The effect of slime accumulated in a long-term operating UASB using crude glycerol to treat S-rich wastewater

An up-flow anaerobic sludge blanket(UASB)reactor targeting sulfate reduction was operated under a constant TOC/S-SO2-4ratio of 1.5±0.3 g C/g S for 639 days using crude glycerol as carbon source.A filamentous and fluffy flocculant material,namely slime-like substances(SLS),was gradually accumulated in the bioreactor after the cease of methanogenic activity.The accumulation of SLS was followed by a decrease in the removal efficiencies and a deterioration in the performance.Selected characteristics of SLS were investigated to explore the causes of its formation and the effect of SLS on the UASB performance.Results showed that glycerol fermentation and sulfate reduction processes taking place in the reactor were mainly accomplished in the bottom part of the UASB reactor,as the sludge concentration in the bottom was higher.The accumulation of SLS in the UASB reactor caused sludge flotation that further led to biomass washout,which decreased the sulfate and glycerol removal efficiencies.Batch activity tests performed with granular sludge(GS),slime-covered granular sludge(SCGS)and SLS showed that there was no difference between GS and SLS in the mechanism of glycerol fermentation and sulfate reduction.However,the specific sulfate reduction rate of GS was higher than that of SLS,while SLS showed a higher glycerol fermentation rate than that of GS.The different rates in GS and SLS were attributed to the higher relative abundances of fermentative microorganisms found in SLS and higher relative abundances of sulfate reducing bacteria(SRB)found in GS.

进水水质成分改变引发的污泥粘性膨胀及控制

在研究强化SBR工艺除污性能时,由于可溶性淀粉投加导致进水水质成分发生改变,污泥沉降性能在短时间内迅速恶化,污泥出现大量的粘液。镜检发现,大量指状菌胶团异常增殖且丝状菌的数量也逐渐减少。实验结果表明,系统膨胀属于污泥粘性膨胀。停止可溶性淀粉和提高主反应池的DO浓度,污泥粘性膨胀并未得到恢复,但污泥粘液逐渐消失。粘液消失后,通过模拟前期进水水质成分和缩短泥龄,污泥粘性膨胀得以控制,污泥沉降性能在短时间内恢复。实验还研究了污泥粘性膨胀对污染物去除性能的影响。