Enhanced Biodegradation Of Pollutants Based On Sieve Plate Tower Biofilm Reactor

Achieving industrial wastewater treatment with high-efficiency and energy-saving is a long-term challenge in the field of water treatment.Traditional industrial wastewater treatment has the disadvantage of excessive energy consumption,which hinders sustainable development.Therefore,the task of high-efficiency and energy-saving treatment of industrial wastewater is still arduous.For the characteristics of major pollutants in each industrial wastewater,it is very important that a scientific bioreactor is designed to treat various types of sewage and reveal the biodegradation law of pollutants for achieving high-efficient and energy-saving sewage treatment.Here,we have invented a vertical biofilm bioreactor(VBBR),which has superior ability to treat pollutants without the need to provide additional aeration devices.Based on VBBR,we carried out degradation experiments on 2,4,6-trichlorophenol(2,4,6-TCP),nitrobenzene(NB)and p-nitrophenol(PNP),respectively,and obtained the following conclusions:(1)During bioremediation of wastewater containing TCP,nitrate,or nitrite,both dechlorination and denitrification are electron-required reactions.These reactions mutually inhibited each other by competing electron donors in the same reactor.This mutual inhibition can be alleviated to some extent by the addition of electron donors.Compared with nitrate,nitrite exhibited less competitive inhibition to TCP reductive dechlorination.(2)By controlling the operating conditions,both the anaerobic zone and the aerobic zone were formed simultaneously in the VBBR,thereby accelerating the biodegradation rate of the NB.Because NB was converted to AN under a single anaerobic condition,it was hard further to degrad,thereby inhibiting the degradation of NB.However,under a single aerobic condition,NB will produce more recalcitrant nitrophenol(PNP),resulting in a slow degradation rate of NB.When the dissolved oxygen(DO)concentration in the reactor(~0.5 mg/L)was controlled,the added exogenous electron donor accelerated the removal rate of NB.Increasing the exogenous electron donor accelerated the single-oxygen reaction rate of NB and AN,and increased the single-oxygen reaction rate of AN to alleviate the inhibitory effect of AN on NB in anaerobic zone.(3)Compared with the plastic-based VBBR,it is easier to form a robust biofilm on the surface of the Fe-based carrier,and the biofilm community has higher diversity and richness.When the addition of four concentrations of acetate,neither can change the fact that the rate of degradation of PNP in Fe-based VBBR is faster than that in plastic-based VBBR,and the concentration of acetate required to maintain the maximum degradation rate of PNP is only 2.5-mmol/L in Fe-based VBBR.After starvation treatment,it was found that the Fe-based VBBR has stronger anti-starvation ability,and the time required for the Fe-based VBBR to recover the activity of degrading PNP is much less than that of in plastic-based VBBR.(4)Compared with the plastic-based carrier,the Fe-based carrier is chemically active,and chemical corrosion occurs in nature environmentat to produce ferric iron.The ferric iron can serve as both the energy substrate of the bacteria and as a signal for the growth and development of the biofilm.Therefore,the Fe-based carrier promotes the growth and development of the biofilm,and forms a biofilm with a thicker structure and a better functional structure.In addition,the Fe-based carrier generates ferric iron as an electron acceptor for microorganisms inside the biofilm,ensuring that extracellular electrons can be transmitted bidirectionally in the biofilm,which improves the rate of extracellular electron transport.