Distribution,Adsorption And Degradation Of Typical Cardiovascular Drugs In Urban Sewage Treatment System

Nowadays,cardiovascular disease has become the primary threat to human health.With more than 420 million patients worldwide,the number of patients is still rising,leading to increased consumption of related drugs.Due to continuous use and discharge,cardiovascular drugs are detected in different environmental media such as domestic sewage,surface water,groundwater and drinking water.Although cardiovascular drugs were detected in trace concentrations,they were still toxiced to aquatic organisms and posed a potential threat to the environment and human health.At present,there are few reports on the distribution and behavior of cardiovascular drugs in wastewater treatment plants?WWTPs?.Therefore,we selected typical cardiovascular drugs as the research object to detect the concentration distribution in the influent of WWTPs and evaluate the consumption pattern by WBE in order to explore the usage patterns and regional differences of cardiovascular drugs.At the same time,we carried out its adsorption behavior on the sludge and UV degradation research,trying to explore its migration and degradation rules in the WWTPs.Related research findings are as follows:?1?The concentrations of four cardiovascular drugs?including metoprolol,bezafibrate,gemfibrozil,and atenolol?in influent samples from two WWTPs in Guangzhou and Zhuhai cities of Guangdong Province were N/A⁸89.73 ng·L^-1,slightly higher than the data reported in previous literature in China,but much lower than that in developed countries.The drug consumption patterns in Guangzhou and Zhuhai were MET>BZB>GFB>ATE.Compared with the other five cities in China,the total consumption of four cardiovascular drugs was the highest in Guangzhou,followed by Beijing,Wuxi,Chongqing,Shanghai and Zhuhai,the lowest consumption was Xiamen.Compared with developed countries,similar consumption of cardiovascular drugs was observed in Guangzhou,but a lower use level was observed in other cities in China.?2?The adsorption process of metoprolol,bezafibrate,gemfibrozil,and atorvastatin onto sludge was a two-step process:a rapid adsorption followed by a slow one.The adsorption equilibrium was about 8 h.The adsorption kinetics showed that the second-order kinetic equation fitting better,indicating that the adsorption process was dominated by chemical adsorption.The adsorption of the four drugs on the sludge showed a good correlation with the Freundlich model,and the order of Freundlich coefficient of the four drugs was consistent with the actual equilibrium adsorption order obtained from the adsorption kinetics experiments.The adsorption reaction was a spontaneous exothermic reaction,and the low temperature inproved the adsorption capacity.The acidic condition was more conducive to the adsorption of four drugs;the increase of ionic strength inhibited the adsorption of metoprolol and promoted the adsorption of the other three drugs.?3?Under UV irradiation,the kinetics of photodegradation of four drugs followed pseudo-first-order kinetic,and photolysis rate decreased with the increase of initial concentration.The photolysis of four drugs included direct photolysis and self-sensitized photolysis of reactive oxides such as·OH and ¹O₂.The photolysis of BZB?GFB and ATO were self-sensitized photoreaction process dominated by ¹O₂,and MET mainly depend on direct photolysis.With the increase of pH,the photolysis rates of MET and GFB decreased,the photolysis rates of BZB increased first and then decreased,and the photolysis rates of ATO increased.NO₃^-,NO₂^-inhibited the photodegradation of MET?BZB and GFB,but slightly promoted ATO photolysis;NH₄⁺had no significant effect on the photodegradation of four drugs;FA inhibited the photodegradation of four drugs.Six intermediates were detected in the BZB UV photolysis process.The possible degradation pathways of BZB mainly included ether bond cleavage,hydroxylation and amide bond cleavage.