite and CaO2 alone/combined conditioning sludge on sludge dewatering performance was investigated. The effects of different conditioning methods on the properties of sludge were analyzed by combining the changes of extracellular polymeric substance (EPS) properties (EPS content and Three-Dimention fluorescence spectrum of each layer) and the structural changes of sludge floc (particle size of sludge floc). The results showed that the sludge samples had a lowest SCST value (0.55) when the dosage of pyrite and CaO2 was 1 g·L−1 and 30 mg·g−1TS, respectively. It was found that cracking EPS structure can improve the sludge dewatering performance, however, excessive decomposing EPS structure will lead to the release of a large number of organic compounds into the sludge and the particle size of flocs will decrease significantly, resulting in the poor sludge dewatering performance.
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Key words:
- pyrite /
- calcium peroxide /
- sludge dewatering.
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