活性污泥动力学模型的建立及在完全混合式污泥系统中的应用

首先建立了微生物衰减系数和污泥浓度、底物浓度的函数关系式,带入Lawrence-McCarty第一方程式得到了Logistic方程形式的微生物生长方程式.在分析污泥泥龄和污泥停留时间关系基础上,引入Monod方程建立了活性污泥动力学模型,推导证明了Lawrence-McCarty方程式是模型静态条件下的表达形式.用建立的活性污泥动力学模型对完全混合式污泥系统进行了模拟,并分析了水力停留时间Hydraulic retention time(HRT)和污泥停留时间Sludge retention time(SRT)对完全混合式污泥系统的影响,表明模型能很好地对活性污泥系统的动态过程进行模拟.根据模型编程画出了污泥系统相关变量关于HRT和SRT变化的三维曲面图,通过编程将复杂模型看作一定输入输出的函数,使得模型更易于应用和推广.     

Effect of acetate and propionate on the production and characterization of soluble microbial products (SMP) in aerobic granular sludge system

It is well known that soluble microbial products (SMP) derived from biological systems found in wastewater treatment plant effluent are responsible for chemical oxygen demand (COD). Aerobic granular sludge (AGS) is recognized as an efficient and innovative approach for wastewater treatment. Acetate and propionate as two dominant organic substances in wastewater need to be effectively removed before discharge. The aim of this study was to investigate the effectiveness of acetate and propionate to interfere with the accumulation, molecular weight (MW) distribution and composition of SMP in aerobic granular sludge (AGS) system using two identical sequencing batch reactors (SBR) named R1 and R2, respectively, thus reducing the COD. The results demonstrated that more SMP accumulated in R1 in presence of acetate compared to R2 treated with propionate. A positive correlation for SMP formation was detected as evidenced by aeration rates, but a negative correlation with hydraulic retention time (HRT). The MW distribution analysis suggested that small molecules (MW <3?kDa) were the dominant fraction of SMP in R1 and R2, accounting for 57–79% and 39–61%, respectively. In addition, gas chromatography-mass spectrometry (GC-MS) demonstrated that esters, alkanes, alkenes and alcohols were the predominant low-MW SMP in R1 and R2. More peaks were present in R2 (61) than R1 (46). Esters were the predominant SMP (39%) in R1, while alkanes were the predominant SMP (31%) in R2. Further, microbial community analysis indicated that more α- and γ-Proteobacteria groups which readily utilize low-MW SMP were found in R2 compared to R1-granules which may have contributed to less SMP accumulated in R2. The abundant genera in the granules were Zoogloea and Azoarcus, in particular, a greater quantity of Azoarcus was detected in R2 than R1-granules, which may be associated with higher degradation of aromatics in SMP.