| Trace organic contaminants(TrOCs)is a new category of emerging environmental pollutant,mainly including drugs and personal care products,endocrine disruptors,pesticides,etc.,common organic chemicals in daily life and production.In recent years,with the increasing public awareness of environmental protection and the development of detection technology,TrOCs in the environment have gradually been detected,and they have received widespread attention due to their potential,persistence and biological toxicity.Owing to the inefficient removal of TrOCs by traditional sewage treatment processes,the effluent from urban sewage treatment plants is an important source of the diffusion of TrOCs into the environment.In this study,22 typical TrOCs in urban sewage were selected,and a set of high-performance liquid chromatography-mass spectrometry(UPLC-MS/MS)methods for quantitative detection of TrOCs in samples were established;The removal mechanism of TrOCs in municipal sewage in anaerobic membrane bioreactor(AnMBR)was investigated;the effect of different HRT,the physical and chemical properties of TrOCs itself and the indirect retention of membranes on the removal of TrOCs was studied when AnMBR was operating stably.In addition,on the basis of continuous experiments,sludge adsorption and biodegradable TrOCs removal were analyzed through batch experiments.This study also investigated the strengthening effect of Biochar on the removal of TrOCs by AnMBR.By comparing and investigating the changes in the migration process of TrOCs during the removal of TrOCs by the two processes,and discussing the enhanced removal mechanism of TrOCs by the Biochar-AnMBR process,it provides a reference for the application of advanced treatment technologies for TrOCs in sewage.The specific research conclusions are as follows:(1)The pretreatment recovery rates of the liquid and solid phase samples of 22 TrOCs are between 73.4±12.1%and 83±16%,respectively.The detection limit of the UPLC-MS/MS detection method is 0.04μg/L～1.63μg/L,the limit of quantification was 0.42 ng/L～16.3 ng/L,and the linear correlation coefficient line R~2was all greater than 0.99.This method provides valid data for reference for the application of UPLC-MS/MS technology to the detection of TrOCs in the water environment.(2)The AnMBR system in this experiment can achieve high-efficiency removal of COD under low HRT;running AnMBR under different HRTs has no obvious effect on the removal of TrOCs;AnMBR has a large difference in the removal rate of different TrOCs,of which SMX And TMP can be almost completely removed during the entire operation period of AnMBR,while the average removal efficiency of IBP,DCF,CMP and ketoprofen is less than50%.(3)The physical and chemical properties of TrOCs themselves are the main factors that determine their removal efficiency.The removal efficiency of AnMBR for hydrophilic TrOCs ranges from 21.1%to almost complete removal,while the removal efficiency of hydrophobic TrOCs is stable above 80%;those containing EDGs and EDWGs TrOCs are easier to be removed by the reactor,and most of the hydrophilic TrOCs containing EWGs are difficult to remove by AnMBR treatment;through mass balance calculation,the migration and distribution law of TrOCs in AnMBR is obtained.The removal path of TrOCs in AnMBR is first sludge adsorption After biodegradation.(4)The adsorption capacity of TrOCs depends on their hydrophobicity and ionization properties,which use log D and p K_aas characteristic parameters,respectively.There is a statistically significant positive correlation between the adsorption removal rate of AnMBR sludge and the log D value.For TrOCs with a p K_agreater than 7,the adsorption and removal by electrostatic interaction is enhanced;the improved Gompertz model is used to predict the biodegradation potential and biodegradation rate of the easily degradable and difficult-to-degrade TrOCs under anaerobic conditions.In the EDGs and EDWGs groups,large Most TrOCs are prone to biodegradation,especially the biodegradation potential of sulfamethoxazole,trimethoprim and naproxen is about 95%.(5)By comparing the removal effect of AnMBR reactor and biochar-enhanced AnMBR process on the number of 22 TrOCs,it is concluded that the biochar-enhanced AnMBR process can enhance the removal of TrOCs by AnMBR.The addition of biochar can completely remove TrOCs in a short period of time(10 days);with the operation of the reactor,the adsorption capacity of biochar weakens,and the final overall average removal rate of Biochar-AnMBR for TrOCs is increased by 5%compared with AnMBR.By analyzing the rules and mechanism of Biochar-AnMBR removal of TrOCs,the removal mechanism of biochar mainly enhances the removal of TrOCs by adsorption.For different types of TrOCs,according to their physical and chemical properties,the removal enhancement effect of biochar is different.Through the quasi-second-order kinetic model and the Langmuir adsorption isotherm model,it can be judged that the adsorption of TrOCs by biochar is the chemical adsorption of the monomolecular layer on the surface of the adsorbent,and its adsorption is characterized by uniform adsorption on the surface,mainly through the coupling of chemical bonds To complete,physical adsorption is supplemented;the adsorption capacity of biochar for TrOCs is mainly determined by the physical and chemical properties of pollutants,such as Log D and p K_a;in addition,the addition of biochar may change the characteristics of the sludge in the reactor,which is obviously strengthened.The biodegradable removal rate of refractory pollutants containing EWGs functional group is improved,so that the internal environment of the reactor is conducive to the removal of such refractory pollutants.This study established a series of methods for quantitative detection of 22 TrOCs in urban sewage,and achieved the effective removal of TrOCs through AnMBR and biochar enhanced treatment processes,which provided a useful exploration for the application of AnMBR technology and the research on the removal of TrOCs. |
PDF Full Text Request