周期搅拌低高径比SBR中好氧造粒及生物演替

Aerobic Granulation and Ecological Succession in a Periodically Stirred SBR with Low Height to Diameter Ratio

颗粒污泥的培养方式、基质和反应器影响颗粒的物理和生物特性以及传质效能,进而影响除污效果。在高径比(H/D)分别为2.5(P反应器)和4.4(S反应器)的全好氧鼓风曝气SBR中,以番茄酱废水为基质,结合生物相诊断及高通量测序等技术,考察低表观气速下连续和停歇两种搅拌方式的好氧颗粒污泥形成情况,定量计算了由搅拌机所激发的转动剪切力大小,并确定了较适宜的搅拌转速。结果表明,水平搅拌下的两种低高径比反应器相继颗粒化成功,但连续搅拌的SBR(H2/D2为4.4)中成熟颗粒均值粒径为714μm,小于停歇搅拌(H1/D1为2.5)的1.25 mm,且前者形成的颗粒多为红棕色。当P和S反应器的剪切力分别在0.159~0.186和0.188~0.247 N/m2时,剪切力度越大,颗粒越圆润,密实度越高,超过此范围后,大颗粒解体成片状。运行稳定以后,可观察到累枝虫、钟虫和轮虫等成为优势微生物,预示出水水质良好。高通量测序结果显示,在连续和停歇搅拌条件下,微生物多样性均有提高,P和S反应器的Shannon指数由3.90分别增至5.08和4.70,但停歇式搅拌中的脱氮除磷菌更具优势。在一定的鼓风曝气配合下,停歇式搅拌可更好地在低高径比反应器中培养出性能优良的颗粒污泥。

The culture mode,substrate composition and reactor design for aerobic granulation have an impact on the physical and biological characteristics as well as mass transfer efficiency of the granules,consequently influencing the decontamination efficiency.Utilizing tomato sauce wastewater as the substrate,in conjunction with biophase diagnosis and high-throughput sequencing technology,the development of aerobic granular sludge under continuous and intermittent stirring modes at low superficial gas velocity was investigated in an aerobic blast aeration SBR with H/D ratios of 2.5(P reactor)and 4.4(S reactor),respectively.The rotational shear stress induced by the mixer was quantitatively calculated to determine the most suitable stirring speed.The two types of reactors with low height to diameter ratio were successfully consecutively granulated under horizontal stirring.However,the mean particle size of mature granules in the continuous stirring SBR(H2/D2 of 4.4)was 714μm,which was less than 1.25 mm in the intermittent stirring SBR(H1/D1 of 2.5),and the granules formed in the former were predominantly reddish brown.When the shear stress of P and S reactors was within the ranges of 0.159-0.186 N/m2 and 0.188-0.247 N/m2,respectively,the granules tended to become more rounded and denser as the shear strength increased.Beyond this range,excessive shear stress caused large granules to disintegrate into sheets.After achieving stable operation,the presence of dominant microorganisms such as Epistylis,Vorticella and rotifer was observed,indicating favorable effluent quality.High-throughput sequencing revealed an increase in microbial diversity under both continuous and intermittent stirring conditions.The Shannon index of P and S reactors increased from 3.90 to 5.08 and 4.70,respectively.However,the denitrification and phosphorus removal bacteria were more dominant in the intermittent stirring condition.The granular sludge with good performance could be achieved in the reactor with a low height to diameter ratio through a specific combination of blast aeration.