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好氧颗粒污泥是指在有氧环境条件下微生物相互聚集形成的生物聚集体[1]。与传统活性污泥相比,好氧颗粒污泥具有生物量高、结构稳定、沉降性能好、耐冲击负荷强和处理构筑物占地面积小等优点[2]。与厌氧颗粒相比,好氧颗粒具有启动时间短、操作温度低等特点。由于颗粒结构内部存在氧浓度梯度,故能在一定程度上实现多种生物群落共存,以完成同步脱氮除碳。有的研究表明,好氧颗粒污泥不能在自然条件下出现,必须在具有强选择压力的特定条件下培养。以往研究采用特殊操作条件(如调节水力剪切力、好氧饥饿时间、水力停留时间等)来培育,也有的研究通过调整进水负荷(如有机负荷率(OLR)、化学需氧量和氮之比(C/N))来促进颗粒化形成[3-4]。
目前,很多产业生产排出高C/N的污水,如氮肥行业、化工行业、制药行业等。活性污泥处理高C/N污水存在系统不稳定、污泥容易膨胀、处理效果不理想等问题[5-6]。好氧颗粒污泥因结构致密,有胞外聚合物(extracellular polymeric substances,EPS)保护,颗粒内部可截留多种功能菌群,是高C/N污水可选择的理想处理工艺,且高C/N也是启动好氧颗粒污泥反应器的一种条件[7-8]。冯殿宝等[9]用高C/N的番茄废水成功培养好氧颗粒污泥,COD和
${\rm{NH}}^+_4 $ -N去除率分别为90%和85%。杨丹丹等[10]用C/N为10~24的汽车涂装废水培育出好氧颗粒污泥,COD和${\rm{NH}}^+_4 $ -N去除率分别为85%和95%。然而,目前关于高C/N培养条件下颗粒污泥的群落结构研究较少,颗粒污泥高效脱氮除碳的机制尚不清楚。因此,本研究拟在实验室规模的序批式反应器(sequencing batch reactor,SBR)中实现高负荷条件下好氧颗粒污泥的培养和高效稳定的同步脱氮和除碳,并考察这一培养条件下好氧颗粒污泥内微生物的群落结构特点,为探寻其高效脱氮除碳的原因提供参考。
高负荷条件下好氧颗粒污泥同步脱氮除碳特性及微生物群落结构分析
Characteristics on simultaneous nitrogen and organic carbon removal and microbial community structure analysis of aerobic granular sludge treating high strength wastewater
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摘要: 为研究高负荷条件下好氧颗粒污泥的形成过程、同步脱氮除碳效果和微生物群落结构特点,构建了一个序批式反应器(sequencing batch reactor,SBR)。结果表明,C/N=40进水条件下能够完成颗粒化,成熟后的好氧颗粒污泥呈表面光滑结构紧实的椭球体。随着颗粒粒径增大,其比好氧速率提高、含水率下降、沉降性能变好、生物量增加。颗粒形成过程产生的胞外聚合物(extracellular polymeric substances,EPS)先增加后受水质冲击减少,之后又明显提高,整个过程中多糖与蛋白质之比(PS/PN)持续下降,EPS中的蛋白质对颗粒的形成影响较大。SBR中的好氧颗粒污泥能够同时高效去除进水中的COD、
${\rm{NH}}^+_4 $ -N和TN,去除率分别为94%、96%和93%,反应器的反硝化性能良好。C/N=40时,采用MiSeq高通量测序方法对成熟好氧颗粒污泥中的群落结构进行研究,发现存在促进颗粒化的优势菌门(包括Saccharibacteria、Proteobacteria、Bacteroidetes、Actinobacteria、Firmicutes和Chloroflexi)。同时,在颗粒污泥中,异养硝化、好氧/缺氧反硝化菌属丰度较高,表明异养硝化-好氧/缺氧反硝化菌属可能存在于好氧颗粒污泥中。Abstract: To investigate granular formation process, simultaneous nitrogen and organic carbon removal efficiency, community characteristics of aerobic granular sludge treating high strength wastewater, a sequencing batch reactor (SBR) was set up. The results showed that the granulation can be completed under the influent condition of C/N=40. The mature aerobic granules were compact spheroids with a smooth surface. With the increase of particle size, the specific oxygen uptake rate (SOUR) and biomass increased, the settling performance became good, while the water content decreased. During the granular formation process, extracellular polymeric substance (EPS) increased at first and then reduced due to the influence of water quality, and finally increased significantly. The ratio of polysaccharides to proteins (PS/PN) continued to decrease throughout the whole process, and proteins in EPS have an important effect on granular formation. The aerobic granular sludge in the SBR could simultaneously remove COD,${\rm{NH}}^+_4 $ -N and TN with high efficiencies of 94%, 96% and 93%, respectively, and the denitrification performance of the reactor was good. High-throughput sequencing by MiSeq revealed that the dominant bacteria in aerobic granular sludge to promote granulation at C/N=40 were following: Saccharibacteria, Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes and Chloroflexi. Meanwhile, the relative abundances of heterotrophic nitrifiers, aerobic/anoxic denitrifiers in granular sludge were high, indicating that heterotrophic nitrification - aerobic/anoxic denitrification process occurred in aerobic granular sludge. -
表 1 人工配水组分
Table 1. Components of synthetic wastewater
阶段 CH3COONa/(g·L−1) 蔗糖/(g·L−1) 蛋白胨/(g·L−1) NH4Cl/(g·L−1) KH2PO4/ K2HPO4 微量元素溶液/(mL·L−1) Ⅰ 0.51 0.38 — 0.16 投加量保证进水pH为7.0~8.0 3 Ⅱ 1.38 1.01 0.24 0.23 投加量保证进水pH为7.0~8.0 3 表 2 46 d时SBR内颗粒污泥粒径分布
Table 2. Size distribution of aerobic granular sludge in SBR after 46 d cultivation
编号 粒径/mm 质量分数/% 1 ≤0.25 7.1 2 0.25~0.38 1.4 3 0.38~0.83 24.1 4 0.83~1.18 29.6 5 1.18~1.7 14.9 6 1.7~2.36 9.1 7 ≥2.36 13.9 -
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