好氧逆流化床生物反应器启动方案的研究

With the increasingly stringent wastewater discharge standard and increasing demand for efficient wastewater treatment technology around the world, the inverse fluidized bed bioreactor as a newly developed biofilm reactor for wastewater treatment has gained extensive attention from researchers in recent years. However, the start-up stage of inverse fluidized bed bioreactor used in aerobic wastewater treatment process is still under-explored. This work aimed to explore the effects of operational parameters on the biofilm formation and the reactor performance in the start-up stage of aerobic inverse fluidized bed bioreactors (AIFB) and establish an optimal short-term start-up strategy. Activated carbon coated polyethylene particles (PEC) were prepared in house and used as bio-carrier. The volatile suspended solids (VSS), attached volatile solids (AVS), chemical oxygen demand (COD) of the influent and the effluent, and the organic loading rate (OLR) in the reactor were recorded to evaluate the biofilm accumulation activity and reactor performance. Three start-up strategies were studied sequentially and the start-up strategy which successfully established a bioreactor was further optimized. It was found that the 32-day intermittent cultivation strategy and the 15-day continuous inflow strategy with fixed HRT of 72 h both achieved low biofilm concentrations (AVS<50 mg/L) and limited COD reduction abilities. However, the 6-day continuous inflow start-up strategy with gradually shortened HRT established a high biofilm concentration (AVS=514 mg/L) and a satisfied COD removal efficiency of 95% under a high OLR of 6 gCOD/(L•d). The performance of the reactors using PE and PEC were compared and found that the biofilm concentration of PEC (514 mg/L) was twice bigger than that of PE (AVS=269 mg/L). In the start-up of AIFB, short hydraulic retention time (HRT<3 h) was the key factor to wash out suspended microorganisms and facilitate the biofilm growth and the carrier coated with activated carbon could promote the biofilm formation.