Study On Phenolic Wastewater Treatment Of Aerobic Biological Fluidized Bed And Hydraulic Characteristics Of Anaerobic-Aerobic Fluidized Bed

The hydraulic characteristics of anaerobic-aerobic fluidized bed and phenolic wastewater treatment research of aerobic fluidized bed were studied in the paper.The hydraulic characteristics, including pressure drop, gas holdup and oxygen mass transfer coefficient (KLa),were investigated. The results indicated that pressure drop increased along with the increase of supercrital liquid velocity both in two-phase and three-phase fluidized bed. The same trend of pressure drop was appeared with carrier percentage increased. In the three-phase fluidized bed, the results showed that a decrease in pressure drop increased superficial gas velocity. In addition, gas holdup changed that resulted in an increase in carrier percentage and superficial gas velocity and a decrease in gas holdup increased supercrital liquid velocity.The oxygen mass transfer coefficient(KLa) in the fluidized bed was also studied. The results demonstrated that a decrease and an increase in Ku with increasing carrier percentage and superficial gas velocity,respectively. The rise with gas velocity increase was attributed to high concentration dissolved oxygen that provided much probability to transfer between liquid and superface of the supports.The phenolic wastewater,including4-chlorophenol(4-CP), was treated in aerobic fluidized bed bioreactor. The removal efficiency in term of COD and4-CP were analysed by the effect of different factors. It was found that the method of rapid draw off sludge was fitting for the startup. The results revealed the optimum conditions as following: Hydraulic Retention Time(HRT)3.5h, aeration intensity38.98m3/m2·h (supercrital gas velocity1.08cm/s), adding glucose concentration600mg/L, reflux ratio120(supercrital liquid velocity2.05cm/s), influent4-CP concentration400mg/L.The continuous experiments with70d including three phases were conducted with treating wastewater mixed of4-CP, phenol and glucose. It was achieved a best results in terms of COD and4-CP efficiency, which got the COD removal of above90% and stable4-CP removal of80%. That was, fluidized bed bioreactor had a strong resistant in organic loading. In whole-day biodegradation experiments of three phases, it was proved that phenol promoted the biodegradation rate of the4-CP. Besides, biofilm thickness and VSS adhered to particles surface were observed that thickness and VSS increased slight along with increasing the concentration of phenol in different three phases. At last, SEM was adopted to represent the space structure and distribution of bacterium on theWCPs.