不同饥饿时间下稳态好氧颗粒污泥系统的特性和动力学分析

The characteristics and kinetic behaviors of steady-state aerobic granules under different aerobic starvation

较长的饥饿时间是好氧颗粒污泥驯化形成的关键条件.但在稳态颗粒污泥系统中,饥饿时间长短对颗粒污泥的影响还不清楚.因此本实验采用四个序批式反应器(SBR),分别在好氧饥饿时间为1、2、3和4h(R1～R4)条件下运行,研究了饥饿时间对稳态好氧颗粒污泥系统的运行和特性等方面的影响.结果表明:对于稳态的好氧颗粒污泥系统,较长饥饿时间已不是保持污泥颗粒化的关键因素,系统在饥饿时间缩短后依然会保持污泥颗粒化和稳定运行效果.四种饥饿时间条件下反应器中COD去除效果没有表现出明显差异,COD平均去除率都几乎为98%以上.但在不同饥饿时间条件下,好氧颗粒污泥的性质有很大差别.在35天实验运行中,与较长饥饿时间相比,饥饿时间的缩短会使污泥中胞外聚合物含量降低,但PN/PS值会提高约6%左右,好氧颗粒直径增大.同时,当饥饿时间大于2h会使颗粒污泥中丝状菌过度生长,SVI30值升高约1.5倍,并且导致颗粒的物理性质降低.但是,动力学分析指出R1～R4的有机污染物降解速率在0.25～0.29h-1之间,较短饥饿时间的系统虽具有较高的qmax值,可是并不明显.并且R1～R4系统的饱和常数(K)和产率系数(Y)分别在5.39～8.45mg/L和0.391～0.746kgMLVSS/kgCOD,较短饥饿时间的系统会具有较高的COD出水浓度和剩余污泥产率.综上,好氧颗粒污泥驯化成功后,稳态的颗粒污泥系统不再需要在较长饥饿时间条件下运行,可以适当缩短反应时间,这不仅仅可以节约运行成本,降低不必要的能源消耗,还可以使系统具有较高的稳定性能.

A brief review of aerobic granulation shows that the longer aerobic starvation was an important factor in the formation of aerobic granules, but little information could be found currently available on the essential role of aerobic starvation at steady-state aerobic granules. Thus, this study investigated the characteristics and kinetics of mature aerobic granules in SBR, which performed visible differences at aerobic starvation of 1 h, 2 h, 3 h and 4 h （R1-R4） respectively. Results indicated that the longer starvation was not a key factor on steady-state granular system. All reactors could keep sludge granulation and stable operating, and the COD removal rate of four reactors was above 98%. However, different aerobic starvation showed an obviously effect on the characteristics of aerobic granules. In 35 days, due to the lower starvation, the production yield of extracellular polymeric substance was reduced, but the ratio of polysaccharides to proteins of granules was increased by 6%, and the size granules still increased. Meanwhile, the longer starvation （〉2 h） would cause overgrowth of filamentous bacteria, thereby weak the physical characteristics and increase the SVI30 value of granules. In addition, kinetic behaviors of mature aerobic granules showed that the maximum specific COD removal rates （qmax） was 0.25-0.29 h-1 （R1-R4）, those of four reactors kept the similar level. The apparent half rate constant （K2） and biomass yield （Y） of granules were 5.39-8.45 mg/L and 0.391-0.746 kgMINSS/kgCOD in R1-R4, the reactor had a higher COD effluent and biomass yield under the lower starvation. Thus, the steady-state aerobic granules with low aerobic starvation could successfully apply in SBR, thereby save the energy consumption and keep the stability of granular system.