【作者】 刘绍根；

【导师】 俞汉青；

【作者基本信息】 中国科学技术大学 ， 应用化学， 2010， 博士

【摘要】 基于活性污泥对污水中有机污染物的初期去除作用开发出来的生物絮凝吸附工艺,在基建投资和运行费用较低的情况下可去除大部分污水中的有机污染物,对降低城市污水处理厂的投资和运行费用具有十分重要的现实意义。国内外对生物絮凝吸附工艺的系统构成、反应器结构形式及部分工艺参数如污泥浓度、停留时间等进行了研究,但对其工艺原理的认识不够深入,也未能建立描述该工艺的数学模型,其研究结果缺乏普适性。本论文通过小试系统研究并优化了生物絮凝吸附工艺的主要工艺参数,在解析其工艺原理的基础上建立了具有描述该工艺的数学模型,中试系统的稳定运行表明该工艺具有运行的可靠性和稳定性,其运行结果证明了所建数学模型的合理性和准确性,说明本研究的结果具有普适、性。本研究的主要成果如下：1.在分析生物絮凝吸附工艺各主要工艺参数的基础上,构建了生物絮凝小试系统；系统考察了气水比、絮凝时间、活化时间、污泥龄和回流比5个等主要工艺参数对系统污染物去除效果的影响,获得了生物絮凝吸附工艺的优化参数：气水比10：1,絮凝时间30min,活化时间2h,污泥龄6d,回流比40%-50%。2.对生物絮凝吸附工艺的污泥吸附特性进行了考察,结果表明该工艺对悬浮和胶体有机物的吸附效果好；污泥经活化后,吸附性能大大提高；伪二级动力学方程能更好地描述污泥对有机物的吸附特性,20℃下的伪二级吸附速率常数kads为0.816 g-COD/mg-MLVSS.h;添加抑制剂后的活性污泥比吸附率降低了10%左右,表明系统中仍存在微生物对有机污染物的生物降解作用；污泥的异养菌产率系数为0.69 g-COD/g-COD,污泥产量较高。3.根据对生物絮凝吸附工艺原理的剖析,引入吸附过程和水解过程,以ASM1模型为基础,建立了描述生物絮凝吸附工艺的数学模型；通过建立工艺过程动力学方程和物料平衡方程,对系统内的不同组分碳源进行了物料平衡分析；敏感分析结果表明,模型参数的敏感度从大到小依次为YH、μH、kH、KX、KS、kads、μA、bA,对敏感度较大的μH、kH、KX和Ks进行了参数估计；用生物絮凝小试系统的试验结果对模型进行了校正与验证,证明所建数学模型具有较高的准确性；应用所建数学模型对生物絮凝工艺参数进行优化的结果为：絮凝时间为40min、活化时间为1.5h、污泥龄为6d。4.以小试研究为基础,结合数学模型对工艺参数的优化结果,完成了生物絮凝中试系统的设计、安装和调试；水力负荷增大,中试系统对污水SS、COD和CODss去除效率大幅度下降,而SS和CODss去除率变化较小；污泥负荷在2-20 kgCOD/kgMLSSd之间变化,系统对COD和SS仍保持较高的去除率,而SCOD去除率随着污泥负荷的增加而降低；当回流比分别为50%和25%时,生物絮凝中试系统的COD平均去除率分别为70%和65%、NH3-N平均去除率分别为15%和10%、P043--P平均去除率分别为40%和20%；该工艺承受冲击负荷的能力较强；中试系统的运行结果进一步证明了所建数学模型的合理性和准确性,能够为污水处理厂的设计和运行提供理论指导。更多还原

【Abstract】 The biological flocculation and adsorption process, which is developed based on the rapid organic matter adsorption by activated sludge, can remove organic matters in domestic wastewater significantly at lower investment of infrastructure and operation costs. Its application is beneficial for reducing the investment of infrastructure and the operation costs simultaneously to construct wastewater treatment plants (WWTPs). At present, most studies on such a process are focused only on system structure, reactor configuration and influencing factors, such as solids retention time (SRT), hydraulic retention time (HRT). However, its working principle is not yet clearly understood and its kinetics is not sufficient. Also, a mathematical model for describing this process is not available and the results are ununiversal. Through systematic experiments, the key parameters of the biological flocculation process were optimized and a universal mathematical model was developed in this study. The developed model was further proven to be reasonable and accurate with a pilot-scale study, which indicated the results are universal. Main results of this study are as follows:1. A laboratory-scale study was performed after analyzing the key parameters of the biological flocculation and adsorption process. The influences of ratio of gas/water, coagulation time, activation time, SRT and recirculation ratio on the system performance were evaluated. The optimized parameters were determined as follows: gas/water ratio 10:1, coagulation time 30 min, activation time 2 h, SRT 6 d and recirculation ratio 40%-50%.2. The adsorption characteristics of activated sludge in the biological flocculation and adsorption process were investigated. The suspended and colloidal organic matters were adsorbed effectively. The absorption capability was improved greatly after activation. The adsorption of organic matters by activated sludge followed the pseudo-second-order kinetics. The adsorption rate constant kads was 0.816 g COD/mg.MLVSS.h at 20℃. The adsorption ratio decreased 10%after the addition of inhibitosr, indicating that the microbial biodegradation occurred in the process. The heterotrophic bacteria yield coefficient was estaimated as 0.69 g COD/g COD and sludge yield was high.3. Based on ASM1 and the working principle of the biological flocculation and adsorption process, a mathematical model, which included biological adsorption and hydrolysis processes, was developed. The carbon sources of system were analyzed on the basis of kinetic equation and mass balance. The results of sensitivity analysis demonstrated that YH,μH, kH, KX, KS, kads,μA, bA were more sensitive. The model was calibrated and verified with the experimental data. The optimized simulation results were found to be:coagulation time of 40 min, activation time of 1.5 h, SRT of 6 d.4. A pilot-scale biological flocculation and adsorption system was well designed, installed and operated based on the results of the bench-scale study and mathematical model simulation. The removal efficiency of suspended solids, chemical oxygen demand (COD), CODss decreased significantly with an increase in hydraulic loading rate, and the removal rate of SS and CODss changed slightly. The removal efficiency of COD and SS remained high, while the removal efficiency of SCOD decreased with an increase in sludge loading rate when it was in a range of 2-20 kgCOD/kgMLSSd. The average COD, NH3-N and PO43--P removal efficiency were 70%,15%and 40%, respectively, at a recirculation ratio of 50%. At a recirculation ratio of 25%, the average COD, NH3-N and PO43--P removal efficiency was 65%,10%and 20%, respectively. The biological flocculation process had a resistance to shock loadings. The results of the pilot-scale study further demonstrated that the developed model was reasonable and accurate and was able to provide a theoretical foundation for its design and. operation in WWTPs.更多还原