Study On Removal Mechanism Of Typical PhAcs In Tail Water Of Municipal Wastewater Treatment Plant By Modified Biological Sand Ratio Process

Pharmaceutically active compounds(PhACs)are widely used for the treatment of bacterial diseases in humans,and some are applied to livestock and fish for disease prophylaxis and treatment or for growth promotion.Large amounts of PhACs and their metabolites are continuously released into environmental compartments such as rivers,lakes,even ground water and soil,because all kinds of drugs were misused seriously for lack of scientific direction.Thetransportation,transformation,ecological toxicology and controlof PhACs have therefore provoked considerably scientific attention around the world over the past decade.In China,there are few reports on this aspect.And more than 70% of China's sewage treatment plants did not specifically for the construction of PhACs removal process(or section).Therefore,it is necessary to study a new type of advanced treatment process to remove PhACs,so as to reduce the pollution of water environment caused by PhACs.In this study,a Piranha solution and KH-550 hydrolysate and ferric salt as the quartz sand modifier,modified quartz sand the surface becomes uneven,by scanning electron microscopy(SEM),the surface characterization of the modified quartz sand filter before and after X ray diffraction analysis,infrared spectroscopy and organic carbon content.The adsorption kinetics and isothermal adsorption equilibrium were investigated in general,hydrophilic,hydrophobic modification and iron ion modified based on(bio)adsorption process of quartz sand of PhACs;on the quartz sand modified before and after effects of Biological Mulching before and after adsorption of PhACs on the analysis;the adsorption mechanism and the microorganism in the coated quartz sand in the contribution rate of removal of PhACs.The results show that:(1)The three kinds of modified quartz sand were modified by using Piranha solution,KH-550 solution and iron salt as modifier,and the particle size was 1.0mm ~1.7mm.Tetracycline,ciprofloxacin and metoprolol were chosen as the research object in this study.After Piranha treatment,the surface impurities of quartz sand by oxidation treatment showed mesh structure,specific surface area increases,so the hydrophilic modification of quartz sand on the adsorption of PhACs had the best removal effect;compared with the ordinary quartz sand,hydrophobic modificationand iron ion modified quartz sand for three PhACs the removal effect have different degrees of decline.(2)The results of adsorption kinetics can be found based on the modified quartz sand and bio coated quartz sand of PhACs static adsorption were basically reached equilibrium in 2H process,the static adsorption of PhACs on modified quartz sand coated quartz sand and biological are in line with the pseudo first order kinetic model,the adsorption mechanism was physical adsorption on the surface.(3)Based on the experimental results of isothermal adsorption equilibrium,can be found when the test temperature changes between 288.15 K and 309.15 K,the Langmuir adsorption isotherm model can better describe the adsorption behavior of static isothermal test of TCN,CIP and MTP modified quartz sand coated quartz sand and biological.The more the temperature is close to 298.15 K,the larger the static adsorption capacity of the modified quartz sand and the biological coated quartz sand on PhACs.When the pH is in the 2.0 to 12.0 range changes,effects of static adsorption of metoprolol was not affected by pH value,but the strong acid environment is conducive to the static adsorption of tetracycline and ciprofloxacin,concluded that the modified quartz sand coated quartz sand and biological adsorption mechanism mainly to tetracycline and ciprofloxacin is the main mechanism of cation adsorption,adsorption of metoprolol is the surface adsorption.When the K+,Na+ and Ca2+were added into the PhACs solution,the adsorption effect was reduced to some extent,and the inhibition effect of Ca2+ was higher than that of K+ and Na+.(4)Based on the results of scanning electron microscope,can be found in bio coated quartz sand surface of coccus,bacillus,bacillus,short and long Arthrobacter extracellular polymers formed biofilm structure and complex porous,the biofilm has obvious effect on the strength of PhACs cut;by batch experiments,found on coated quartz sand the PhACs cut filter contains microbial adsorption,adsorption and biodegradation of three ways,each way with the contribution rate of drug varieties showed significant differences,such as hydrophobic modification,iron ion modified quartz sand coated and ordinary biological degradation rate of ciprofloxacin was higher than 40%;while the other bio coated quartz sands to PhACs the degradation rate of only 0 to 9.84%.