Removal Of Tetracycline From Livestock Wastewater By Catalytic Ozonation With Modified Steel Slag

Antibiotics are typical refractory pollutants,which are difficult to degrade naturally after entering water bodies.The environmental problems caused by antibiotic residues have been gradually concerned by people.Livestock and poultry industry is an important part of the development of agriculture and rural economy in China.With the expansion of livestock and poultry industry scale,the demand for antibiotics is gradually increasing.At present,China accounts for more than 50% of the antibiotics used in the world’s livestock and poultry industry.Antibiotics contained in livestock and poultry wastewater induce resistance genes and interfere with microbial-driven nitrogen cycle process,which has become an important factor affecting human life safety and water eutrophication.As one of the advanced oxidation technologies,ozone catalytic oxidation technology has the advantages of good stability and high removal rate of organic pollutants.In this paper,the tetracycline(TC)is used as the target pollutant,using steel slag,iron slag and zeolite materials,studies the removal effect of catalytic ozone oxidation,explores the influence of different influence factors on antibiotic removal,and analyzes the catalytic oxidation mechanism.Provide a theoretical support for the treatment of antibiotic wastewater,and the test results show that:Among the three catalysts of zeolite,steel slag and iron slag,the adsorption performance of zeolite is higher than that of steel slag and iron slag,and the catalytic efficiency of steel slag is better than that of zeolite and iron slag.Zeolite is mainly TC adsorption,steel slag is mainly catalyzed by the decomposition of ozone into free radicals,and the catalytic effect of steel slag is related to the high content of Fe and Mn elements.The increase of ozone concentration will push up the removal rate of TC,and 3 mg / L ozone can reach 88.93%.600 ℃ high temperature roasting can effectively improve the TC effect of steel slag catalytic ozone oxidation.High temperature roasting can effectively improve the surface roughness,pore size and pore size of the catalyst.After modification,the specific surface area of steel slag is increased from 1.098 m2 / g to 48.651 m2 / g,the pore volume is increased from 0.002 cm3 / g to 0.225 cm3 / g,and the pore diameter is increased from 3.402 nm to14.142 nm.High temperature roasting effectively releases the active components of Mn O2,Mn2O3,Fe3O4 and Fe2O3 inside the steel slag,and the modified steel slag catalyst has good activity and stability.High-temperature roasting modified steel slag can effectively catalyze the ozone oxidation of tetracycline,and the TC removal rate can reach 95.1%.The increase of temperature has no obvious impact on the ozone catalytic process of modified steel slag,and the removal rate fluctuates within 3.5% at different temperatures.During the p H value increased from 2.0 to 10.0,the effect of ozone on treating TC first increased,then decreased,and the removal rate of TC increased from 76.3% to 95.2%.The concentration of ammonia nitrogen showed a negative correlation with the catalytic ozone process of steel slag.The ammonia nitrogen in the system increased from 10 mg / L to 70 mg / L,and the oxidation efficiency of the catalytic ozone system increased from 91.4% to 91.8%.At the reaction temperature is 40℃,p H=6,the volume load is 25 mg/L and no ammonia nitrogen influence,the steel slag catalytic ozone oxidation effect is the best.The active radical in the reaction system was determined by adding TBA and p-BQ,and the free radical was combined with the reaction intermediates and the catalyst elements...