a b s t r a c tLittle is known about the contamination level of antibiotics in swine wastewater in China. The highly complex matrix of swine wastewater, which generally has a chemical oxygen demand (COD) concentration as high as 15,000 mg/L, makes it difficult to detect antibiotics at trace levels. In this work, a highly selective and sensitive analytical method was developed for simultaneous determination of three classes of commonly used veterinary antibiotics including five sulfonamides, three tetracyclines and one macrolide in swine wastewater using solid-phase extraction (SPE) and liquid chromatography-mass spectrometry (LC-MS). The method detection limits (MDL) in the swine wastewater were determined to be between 5 and 91 ng/L, depending on specific antibiotics. Except sulfamethizole, all the other eight antibiotics were detected in the swine wastewaters collected from three concentrated swine feeding plants located in the Beijing (China) area, showing a concentration range of 0.62-32.67 g/L. These results reveal the representative concentration levels of selected antibiotics in the swine wastewaters of Beijing area.

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The combination of chlorine and UV (i.e., chlorine-UV process) has been attracting more attention in recent years due to its ready incorporation into existing water treatment facilities to remove PPCPs. However, limited information is available on the impact of total ammonia nitrogen (TAN). This study investigated two model PPCPs, N,N-diethyl-3-toluamide (DEET) and caffeine (CAF), in the two stages of the chlorine-UV process (i.e., chlorination and UV/chlor(am)ine) to elucidate the impact of TAN. During chlorination, the degradation of DEET and CAF was positively correlated with the overall consumption of total chlorine by TAN. Reactive nitrogen intermediates, including HNO/NO and ONOOH/ONOO, along with OH were identified as major contributors to the removal of DEET and CAF. During UV irradiation, DEET and CAF were degraded under UV/chlorine or UV/NHCl conditions. OH andCl were the major reactive species to degrade DEET and CAF under UV/NHCl conditions, whereas OCl played a major role for degrading CAF under UV/chlorine conditions. Numerical models were developed to predict the removal of DEET and CAF under chlorination-UV process. Chlorinated disinfection byproducts were detected. Overall, this study presented kinetic features and mechanistic insights on the degradation of PPCPs under the chlorine-UV process in ammoniacal water.

a b s t r a c tThe fate and seasonal variation of several typical endocrine-disrupting chemicals (EDCs), including estrone (E1), 17b-estradiol (E2), 17a-ethinylestradiol (EE2), estriol (E3), bisphenol A (BPA) and 4-nonylphenol (NP), were investigated in a municipal sewage treatment plant (STP) employing an anaerobic/ anoxic/oxic (A/A/O) process located in Beijing, China by monitoring their concentrations in both wastewater and activated sludge in four seasons throughout 2009. Results indicate that in summer, the examined STP could effectively remove 75.4% of E1 and more than 90% of all other studied EDCs from the wastewater. The biodegradation in the A/A/O process was the primary removal mechanism. Moreover, the removal of EDCs from the wastewater in the A/A/O bioreactor and their concentrations in the solid phase of return sludge exhibited an obvious seasonal fluctuation. The concentrations of EDCs in the effluent and return sludge were much higher in winter and spring than in summer and autumn, which was closely related to the microbial activity and the concentration of mixed liquor suspended solids (MLSS). Therefore, this study may raise a particular concern regarding the removal of EDCs from wastewater and the disposal of excess sludge in cold seasons.

Levofloxacin (LF) is a frequently detected fluoroquinolone in surface water, and permanganate (MnO) is a commonly used oxidant in drinking water treatment. This study investigated the impact of humic acid (HA) on LF degradation by aqueous MnO from both kinetic and mechanistic aspects. In the absence of HA, the second-order rate constant (k) of LF degradation by MnO was determined to be 3.9 M s at pH 7.5, which increased with decreasing pH. In the presence of HA, the pseudo-first-order rate constant (k) of LF degradation at pH 7.5 was significantly increased by 3.8- and 2.8-fold at [HA]:[KMnO] (mass ratio) = 0.5 and 1, respectively. Secondary oxidant scavenging and electron paramagnetic resonance tests indicated that HA could form a complex with Mn(III), a strongly oxidative intermediate produced in the reaction of MnO with HA, to induce the successive formation of superoxide radicals (O) and hydroxyl radicals (OH). The resulting OH primarily contributed to the accelerated LF degradation, and the complex [HA-Mn(III)] could account for the rest of acceleration. The degradation of LF and its byproducts during MnO oxidation was mainly through hydroxylation, dehydrogenation and carboxylation, and the presence of HA led to a stronger destruction of LF. This study helps better understand the degradation of organic micropollutants by MnO in drinking water treatment.

Besides, Fenton's reagent helped to not only remove total organic carbon (TOC), heavy metals (As, Cu and Pb) and total phosphorus (TP), but also inactivate bacteria and reduce wastewater toxicity. This work demonstrates that the integrated process combining SBR with Fenton's reagent could provide comprehensive treatment to swine wastewater. ª 2009 Elsevier Ltd. All rights reserved. IntroductionThe concern about the occurrence of antibiotics in the environment has been growing due to the potential evolution of antibiotic resistant bacteria. Antibiotics are widely used in concentrated animal feeding operations (CAFOs) around the world to treat the diseases and improve the growth rate of animals. In China, over 8000 tons of antibiotics are currently used as feed additives each year (Henan Animal Husbandry Bureau, 2009). Antibiotics are often added in the feed and water for animal feeding. However, the majority of antibiotics are excreted in feces and urine without adsorption and metabolism by animals (Sarmah et al., 2006). As a result, the potential environmental risks brought about by antibiotics are increasing along with the rapid advance of livestock industry. In fact, antibiotics have been frequently detected in the slurry and wastewater of CAFOs (Haller et al., 2002;Malintan and Mohd, 2006). Multiple classes of antibiotics with relatively high concentrations, commonly at >100 mg/L levels, were detected in swine waste storage lagoons in the United States (Campagnolo et al., 2002). In our previous work, eight antibiotics including four sulfonamides, three tetracyclines and one * Corresponding author. Tel.: þ86 10 62849632; fax: þ86 10 62923541. E-mail address: qiangz@rcees.ac.cn (Z. Qiang).A v a i l a b l e a t w w w . s c i e n c e d i r e c t . w a t e r r e s e a r c h 4 3 ( 2 0 0 9 ) 4 3 9 2 -4 4 0 2

The detailed sorption steps and biodegradation characteristics of fluoroquinolones (FQs) including ciprofloxacin, enrofloxacin, lomefloxacin, norfloxacin, and ofloxacin were investigated through batch experiments. The results indicate that FQs at a total concentration of 500μg/L caused little inhibition of sludge bioactivity. Sorption was the primary removal pathway of FQs in the activated sludge process, followed by biodegradation, while hydrolysis and volatilization were negligible. FQ sorption on activated sludge was a reversible process governed by surface reaction. Henry and Freundlich models could describe the FQ sorption isotherms well in the concentration range of 100-300μg/L. Thermodynamic parameters revealed that FQ sorption on activated sludge is spontaneous, exothermic, and enthalpy-driven. Hydrophobicity-independent mechanisms determined the FQ sorption affinity with activated sludge. The zwitterion of FQs had the strongest sorption affinity, followed by cation and anion, and aerobic condition facilitated FQ sorption. FQs were slowly biodegradable, with long half-lives (>100hr). FQ biodegradation was enhanced with increasing temperature and under aerobic condition, and thus was possibly achieved through co-metabolism during nitrification. This study provides an insight into the removal kinetics and mechanism of FQs in the activated sludge process, but also helps assess the environmental risks of FQs resulting from sludge disposal.