Kinetics Of Degradation Of Naphthalene By Ochrobactrum Anthropi Na-B Biofilm

Naphthalene is a polycyclic aromatic hydrocarbon（PAHs）pollutant with carcinogenic,teratogenic and mutagenic activities.Once it is released into the environment,it will cause serious harm to human health.As a result,naphthalene is listed as a priority pollutant by EPA.And as a green technology,biodegradation has become the first choice for solving polycyclic aromatic hydrocarbon pollution.In this study,Ochrobactrum anthropi Na-B（Na-B）was purified and separated.Naphthalene was used to form a biofilm as the sole carbon source.And the growth process of biofilm,the process of biofilm degradation for high concentration naphthalene and the mass transfer process of biofilm were studied.（1）The growth process of Na-B biofilm is closely related to bacterial inoculation amount,matrix concentration and hydraulic conditions.Under this experimental conditions,the specific growth rate of biofilm was the highest when the inoculation amount of bacterial suspension(OD₆₀₀=0.5)was 10%and the concentration of naphthalene was 20 mg/L,r=100 rpm.The growth regularity of Na-B biofilm accords with Capdeville’s division for biofilm growth stage,and the growth curve of quality of Na-B biofilm fit well with Langevin model.（2）The performance of naphthalene degradation by Na-B biofilm is related to the growth stage of biofilm,the area of biofilm,the initial dosage of naphthalene,temperature and pH.In the scope of this experiment,the biofilm has the strongest ability to degrade naphthalene while the biofilm is in increased logarithmic phase and pH=7.The larger biofilm area,higher temperature and lower concentration of naphthalene are beneficial to naphthalene degradation.The degradation rate of naphthalene by Na-B biofilm accords with the second-order reaction kinetics.（3）The mass transfer performance of Naphthalene in Na-B biofilm is related to the growth stage,initial Naphthalene concentration and temperature of the biofilm.In the initial stage of biofilm growth,the lower initial concentration of naphthalene and the higher temperature,the time for mass transfer to reach equilibrium is shorter.And the higher initial concentration of naphthalene,the higher temperature,the mass transfer flux of Na-B biofilm is higher.While the mass transfer flux has little relationship with the stage of biofilm growth.The mass transfer coefficient of Na-B biofilm decreased with the growth of biofilm,the increase of initial concentration of naphthalene and the decrease of temperature.The effect coefficient of diffusion resistance in biofilm on reaction rate is 1.00 and Thiele modulus is less than 0.5.It indicates that the internal diffusion resistance of the Na-B biofilm is negligible,and the reaction is the main rate limiting factor.