Study On The Effect Of Salinity And Antibiotics On The Efficiency Of Short-cut Nitrification And Denitrification

In recent years,the problem of water pollution has become more and more serious,and the types of pollutants in the water have gradually increased.As a big country in the use of antibiotics,my country has produced a large amount of salt-containing antibiotic wastewater,and antibiotics have even been detected in urban sewage.However,the conventional biological treatment technology of urban sewage treatment plants cannot effectively remove antibiotics,and antibiotics will have a toxic action on water treatment microorganisms and weaken the sewage treatment effect.Therefore,it is very important to explore the mechanism of antibiotics on the denitrification effect and microorganisms,and to find ways to reduce the toxic action of antibiotics on microorganisms.In addition,as a new type of biological denitrification technology,the SHARON has significant advantages compared with the traditional process,and the salinity has a certain promoting effect on the SHARON.Therefore,this study used the SHARON for the denitrification treatment of salt-containing antibiotic wastewater,and explored the effects of salinity and antibiotics on the treatment efficiency of SHARON.In this research,the SBR was used as the operating equipment of the SHARON.Under the operating conditions of dissolved oxygen 0.5～1 mg/L,p H 7.5～8.0,temperature 30°C,it lasted 30 operating cycles,and SHARON was successfully started.Craft.After the removal effect was stable,the removal rates of COD,NH₄⁺-N and TN reached 98.77%,88.03%,and 77.83%respectively,and the accumulation rate of NO₂^--N reached 82.57%.Then Na Cl was added to the reactor,and controlled the salinity to increase the salinity from 0 g/L to 18 g/L with a salinity gradient per 1.8 g/L.Detected the changes of pollutant removal effect and activated sludge extracellular polymer in this process.As the salinity increased,The removal rate of COD remained above 90%,which was not significantly affected by the salinity;before the salinity was not higher than 10.8g/L,the NH₄⁺-N removal rate and TN removal rate were weakly affected,and could still reach 82.92%and 63.17%,the accumulation rate of NO₂^--N is 89.35%;after the salinity was risen above 10.8 g/L,the removal rate of NH₄⁺-N,the removal rate of TN,and the accumulation rate of NO₂^--N all decreased to a certain extent;After rose to16.2 g/L,the denitrification effect of the reactor was extremely weak,and the salinity increase was stopped.After the salinity dropped to 10.8 g/L again,the removal rate of COD,NH₄⁺-N,and TN in the reactor quickly recovered and was higher than before,rising to 97.36%,94.07%,and 92.63%,respectively,and the accumulation rate of NO₂^--N reached 89.58%.The microorganisms in the SHARON will produce more EPS under the stress of salinity.Among them,the proportion of polysaccharides will increase to balance the adverse effects of osmotic pressure and weaken salinity.The proportion of protein in EPS will be changed and new characteristics will be produced.The influence of salinity is reversible,and the salt tolerance of microorganisms in the SHARON can be improved by increasing the salinity tolerance limit and then reducing the salinity,and the denitrification efficiency can be improved.After the stable reaction was restored,tetracycline was added and the concentration increased from 0 mg/L to 10 mg/L.The removal rate of COD,NH₄⁺-N and TN all decreased to varying degrees,and the removal rate of COD decreased from97.36%to 91.25%.,The removal rate of NH₄⁺-N decreased from 94.07%to 84.77%,and the removal rate of TN was most affected from 92.63%to 70.73%;the accumulation rate of NO₂^--N basically stabilized at around 90%.Tetracycline can accumulate in activated sludge and has a continuous inhibitory effect on microorganisms in the SHARON.Tetracycline stresses microorganisms to produce more EPS,most of which are proteins.EPS can combine with tetracycline to form a more stable complex,which quenches the fluorescence of proteins in the 3D-EEMs.This is the self-protection mechanism of microorganisms.Finally,the influence of temperature,tetracycline,and Na Cl on the SHARON under the interaction of temperature,tetracycline,and Na Cl was analyzed by RSM.The order of correlation from strong to weak is temperature>salinity>tetracycline concentration.Increasing the salinity within the tolerance limit can promote the production of more EPS by microorganisms to reduce the adverse effects of tetracycline;it can also promote the accumulation of NO₂^--N to improve the efficiency of short-range nitrification,and realize the operation of the SHARON under low temperature conditions.