Experimental Study On The Sludge Characteristics Of Adsorption On PPCPs And Forward Osmotic Separation Of Them

With the rapid development of the detection technology of trace pollutants and the strengthen of environmental consciousness,pharmaceuticals and personal care products?PPCPs?have attracted much attention.As early as 1999,The German proposed the concept of pharmaceutical and personal care products?PPCPs?based on trace organic pollutants,which led to extensive research on this type of trace organic environmental pollutants in the world.Firstly,based on the Web of science database,the PPCPs related literature was statistically analyzed;The research on PPCPs during 1999²017 shows that the number of papers is increasing year by year,among them,the United States topping the list and China's fastest growth.The literature shows that PPCPs detection technology has made significant progress;Anti-inflammatory pharmaceuticals,antibiotics and antibacterial agents are the most studied types of PPCPs;Wastewater treatment plants are the most important point source pollution of PPCPs;Rivers,surface water,groundwater,lakes,oceans and drinking water are also contaminated by PPCPs to varying degrees;Adsorption is the most mentioned treatment method,and the treatment technologies of oxidation treatment,membrane separation removal,biodegradation and photocatalytic degradation are also making progress.In this study,the occurrence of seven typical quinolone antibiotics from three generations in excess sludge was investigated at trace concentrations using ultra-high performance liquid chromatography-tandem mass spectrometry?UPLC-MS/MS?.EPS facilitated adsorption independent of pH and quinolone antibiotic type,and the solid-liquid distribution coefficient decreased markedly as pH increased?pH 5⁹?.Metal ions bound in EPS were predominantly responsible for the adsorption of antibiotics in sludge,rather than the macroscopic size of the sludge floc.pH affected patterns of quinolone antibiotics,the zeta potential of sludge floc,and the contents of metal ions contained in sludge.The adsorption capacity of antibiotics first increased and then decreased with increasing pH in the range of pH 3¹1,reaching a maximum?20506,14458,10689,22854,20302,8494,and 29547 L/kg for CIP,ENR,LOM,MOX,NOR,OFL,and SAR,respectively?near pH=5,at which the cationic bridging of Ca²⁺and Mg²⁺bound in EPS played a major role owing to their larger ion radius and higher contents in excess sludge.Due to high surface heterogeneity of sludge,the Freundlich model was more suitable than the Langmuir model for describing the adsorption behavior of quinolone antibiotics.These results further reveal that the release of quinolone antibiotics adsorbed in excess sludge,with negative implications for the agricultural use of sludge.A simple and fast predicting method on the amount of PPCPs adsorbed in excess sludge is established,based on the solid-liquid partition coefficient?K_d?.By extensively collecting K_d values of PPCPs and applying Beijing's practical data,the amounts of PPCPs adsorbed in excess sludge were respectively calculated.Although the adsorbing efficiencies are not very high??20%?for most of PPCPs,a few of PPCPs can take a high share in the total adsorbing efficiency of PPCPs,reaching up to 88%in all 33 ordinary PPCPs.An ultimate approach to avoiding PPCPs in the sludge released into the environment would be incineration of the sludge.Forward osmosis is a new type of membrane separation technology,which relies on the osmotic pressure difference on both sides of the membrane as the driving force to spontaneously realize the water molecule transmission.Because of its low energy consumption and low membrane fouling,it has become advanced technology.Through experiments,the interaction between typical drugs?CIP,SMX and ACP?during the separation of positive osmosis membranes was studied.The results show that factors affecting pharmaceuticals rejection rate include:1)The number of pharmaceutical molecules determines the probability of collision between molecules;2)The pH determines the chargeability of the surface of the membrane and the morphology of the pharmaceutical molecules;3)the relative size of the membrane pores and the pharmaceutical molecules determine the membrane pore blockage;4)Neutralization exists between molecules of oppositely charged pharmaceutical.