好氧逆流化床生物反应器启动方案的研究

Study on Start-up Strategy of Aerobic Inverse Fluidized Bed Bioreactors

逆流化床作为一种新型的污水处理生物反应器在近年来得到了广泛关注。然而,对于应用于好氧污水生物处理的逆流化床反应器,快速有效的启动方法的研究尚未见相关报道。作者旨在探究好氧逆流化床生物膜反应器(AIFB)启动过程中操作模式和操作条件对于微生物膜形成和反应器处理效率的影响,并最终建立一个优化的快速启动方案。对聚乙烯颗粒(PE)进行了活性炭包覆,得到活性炭包覆颗粒(PEC)作为微生物载体,以启动过程中挥发性悬浮固体浓度(VSS)、附着挥发性固体浓度(AVS)、进出水化学需氧量(COD)、反应器有机负荷(OLR)作为主要标准以评价生物膜生长特性和反应器处理性能,依次研究了3种不同的启动方案且对有效的启动方案进一步进行了优化。实验发现:32 d的间歇培养启动方案和15 d的固定水力停留时间(HRT)为72 h的连续进水启动方案均获得了很低的生物膜浓度(AVS<50 mg/L)和较低的有机物去除能力。而6 d的逐渐降低HRT的连续进水快速启动方案获得了高生物膜浓度(AVS=514 mg/L)且在高有机负荷(6 gCOD/(L·d))的情况下实现了高COD去除效率(95%)。应用快速启动方案对比了活性炭包覆前后两种颗粒的启动过程,发现PEC颗粒获得了微生物膜浓度(AVS=514 mg/L)约为PE(AVS=269 mg/L)的两倍。好氧逆流化床启动过程中,短水力停留时间(HRT<3 h)是冲出悬浮微生物并使生物膜得到快速增长的关键,同时应用活性炭包覆的载体有利于生物膜形成。

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.