Reserach On Water Treatment Technology Of Modified Sepiolite Loaded Bio-composited Enzyme

The lower number and activity of denitrifying bacteria causes that the removal rate of NO₃^-and NO₂^-is low for the influence of external environmental factors,such as carbon source,nitrate concentration,p H value and temperature,in the biological nitrogen removal process of traditional high ammonia nitrogen wastewater.Combining immobilized biological enzyme technology and biofilm water treatment technology can effectively improve the water treatment effect of high ammonia nitrogen wastewater.In this thesis,we investigated the effect of modified sepiolite particles loading bio-composited enzyme on the NH₃-N,NO₃^-,NO₂^-and other pollutants removal effect in high ammonia nitrogen wastewater by loading nitrate reductase and nitrite reductase on the surface of modified sepiolite.The main research contents of this thesis include three parts:（1）Preparation and characterization of modified sepiolite particles.First,modified sepiolite particles under different modification process including acid modification,thermal modification and combined acid with thermal modification and modification conditions including concentration of hydrochloric acid and calcination temperature are prepared,and the optimal modification process and modification parameters are screened out.Then,sepiolite raw ore,purified sepiolite particles and acid-modified sepiolite particles were analyzed by XRD;finally,purified sepiolite particles,acid-modified sepiolite particles,thermal-modified sepiolite particles and combined acid with thermal modified sepiolite particles were analyzed by SEM.（2）Modified sepiolite particles immobilized bio-composited enzyme.Firstly,the nitrate reductase and nitrite reductase were co-immobilized on the surface of combined acid with thermal modified sepiolite particles,and then the optimal immobilization parameters was screened by single factor test and orthogonal test,and finally researched the enzymatic properties of the immobilized bio-composited enzyme.（3）Research on water treatment effect of modified sepiolite particle loading bio-composited enzyme.Researched the effect of different hydraulic retention time or water treatment fillers including combined bio-composited enzyme with thermally acid modified sepiolite particle and combined acid with thermal modified sepiolite particles on NH₃-N,NO₃^-and NO₂^-removal rate in wastewater by single factor test.The main research conclusions of this thesis include three parts:（1）Combined acid with thermal modification was the optimal modification process of purification-sepiolite.The optimal modification parameters of modified sepiolite were that the concentration of HCl was 4.0 mol/L and the roasting temperature was 500°C.At this time,the specific surface area of sepiolite was 175.6 m²/g,which was 694%higher than that of purified sepiolite.（2）The optimal immobilization parameters of bio-composited enzyme were that the enzyme concentration was 10.00 mg/m L,the immobilized p H value was 6.5,the immobilized adsorption time was 8.0 hours,the immobilized glutaraldehyde content was 0.5%and the coupling time was 2.5 hours.modified sepiolite particle loading bio-composited enzyme has high p H stability,thermal stability and storage stability.（3）The removal rates of NH₃-N,NO₃^-and NO₂^-in water treatment device with modified sepiolite particle loading bio-composited enzyme as filler are higher than those of water treatment device using thermal-acid modification sepiolite particles as filler with the increase of running time or hydraulic retention time.The removal rates of NH₃-N,NO₃^-and NO₂^-in water treatment device with bio-composited enzyme as filler were 95%,91%and 90%respectively when the water treatment device runs stably.The removal rates of NH₃-N,NO₃^-and NO₂^-in water treatment device with modified sepiolite particle loading bio-composited enzyme as filler were 96%,96%and 97%respectively when the hydraulic retention time reached 10 hours.It showed that modified sepiolite particle loading bio-composited enzyme can effectively improve denitrification capacity of water treatment device.