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苯酚是重要的有机化工原料,在石油、化工、皮革加工、纺织和制药工业产生的废水中均含有酚类化合物[1-2]。含苯酚废水的处理方法有很多[3-5]。生物法因其处理量大、成本低、二次污染少等优点逐渐成为处理苯酚废水的主要方法[6-8]。生物法主要包括活性污泥法[9]、生物流化床法[10]、固定化细胞法[11]、生物膜法[12-14]等。CHEN等[15]用活性污泥法处理苯酚废水,处理80 d后将进水的苯酚质量浓度提高至350 mg·L−1,此时微生物活性受到抑制,苯酚去除率下降;保持进水苯酚质量浓度不变,在110 d后,活性污泥对苯酚去除率接近于0。LEONG等[16]用序批式反应器(sequencing batch reactor,SBR)处理含苯酚的废水并逐步提高进水苯酚质量浓度,在处理90 d、苯酚质量浓度提高至400 mg·L−1时,污泥活性受苯酚毒性抑制,沉降性能变差。王欢[17]利用填充床电化学生物反应器处理质量浓度为0~250 mg·L−1的苯酚废水,苯酚去除率随其质量浓度的上升而下降,在苯酚质量浓度为250 mg·L−1时去除率为54.59%。上述研究在使用生物膜法和活性污泥法处理苯酚质量浓度逐步递增的废水时,存在苯酚质量浓度提高后微生物活性受到抑制,苯酚去除率下降的问题。
复合式生物膜处理技术兼有生物膜和活性污泥的优点,是污水生物处理中有机物高效消减的主要技术之一,但存在降解速率快时进水苯酚质量浓度低,处理高质量浓度苯酚废水时启动期长的问题。ALVES等[18]用活性污泥-移动床生物膜一体化反应器处理含有高质量浓度苯酚的废水,运行220 d后可以完全处理2 000 mg·L−1的苯酚。ZHUANG等[19]通过投加苯酚降解菌缩短了序批式生物膜反应器(sequencing biofilm batch reactor,SBBR)的启动期,苯酚降解率由75%提高到89%。ISMAIL[20]用SBBR处理苯酚质量浓度为20 mg·L−1的苯酚废水,在150 min时苯酚即可完全降解。YUSOFF等[21]用混合生长序批式反应器(hybrid growth sequencing batch reactor,HG-SBR)处理苯酚质量浓度为200 mg·L−1的苯酚废水,15 min后苯酚质量浓度下降到55 mg·L−1,6 h后苯酚去除率达到98%。
苯酚的生物降解依赖于微生物的功能和活性,微生物特性可以有效地阐明降解机制并影响微生物过程的性能[15]。苯酚毒性会影响活性污泥和生物膜的性能,进而影响苯酚的生物降解,因此,探索在进水苯酚质量浓度提升过程中活性污泥和生物膜性能与苯酚降解的相关性具有重要意义[22-23]。
本研究通过自制的活性污泥-生物膜一体化反应器处理含苯酚废水,测定了在进水苯酚质量浓度逐渐递增的条件下反应器中苯酚和COD的去除率;同时,在此基础上考察了生物膜干质量(suspended solid,SS)、挥发性干质量(volatile suspended solid,VSS)、活性生物量、脱氢酶活性(dehydrogenase activity,DHA)、胞外聚合物(extracellular polymer substances,EPS)的变化特征,并进一步分析了各指标之间的相关性,以期为反应器处理苯酚和其他含酚类化合物废水的应用提供参考。
活性污泥-生物膜一体化反应器对废水中苯酚的降解性能
Degradation performance of phenol in wastewater by activated sludge - biofilm integrated reactor
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摘要: 利用活性污泥-生物膜一体化反应器处理含苯酚废水,考察了反应器对苯酚和COD的处理效果以及反应器运行中生物膜干质量(SS)、挥发性干质量(VSS)、活性生物量、脱氢酶活性(DHA)、胞外聚合物(EPS)的变化,探究了生物膜特性与废水处理效果之间的关系。结果表明:在进水苯酚质量浓度由50 mg·L−1逐步提高到500 mg·L−1的过程中,苯酚和COD去除率均呈先降后升的趋势;当进水苯酚质量浓度为250 mg·L−1时,反应器能适应苯酚冲击,苯酚和COD去除率分别稳定在97%和60%以上;当进水苯酚质量浓度为500 mg·L−1时,苯酚去除率可达到99%,同期SS、VSS、活性生物量及DHA(22.03~57.07 mg·g−1)的变化亦反映出生物膜性能的提升,说明反应器对苯酚质量浓度变化的适应能力较强。此外,EPS质量分数为42.99~310.51 mg·g−1,蛋白质(PN)与多糖(PS)的质量比为0.67~1.39,且当初始苯酚质量浓度为250 mg·L−1时,PN/PS值最高,EPS亲水性低,生物膜可高效降解苯酚。以上研究结果表明,逐渐提高进水苯酚质量浓度能有效提高活性污泥-生物膜一体化反应器对苯酚的适应性和降解率。
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关键词:
- 苯酚 /
- 活性污泥-生物膜一体化反应器 /
- 脱氢酶活性 /
- 胞外聚合物
Abstract: An activated sludge-biofilm integrated reactor was used to treat phenol wastewater. The removal efficiencies of phenol and COD by the reactor, as well as the variations of suspended solid (SS), volatile suspended solid (VSS), active biomass, dehydrogenase activity (DHA) and extracellular polymer substances (EPS) of biofilm, were investigated. The results showed that the removal efficiencies of phenol and COD decreased firstly and then increased with the increasing of phenol concentration from 50 mg·L−1 to 500 mg·L−1. When the phenol concentration increased to 250 mg·L−1, the reactor was able to phenol shock, and the removal efficiencies of phenol and COD stabilized above 97% and 60%, respectively. When the initial phenol concentration was 500 mg·L−1, the phenol removal efficiency could reach 99%. The changes of SS, VSS, active biomass and DHA(22.03~57.07 mg·g−1) during the same period could reflect the improvement of the reactor treatment efficiency, implying that the adaptability to phenol for the reactor was enhanced. In addition, the mass fraction of EPS and mass ratio of protein (PN) / polysaccharides (PS) were in the range of 42.99~310.51 mg·g-1 and 0.67~1.39, respectively. When the initial phenol concentration was 250 mg·L−1, the highest PN/PS ratio occurred and EPS had low hydrophilicity, which indicated that biofilms could efficiently degrade phenol. The results showed that gradually increasing phenol concentration could effectively improve the adaptability of the biofilm reactor to phenol and its removal efficiency. -
表 1 不同阶段苯酚质量浓度
Table 1. Phenol concentration at different stages
运行时
间/d初始苯酚质量
浓度/(mg·L−1)运行时
间/d初始苯酚质量
浓度/(mg·L−1)1~5 50 31~35 350 6~10 100 36~40 400 11~15 150 41~45 450 16~20 200 46~50 500 21~25 250 51~55 500 26~30 300 56~60 500 表 2 各指标之间的相关性分析
Table 2. Correlation analysis between indicators
指标1 指标2 相关系数r P SS VSS 0.88 <0.01 SS COD 0.94 <0.01 SS 磷含量 0.31 >0.05 磷含量 苯酚去除率 0.88 <0.01 DHA 苯酚去除率 0.88 <0.01 磷含量 DHA 1 <0.01 PN/PS 苯酚去除率 0.30 >0.05 注:相关系数r为2个指标的皮尔森相关系数,P<0.01表示2个指标有显著的相关性。 -
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