【作者】 郝赟；

【导师】 刘勇；

【作者基本信息】 天津大学 ， 环境工程， 2009， 硕士

【摘要】 在能量密度为0.05W·mL-1和pH范围3.0～12.0条件下,研究了超声波辐射以及热作用对污泥溶胞效果的影响,考察剩余污泥的溶胞效果与溶胞条件的关系。通过环境扫描电镜(SEM)技术分析了超声波、酸、碱以及热作用对污泥中微生物的形态影响以及各种预处理方法对污泥溶胞效果的影响关系。同时考察了低强度超声波对溶解性化学需氧量(SCOD)的声化降解作用,探索了超声波在协同碱对污泥溶胞过程中的作用机理。结果表明,溶解性化学需氧量(SCOD)、溶解性磷(SP)和溶解性糖(SA)含量随pH增大均呈先降后升趋势,而且强碱性环境有利于污泥溶胞。超声波辐射可显著提高污泥溶胞率,而且pH越大超声波辐射改善的溶胞效率越高,SCOD随pH呈指数增长趋势。实验条件下,SCOD随超声波时间均呈线性关系,超声波／碱协同污泥溶胞为一级反应。另外,溶胞效果SCOD数据随污泥浓度呈线性增加。依据上述规律,提出了污泥超声波碱协同溶胞的4参数数学模型SCCD=k0 exp(k1pH2＋k2pH)Cs(t+k3)并通过54组试验数据,应用非线性优化技术得到模型参数,该数学模型回归指数R2为0.872。为了对超声波／碱污泥溶胞技术中经济成本的分析,也研究了污泥浓度以及pH对耗碱量的数学模型及其参数。利用数学模型可视化地分析了剩余污泥溶胞条件和污泥浓度对溶胞效果和成本影响关系,并采用等高线技术分析了溶胞效果与溶胞成本相互关系,明确了超声波／碱剩余污泥溶胞优化规律和方向。低强度超声波的机械作用和热效应在协同碱对剩余污泥溶胞中的主要作用是分散污泥颗粒、改善碱在污泥颗粒缝隙中传质速率、强化碱与剩余污泥细胞的化学反应、以及促进剩余污泥胞外物质的脱附溶解,而超声波声化降解作用可以忽略。超声波／碱的协同溶胞过程机理和效果的研究,以及数学模型的建立和分析为改善剩余污泥溶胞效果、降低溶胞成本,为污泥源头减量化技术的探索和创新提供了实验和理论依据。更多还原

【Abstract】 The effect of ultrasonic irradiation with energy density of 0.05 W·mL-1 and thermal action on activated sludge cell lysis under pH ranging from 3.0 to 12.0 has been studied experimentally in detail. The relationships between efficiencies and conditions of cell lysis were also studied. Through environmental scanning electron microscope (SEM), the effects of ultrasound, acid, alkaline and thermal action on the microorganism shape in sludge were analysised. In this paper, the biodegradation action of low intensity ultrasound on SCOD was investigated. And the breakage mechanism of activated sludge by the combination action of low intensity ultrasound and alkaline was also studied.The results indicated that the concentrations of soluble chemical oxygen demand (SCOD), soluble phosphor (SP) and soluble polysaccharide (SA) reduced with pH first, and then increased. Strong alkaline circumstance would benefit for cell lysis. Ultrasonic irradiation could largely improve the efficiency of cell lysis, moreover, the higher the pH, the higher the lysis efficiency enhanced by ultrasonic treatment, and SCOD increased exponential with pH. Under the conditions of experiment, the contents of SCOD increased linearly with time. Cell lysis by ultrasonic/alkaline combined treatment was first order reaction. Also the increasing of effect of cell lysis (SCOD) was linear along with the of the sludge content. Based on the above principles and 54 groups of experimental data, a mathematic model with 4 parameters and index of regression of 0.872, describing the relationships between SCOD and pH, irradiation time and the sludge concentration, has been obtained using no-linear optimization method. In order to analysis the cost of cell lysis, the relationship between the amount of alkaline consumed and pH and sludge concentration, has also been obtained using no-linear optimization method. Based on the above mathematical models, using matlab software and the contour line technique, the relationships between operation conditions and cell lysis efficiencies and cost were visually analyzed. Some useful information for the optimization of cell lysis by ultrasound/alkaline was presented. The mechanical and thermal effects of low intensity ultrasound, in the coordination of alkaline are to disperse the sludge particles, improve the mass transfer of alkaline in sludge and strengthen chemical reaction between alkaline and sludge, as well as accelerate the desorption and the dissolution of extracellular polymeric substances, but the biodegeneration effect of low density ultrasonic wave may be neglected.Studying the breakage mechanism and efficiencies of activated sludge by the combination action of low intensity ultrasound and alkaline, and establishing and analyzing mathematical model which have provided the experimental and the theory basis for improving the efficiency of cell lysis, reducing the cost, and the exploration and the innovation of sludge source reduction technologies.更多还原