Isolation Of A N-vinylpyrrolidone-degrading Bacterium And Its Degradation Characteristics, Immobiliziton And The Degradation Of NVP In Synthetic Wastewater

N-vinylpyrrolidone?NVP? is a common raw material widely used in many industries,it is mainly used for the production of homopolymers,cosmetics,adhesive,coating and pharmaceuticals.In the European and American countries,the demanding of NVP reached 10,000 tons per year,and it is indispensable in the chemical industrial products.NVP was inevitable released into environment during not only the synthesis but also the application process.In addition,NVP is a typical nitrogen heterocyclic compound?NHC?,which is usually toxic,teratogenic,and mutagenic.Various remediation process including chemical,physical and biological methods have been developed for the removal of pollutants.Among them,biological degradation is cost effective,easy to operate,without secondary pollution and environmental friendly.In this study,a highly effective NVP-degrading strain,ZF1,was isolated from the acclimated activated sludge.The strain cloud use NVP as the sole carbon and nitrongen source for growth.Based on morphological,physiological and biochemical properties,combining with 16S rRNA gene sequence analysis,ZF1 was identified as Arthrobacter ureafaciens.When cultured in LB liquid medium,the logarithmic period of strain ZF1 was between 6?36 h.After 36 h,the growth of strain ZF1 became stable and after 54 h,the growth of strain was slower,and the biomass began to decrease.Strain ZF1 had a better growth between pH 7.0?9.0 and temperature 25?3?.The optim al condition w as pH 7.0,temperature 30?,N aCl concen tration of 7.0 g/L.Environmental conditions such as pH,temperature,inoculum and metal ions had effects on the NVP degradation by strain ZF1.The optimal degradation conditions for strain ZF1 to degrade NVP was temperature 30?,pH betw een 7.0?9.0,and inoculation of 3%.Strain ZF1 could degrade 200 mg/L NVP within 60 h completely at the optimal condition.In addition,most of the metal ions have a different level of inhibition on NVP degradation.Among them,Fe³⁺ had almost no influence,but Cu²⁺,Ni²⁺ and Ag⁺ possessed a stronger inhibitory effect.Strain ZF1 was successfully immobilized on bamboo-based activated carbon?BBAC?.Compared with free cells,the immobilized cells have a better performance towards NVP degradation.The immobilized cells were then reused in three sequential cycles.The results indicated that the time needed for NVP removal was decreased as the increased reuse cycles.The biodegradation efficiency of BBAC immobilized strain ZF1 was enhanced gradually.The NVP degradation by immobilized cells fitted well with the first-order kinetics.The reaction constant decreased with the increase in NVP initial concentration.Finally,the free cells and immobilized cells were added into sequencing batch reactors?SBR?to treat NVP synthetic wastewater.After the setup of SBR,the operation was divided into three phases,during which the influent NVP concentration was increased and hydraulic retention time?HRT?was decreased gradually.The results illustrated that,the reactor with immobilized cells possessed a better capacity for resisting the organic/hydraulic loading shock than the other one.