Removal Efficiency And Mechanism Of Carbamazepine By Protein Bioflocculant

Pharmaceuticals and Personal Care Products (PPCPs) have brought potentially enormous hazard to aquatic species and human because of their bio-accumulate effect to organisms, leading to an attention of environment fields. The persistence and trace characteristics of PPCPs make them difficult to remove by current methods and processes. According to the issues above, this research developed removal effect and mechanism study of PPCPs based on favorable water-clean property and broad-spectrum application of bioflocculant.This research started from seed selection of bioflocculant micro-organisms. After screening,100strains flocculant organisms were acquired. Combined with bioflocculant micro-organisms in our lab and from literature, a database of bioflocculant organisms seeds information was set up. Bioflocculant species J-1was selected for micro-organism flocculants preparation and application. After identified, J-1belongs to Klebsiella variicola, GenBank accession number is KF770752, microbial culture preservation number is CGMCC NO.6243. According to the growing property and fermentation characteristic study of J-1, It’s hereditary stability was stable, the maximum specific growth rate was0.44h-1, the maximum predicted biomass was2.05g/L. the most optimum flocculant yield conditions of bioflocculant bacterium J-1were inoculation6.5mL/100mL, pH7.5, temperature35oC, rotating speed140r/min, fermentation time15h, and the flocculating rate under such condition was97.32%, bioflocculant yield rate2.51g/L.The primary metabolism products, MFX, of bioflocculant bacterium J-1was secreted to supernatant of fermentation liquor. The results of color reaction, enzymolysis reaction, and three dimensional fluorescence spectra revealed that MFX is macomolecule organic substance consisted of polysaccharide and protein, which the content of protein was1.6times higher than polysaccharide. The results of stability test and thermogravimetric analysis proved that under condition of netral of slightly basic, temperature of20~80oC, the flocculants active property could be kept above85%. Meanwhile, MFX has the property of relatively high molecular weight as high as8,509,760Da. The result of infrared spectroscopy indicated that microbial flocculants MFX contains many functional groups such as amidogen, amide, carboxyl, and hydroxyl. According to the physical and chemical characteristics of MFX, ethanol extraction method was applied to extract its major active ingredients. The most optimum extraction conditions are concentrating the fermentation supernatant volume to1/2of former volume, ethanol quantity3.5 times than fermentation volume, extracting time15h, ethanol concentration100%. Under such condition, the extracted concentration of flocculant avtive ingredients was2.543g/L. Compared to previously, the liquid solution was more sticky, and flocculating effect promoted from97.35%to98.06%.Microbial flocculant MFX showed a favorable removal effect of several typical PPCPs such as estrogen, carbamazepine, sulfamethoxazole. Under conditions of flocculant inoculum7mL, flocculant favorable drug addition0.1mL, pH7.5, reaction temperature0.5h, the removal efficiency of carbamazepine was more than81.75%. Compared to the regular four inorganic and organic flocculants, microbial flocculant MFX had a prominent advantage in removing carbamazepine. Sewage and secondary sedimentation tank effluent were selected to study microbial flocculant MFX removal effect of carbamazepine in real wastewater, and the result showed that under conditions of pH8, flocculant inoculum8.5mL, flocculant favorable drug addition0.1mL, reaction time13min, microbial flocculant MFX could remove carbamazepine by75.03%and69.76%. Compared to synthesis carbamazepine water, removal efficiency was decreased a little, because of substances such as suspended solids (SS), total nitrogen (TN), total phosphorus (TP) competed with carbamazepine for the absorption position of microbial flocculant.According to the flocculant behavior and potential Zeta changes of microbial flocculant MFX, it is probable that the major mechanism of microbial flocculant MFX removing carbamazepine are absorbtion bridging, capturing and sweeping effects. Concentration of90%ethanol was applied to dissociative adsorb carbamazepine, and the dissociative adsorption rate was62%. Compared to the SEM images of pre-absorbed, after absorbed and dissociative adsorbed microbial flocculant MFX, the absorption of carbamazepine of MFX was partial reversible. Ultrasonic wave method was applied to broken dissociative absorbed sediments,23%carbamazepine was released, and8.14%remained was unknown to where. The result of three-dimension fluorescence spectrum proved that both physical absorption and chemical absorption exist in the process of MFX removing carbamazepine. Absorption kinetics and thermal results showed that MFX removing carbamazepine was fit for pseudo-first order kinetics and Freundlich absorption isotherm. This result further proved that microbial flocculant MFX absorbing carbamazepine was the process of combination of physical and chemical absorption effects of absorption bridging, capturing and sweeping.