外源Ca2+对SBR启动期活性污泥胞外多聚物的动态影响

利用无机物如Ca~(2+),加快活性污泥反应器启动,强化活性污泥絮体性能和结构稳定性,受到越来越多的重视.采用序批式反应器,研究进水中添加Ca~(2+)对反应器启动期活性污泥沉降性能和胞外多聚物的影响.结果表明运行至28 d,与进水中不添加Ca~(2+)的反应器(对照反应器)相比,进水中添加150 mg·L~(-1)外源Ca~(2+)的反应器中活性污泥MLSS和MLVSS值分别高出了89.6%和75.6%,SVI值则降低了47.9%;活性污泥胞外多聚物总量增加了76.4%,多糖增加了28.8%,蛋白质减少了31.6%,添加150 mg·L~(-1)外源Ca~(2+)的反应器中污泥胞外多聚物中多糖/蛋白质值为68.8,对照反应器的活性污泥胞外多聚物多糖/蛋白质值仅为36.6.三维荧光光谱和红外光谱分析表明外源Ca~(2+)导致活性污泥胞外多聚物组分发生了变化.实验结果为进水中添加外源Ca~(2+)改善活性污泥沉降性能提供了基础数据.

Evolution of Extracellular Polymeric Substances of the Activated Sludge with Calcium Ion Addition During Set-up Period of Sequencing Batch Reactors

Great attention has been paid to accelerate the start-up period and enhance floc properties and structural stability in activated sludge reactors with the aid of inorganic chemical agents such as calcium ion. The laboratory-scale sequencing batch reactors (SBRs) were operated continuously for 35 days to investigate the effect of calcium ion (Ca²⁺) on the physicochemical properties and evolution of extracellular polymeric substances (EPS) of activated sludge during set-up period. When compared to the control (non-calcium ion addition), the addition of 150 mg·L^-1Ca²⁺ to the influent significantly increased the mixed liquid suspended solids (MLSS) and the mixed liquid volatile suspended solids (MLVSS) by 89.6% and 75.6% on 28 d, respectively, and decreased the sludge volume index (SVI) by 47.9% following SBRs set-up. Compared with the control system, the contents of EPS, polysaccharides (PS) and proteins (PN) were increased by 76.4%, 28.8% and 31.6% under the condition of Ca²⁺ dosage of 150 mg·L^-1. The PS/PN ratio was 68.8 for Ca²⁺ addition, compared to only 36.6 for the control reactor. Analysis using three-dimensional excitation emission matrix fluorescence spectroscopy and Fourier transform infrared spectrum revealed that Ca²⁺ addition changed the compositional characteristics of EPS. Results from this study provided a fundamental knowledge basis for the improvement of the settling properties of activated sludge with calcium ion addition.