高含固厌氧消化污泥流变特性

采用完全混合式反应器R1、R2和R3(搅拌频率分别设为不搅拌、每10 min转动5 min和每10 min转动8min),在序批式运行的状态下,考察了不同搅拌频率对高含固厌氧消化过程中污泥流变特性的影响,探究了污泥表观黏度降低的主要原因以及污泥流变特性与各项物化指标的关系。结果表明,各个反应器消化污泥表观黏度μ值在发酵的前4天均出现大幅降低,下降幅度依次达到73.3%、77.8%和80.0%,从厌氧装置设计和运行的角度来看,脱水污泥高含固厌氧消化具有可行性。各反应器消化污泥的含固率(total solid,TS)以及挥发性固体(volatile solid,VS)占TS的比例VS/TS与表观黏度μ值以及稠度系数K值呈现显著性的指数关系,而污泥颗粒中胞外聚合物(extracellular polymeric substance,EPS)的含量与污泥表观黏度之间的相关关系则较弱。厌氧消化的初始阶段,微生物(主要是水解菌与产酸菌)的作用是污泥黏度急剧降低的主要原因。

Rheological characteristics of sludge in high-solids anaerobic digestion

Three completely mixed reactors numbered R1, R2 and R3 were used to investigate the effect of stirring frequencies on the rheological characteristics of sludge in the sequencing batch high-solids anaerobic digestion (AD), and the stirring frequencies of these three reactors were no mixing, 5 minutes' mixing in 10 minutes and 8 minutes' mixing in 10 minutes, respectively. The main reason why the apparent viscosity of sludge was reduced through AD, as well as the relationship between rheological properties and physic-chemical parameters were also studied. It was revealed that a sharp decrease (73.3%, 77.8% and 80.0%, respectively) of the sludge apparent viscosity existed in the three reactors during the first four days' fermentation. High-solids AD using dewatered sludge as feedstock was approved to be feasible when considering the design and operation of anaerobic devices. The concentrations of total solid and volatile solid were indicated to display a significant exponential relationship with the apparent viscosity and consistency coefficient in all three reactors. However, it indicated that the relationship between the concentration of extracellular polymeric substance and sludge rheological behaviors was unremarkable. The activity of microorganisms, especially hydrolysis and acid-forming bacteria, was revealed to be responsible for the sharp decrease of apparent viscosity at the primary stage of AD.