Experimental Study On Treatment Of Antibiotics In Water By Photocatalytic Composite Oxidation Technology

In recent years,with the continuous improvement of human medical standards and the rapid development of agricultural undertakings,the demand for antibiotics is increasing.While antibiotics have greatly improved the quality of life of people,they have also been detected in the natural environment more and more frequently as an emerging pollutant.Although several antibiotics commonly detected in the environment have been maintained at a lower concentration level,due to the characteristics of antibiotics,lower concentrations of antibiotics can also bringresistant bacteria to the environment and lead to ecological imbalance.Antibiotics are usually complex in structure and have certain ecotoxicity,which makes it difficult for traditional water treatment processes to produce very effective treatment effects.Photocatalytic technology can produce a large amount of oxidizing active radicals,which can produce non-differential oxidation of organic pollutants in water,and has the advantages of mild reaction conditions and no secondary pollution and has received extensive attention in the field of refractory organics processing.This topic uses the self-developed photocatalytic composite oxidation technology?photocatalysis,vacuum ultraviolet and ozone oxidation organic integration?to conduct in-depth experimental research on the degradation and mineralization of antibiotic CIP and SMX.The main research contents are as follows:?1?The effects of pH changes in the reaction system on the degradation of CIP and SMX by ozone,vacuum ultraviolet,photocatalysis and complex oxidation of the three and the effects of mineralization CIP and SMX were studied.It was found that acidic conditions favored the degradation and mineralization of two antibiotics by ozone;The change of pH has no significant effect on the speed of vacuum ultraviolet degradation of CIP and SMX;It is more favorable for the mineralization of these two antibiotics by vacuum ultraviolet action in an alkaline environment;CIP is more susceptible to photocatalytic degradation and mineralization in a neutral environment,while SMX is more susceptible to photocatalytic degradation and mineralization under acidic conditions.In photocatalytic composite oxidation technology,the degradation of CIP and SMX is mainly vacuum ultraviolet acts,while mineralization of CIP and SMX is primarily photocatalytic;?2?By designing the response surface experiment,the three main influencing factors of pH and circulation flow and ozone mixed gas ventilation were optimized for the photocatalytic composite oxidation technology to treat CIP and SMX.The optimal conditions for the treatment of CIP are a circulating flow rate of 0.72 L/min,an ozone mixed gas aeration of 0.66 L/min,and a solution pH of 5.6,the mineralization rate of CIP reaches 76.01%.The optimum conditions for the treatment of SMX are a circulating flow rate of 0.77 L/min,an ozone mixed gas aeration of 0.63 L/min,a solution pH of 3.5,and a mineralization rate of SMX of 78.47%;?3?The mechanism of photocatalytic composite oxidative degradation of CIP and SMX was studied by the capture agent experiment.It was found that·O₂^-has the strongest oxidative degradation performance for CIP and SMX.The vacuum ultraviolet light with a dominant wavelength of 185 nm has the best degradation effect on CIP and SMX.The ozone and the ultraviolet light with a dominant wavelength of 254 nm have certain effects on the degradation of CIP and SMX;?4?The changes of antibacterial activity in the degradation and mineralization of CIP and SMX by photocatalytic composite oxidation were studied.The MIC experiment was carried out on the products of CIP degradation and mineralization using Escherichia coli as an experimental bacterium.The antibacterial activity of CIP was completely eliminated at 120min.The MIC experiment was carried out on the products of SMX degradation and mineralization by using Staphylococcus aureus as the experimental bacteria.The antibacterial activity of SMX was completely eliminated after 30 min of reaction.It is proved that the composite oxidation technology can degrade and mineralize antibiotics,thereby eliminating its antibacterial activity;?5?Through the experimental study on the simulation of actual antibiotic-containing fish wastewater,under the action of photocatalytic composite oxidation technology,the CIP contained in the water sample was completely degraded within 90 min,and the water sample still had strong antibacterial activity.When the reaction was carried out until 270 min,the antibacterial activity in the water sample was completely removed,indicating that the photocatalytic composite oxidation technology has a good removal effect on the antibacterial activity of antibiotics in the actual wastewater,and is expected to be popularized in practice.