Removal Of Trace Organic Compounds By Activated Sludge

Trace organic compounds are the compounds whose content is very low in the environment. Its concentration levels usually in the μg/L~ng/L and μg/g~ng/g. Tr OCs include pharmaceutical active compound(Ph ACs), endocrine disrupting chemicals(EDCs) and personal care products(PCPs), etc. EDCs is the substance that can interfere with the function of endocrine systems in human or animal and cause abnormal effect.Recently, revealing more and more negative effects, EDCs and Ph ACs become a pressing concern because of their significant implications on ecosystems and potential impacts on public health. Water is a kind of important medium transferring Tr OCs. Therefore, controlling concentration of Tr OCs in water can reduce the possibility of Tr OCs entering organism. By studying the migration and transformation law of sulfmethoxazole(SMZ), carbamazepine(CBZ), bisphenol A(BPA) and 17α-ethinylestradiol(EE2) in the sewage, this thesis provides some basis of controlling Tr OCs concentration for wastewater treatment plant.First of all, this thesis studied extraction method in the aqueous phase and detect method applying high performance liquid chromatography(HPLC) of four kinds of Tr OCs. Using VWD detector and ZORBX SB-C18 column(5μm, 4.6×150mm, Agilent Co.), the optimal chromatography conditions are got. The column temperature is 35℃. The mobile phase is methanol and water(65:35,v/v). The sample volume is 20μL. The flow rate is 1.0m L/min. The detection wavelength is 268 nm, 227 nm, 223 nm and 268 nm successively. The detection time is 10 min. Using solid phase extraction(SPE) to enrich water samples, the optimal extraction is got. The p H of water sample is adjusted to 3. After loading sample with the speed of 5m L/min, the ultrapure water is used to leaching. Then, 3m L of methanol is used to elute the targets after vacuum drying. Finally, 65% methanol is used to make the volume reach 1m L. The recovery rate of SMZ, CBZ, BPA and EE2 is 100.72%, 100.37%, 100.52% and 98.85% respectively. Extract SMZ in sludge by ultrasonic solvent extraction. The recovery rate is 94.38%.In the static adsorption experiment, the activated sludge was inactivated by adjusting the p H value to acid. The adsorption kinetics, adsorption isotherms, desorption isotherms, adsorption thermodynamics and adsorption mechanism of four Tr OCs were studied. The results are drawn.1)The adsorption of SMZ, CBZ, BPA and EE2 on inactivated sludge was a quick process. In the first 15 min of adsorption, the concentration of four Tr OCs decreased rapidly in aqueous phase, and then it decreased slowly. After 5 hours of adsorption, the concentration of Tr OCs in aqueous phase was basically stable. At that time, the adsorption reached balance. The pseudo-second order kinetics equation could well describe the equilibrium curves of four Tr OCs in inactivated sludge. The correlation coefficients were greater than 0.99. The equilibrium adsorption capacity of four Tr OCs in inactivated sludge was in the order of qe-CBZ<qe-SMZ<qe-BPA<qe-EE2.2)Adsorption isotherms of four Tr OCs in inactivated sludge could well fit Freundlich adsorption model and linear adsorption model. But their adsorption mechanism was not the same. SMZ relied more on surface adsorption adsorbed by inactivated sludge. CBZ, BPA and EE2 relied more on distribution function.3)Four Tr OCs adsorbed by inactivated sludge might desorb into aqueous phase. The desorption coefficient was larger than the adsorption coefficient for four Tr OCs. The amout of SMZ is the least among four Tr OCs when desorption happened.4) Adsorption of four Tr OCs in inactivated sludge was exothermic and spontaneous.Experiment was carried on to study the degradation ability of activated sludge. Use SBR to degrade SMZ. Mass balance was adopted to calculate the total amount of SMZ in one cycle. The results indicated that SMZ was adsorbed by activated sludge during the anaerobic stage. Then SMZ was degraded during the aerobic stage. In the anoxic stage, the concentration of SMZ in solid phase and aqueous phase changed little.