Thyroid status in juvenile alligators (Alligator mississippiensis) from contaminated and reference sites on Lake Okeechobee,Florida, USA

Exposure to environmental contaminants has been shown to alter normal thyroid function in various wildlife species, including the American alligator (Alligator mississippiensis). Abnormalities in circulating levels of the thyroid hormone thyroxine (T₄) have been reported in juvenile alligators from several contaminated lakes in Florida. To further elucidate these functional thyroid abnormalities, this study examines the structure of thyroids and circulating T₄ concentrations from juvenile alligators collected from three sites of varying contamination on Lake Okeechobee, Florida. The following variables were used to characterize thyroid morphology: epithelial cell height, width and area, percent colloid, and follicle area. These variables were compared among study sites and between genders. No difference was detected in epithelial cell height, epithelial cell area, or follicle area among the sites, whereas significant differences in epithelial cell width (p=0.02) and percent colloid (p=0.008) were found. Animals from the most contaminated site (Belle Glade) had significantly greater epithelial cell widths and significantly less colloid present in their follicles compared to animals from the reference site (West). Gender did not have a significant interaction with site for any variable measured. Thyroxine (T₄) concentrations were elevated in the intermediately contaminated site (Conservation Area 3A) compared to the other sites (p<0.0001). It is proposed that the disruptions seen in Lake Okeechobee alligators are due to disruptions at both the thyroid and extra-thyroidal tissues.     

膜生物反应器生物降解与膜分离共作用特性研究

膜生物反应器实质是生物降解与膜分离相互影响,共同作用的过程,污泥浓度与通量之间存在一定的相关关系,膜分离对生和性能尤其是细菌活性有着重要的影响,而生物反应器内细菌胞外聚合物,溶解性有机物及微细胶体可能成为形成凝胶层导致通量下降的主要因素。     

Performance and fouling mechanism of direct contact membrane distillation (DCMD) treating fermentation wastewater with high organic concentrations

In this study,direct contact membrane distillation(DCMD)was used for treating fermentation wastewater with high organic concentrations.DCMD performance characteristics including permeate flux,permeate water quality as well as membrane fouling were investigated systematically.Experimental results showed that,after 12 hr DCMD,the feed wastewater was concentrated by about a factor of 3.7 on a volumetric basis,with the permeate flux decreasing from the initial 8.7 L/m~2/hr to the final 4.3 L/m~2/hr due to membrane fouling;the protein concentration in the feed wastewater was increased by about 3.5 times and achieved a value of 6178 mg/L,which is suitable for reutilization.Although COD and TOC in permeate water increased continuously due to the transfer of volatile components from wastewater,organic rejection of over 95%was achieved in wastewater.GC–MS results suggested that the fermentation wastewater contained 128kinds of organics,in which 14 organics dominated.After 12 hr DCMD,not only volatile organics including trimethyl pyrazine,2-acetyl pyrrole,phenethyl alcohol and phenylacetic acid,but also non-volatile dibutyl phthalate was detected in permeate water due to membrane wetting.FT-IR and SEM–EDS results indicated that the deposits formed on the membrane inner surface mainly consisted of Ca,Mg,and amine,carboxylic acid and aromatic groups.The fouled membrane could be recovered,as most of the deposits could be removed using a HCl/Na OH chemical cleaning method.     

Improved blending strategy for membrane modification by virtue of surface segregation using surface-tailored amphiphilic nanoparticles

Membrane modification is one of the most feasible and effective solutions to membrane fouling problem which tenaciously hampers the further augmentation of membrane separation technology. Blending modification with nanoparticles (NPs), owing to the convenience of being incorporated in established membrane production lines, possesses an advantageous viability in practical applications. However, the existing blending strategy suffers from a low utilization efficiency due to NP encasement by membrane matrix. The current study proposed an improved blending modification approach with amphiphilic NPs (aNPs), which were prepared through silanization using 3-(Trimethoxysilyl)propyl methacrylate (TMSPMA) as coupling agents and ZnO or SiO₂ as pristine NPs (pNPs), respectively. The Fourier transform infrared and X-ray photoelectron spectroscopy analyses revealed the presence of appropriate organic components in both the ZnO and SiO₂ aNPs, which verified the success of the silanization process. As compared with the pristine and conventional pNP-blended membranes, both the ZnO aNP-blended and SiO₂ aNP-blended membranes with proper silanization (100% and 200%w/w) achieved a significantly increased blending efficiency with more NPs scattering on the internal and external membrane surfaces under scanning electron microscope observation. This improvement contributed to the increase of membrane hydrophilicity. Nevertheless, an extra dosage of the TMSPMA led to an encasement of NPs, thereby adversely affecting the properties of the resultant membranes. On the basis of all the tests, 100% (w/w) was selected as the optimum TMSPMA dosage for blending modification for both the ZnO and SiO₂ types.

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Effects of bisphenol A on Gammarus fossarum and Lumbriculus variegatus in artificial indoor streams

The impact of bisphenol A (BPA) on Gammarus fossarum and Lumbriculus variegatus was studied in four artificial indoor streams (0, 5, 50 and 500?µg?L^?1 BPA, nominal) over 103 days in a pulse–dose exposure scenario (weekly BPA application). For G. fossarum populations at day 103, the proportions of juveniles and of breeding females from the highest BPA treatment were in tendency reduced. For individually exposed gammarid pairs an EC₁₀ of 17?µg?L^?1 BPA (nominal) for the proportion of reproductive females in the fourth brood was determined. During the first three broods, the largest brood size occurred at the highest BPA concentration, whereas in the fourth brood it decreased concentration-dependently (fourth brood EC₁₀?=?5?µg?L^?1 BPA, nominal). Effects on L. variegatus were a reduced population growth (103?d-EC₁₀ of 2?µg?L^?1 BPA, nominal) and an increase in dry weight and the number of segments in large, complete worms.     

Effect of iron addition on the performance of anoxic-oxic membrane process and biological phosphorus removal北大核心CSCD

In order to solve the problem of poor treatment of phosphorus in membrane bioreactor (MBR) with long sludge retention time (SRT), a ferric salt was added to enhance phosphorus removal; FeCl36H2O (Fe/P = 2.0) was added to the reactor. The removal efficiency of nitrogen, organic matters, and phosphorus in the MBR was investigated systematically. Moreover, this study focused on the membrane performance, the change of active sludge flora, and the effect of adding a ferric salt on membrane fouling before and after the addition. It was seen that adding the ferric salt could not affect the removal of COD and NH4 +-N and the removal rate of COD and NH4 +-N reached over 90%. However, the average removal rate of phosphorus was 52%, while the removal rate increased by nearly 40% after adding the ferric salt. The effects of adding ferric salts on the dominant bacteria and biological phosphorus removal of activated sludge were further studied. The results showed that the addition of ferric salt (Fe/P = 2.0) decreased the diversity of active sludge flora and relative abundance of some phosphorusaccumulating organisms and had a negative effect on biological phosphorus removal. The analysis of transmembrane pressure difference (TMP) recording revealed that the concentration of iron salts did not exacerbate membrane fouling. The results showed that the concentration of iron salts entering the membrane bioreactor would reduce the relative abundance and phosphorus removal efficiency of the activated sludge in the system to a certain extent, but it had no obvious effect on membrane fouling. It allowed the effluent to attain acceptable standards, especially with respect to phosphorus removal efficiency. © 2018 Science Press. All rights reserved.     

腈菌唑不同对映体对丽斑麻蜥性腺系统的影响

腈菌唑(myclobutanil,MT)是一种应用广泛的手性杀菌剂,其手性对映体为(+)-腈菌唑(MT1)和(-)-腈菌唑(MT2)。腈菌唑手性单体具有不同的生物活性,但很少有其对爬行动物的对应选择毒性研究。为了评估腈菌唑手性单体对丽斑麻蜴性腺系统的毒性影响,将MT1(50 mg·kg-1)和MT2(50 mg·kg-1)以经口灌胃方式分别暴露给蜥蜴28 d。暴露期间,记录观察蜥蜴体重、血液中性激素(睾酮T和雌二醇E2)浓度以及性腺相关基因(3β-HSD、17β-HSD、CYP11A、CYP17、CYP19A、ER-α和AR)的表达图谱的变化。在MT1暴露组中,蜥蜴体重在28 d出现明显下降。而在MT2暴露组中,蜥蜴体重没有明显变化。雄性蜥蜴在经过1 d的暴露后,E2浓度在MT1暴露组中明显下降,而在MT2暴露组中明显上升。这些结果表明了腈菌唑手性单体的对映选择性毒性。在MT2暴露14 d后,雌性蜥蜴中CYP19A基因的表达上调弥补了体内E2浓度的降低。在MT1暴露的14 d,蜥蜴卵巢中观察到的CYP11A和CYP17基因表达下调以及CYP19A基因表达不变的这一现象解释了蜥蜴血液中E2和T的浓度减少。这些结果表明:MT1和MT2暴露对蜥蜴体内性激素造成不同的影响,而这些影响会相应改变性腺相关基因的表达。综上所述,MT1和MT2对性腺系统具有潜在的内分泌干扰效应,可能对蜥蜴造成不同程度的生殖损伤。     

Comparison of membrane fouling in ultrafiltration of down-flow and up-flow biological activated carbon effluents

The UF membrane fouling by down- and up-flow BAC effluents were compared. Up-flow BAC effluent fouled the membrane faster than down-flow BAC effluent. The combined effects dominated irreversible fouling. The extent of fouling exacerbated by inorganic particles was higher. The TMP, permeate flux, and normalized membrane flux during 21 days of UF of DBAC and UBAC effluents. Fouling during ultrafiltration of down- and up-flow biological activated carbon effluents was investigated to determine the roles of polysaccharides, proteins, and inorganic particles in ultrafiltration membrane fouling. During ultrafiltration of down- flow biological activated carbon effluent, the trans-membrane pressure was≤26 kPa and the permeate flux was steady at 46.7 L?m⁻²?h⁻¹. However, during ultrafiltration of up-flow biological activated carbon effluent, the highest trans-membrane pressure was almost 40 kPa and the permeate flux continuously decreased to 30 L?m⁻²?h⁻¹. At the end of the filtration period, the normalized membrane fluxes were 0.88 and 0.62 for down- and up-flow biological activated carbon effluents, respectively. The membrane removed the turbidity and polysaccharides content by 47.4% and 30.2% in down- flow biological activated effluent and 82.5% and 22.4% in up-flow biological activated carbon effluent, respectively, but retained few proteins. The retention of polysaccharides was higher on the membrane that filtered the down- flow biological activated effluent compared with that on the membrane that filtered the up-flow biological activated carbon effluent. The polysaccharides on the membranes fouled by up-flow biological activated carbon and down- flow biological activated effluents were spread continuously and clustered, respectively. These demonstrated that the up-flow biological activated carbon effluent fouled the membrane faster. Membrane fouling was associated with a portion of the polysaccharides (not the proteins) and inorganic particles in the feed water. When there was little difference in the polysaccharide concentrations between the feed waters, the fouling extent was exacerbated more by inorganic particles than by polysaccharides.     

Energy reduction of a submerged membrane bioreactor using a polytetrafluoroethylene (PTFE) hollow-fiber membrane

The fiber length and packing density of the PTFE membrane element were increased. The MBR was stably operated under an SAD^m of 0.13 m³·m^-2·hr^-1. Specific energy consumption was estimated to be less than 0.4 kWh·m^-3. In this study, we modified a polytetrafluoroethylene (PTFE) hollow-fiber membrane element used for submerged membrane bioreactors (MBRs) to reduce the energy consumption during MBR processes. The high mechanical strength of the PTFE membrane made it possible to increase the effective length of the membrane fiber from 2 to 3 m. In addition, the packing density was increased by 20% by optimizing the membrane element configuration. These modifications improve the efficiency of membrane cleaning associated with aeration. The target of specific energy consumption was less than 0.4 kWh·m^-3 in this study. The continuous operation of a pilot MBR treating real municipal wastewater revealed that the MBR utilizing the modified membrane element can be stably operated under a specific air demand per membrane surface area (SAD_m) of 0.13 m³·m^-2·hr^-1 when the daily-averaged membrane fluxes for the constant flow rate and flow rate fluctuating modes of operation were set to 0.6 and 0.5 m³·m^-2·d^-1, respectively. The specific energy consumption under these operating conditions was estimated to be less than 0.37 kWh·m^-3. These results strongly suggest that operating an MBR equipped with the modified membrane element with a specific energy consumption of less than 0.4 kWh·m^-3 is highly possible.     

Nonylphenol in the environment: a critical review on occurrence, fate, toxicity and treatment in wastewaters

Nonylphenol is a toxic xenobiotic compound classified as an endocrine disrupter capable of interfering with the hormonal system of numerous organisms. It originates principally from the degradation of nonylphenol ethoxylates which are widely used as industrial surfactants. Nonylphenol ethoxylates reach sewage treatment works in substantial quantities where they biodegrade into several by-products including nonylphenol. Due to its physical-chemical characteristics, such as low solubility and high hydrophobicity, nonylphenol accumulates in environmental compartments that are characterised by high organic content, typically sewage sludge and river sediments, where it persists. The occurrence of nonylphenol in the environment is clearly correlated with anthropogenic activities such as wastewater treatment, landfilling and sewage sludge recycling. Nonylphenol is found often in matrices such as sewage sludge, effluents from sewage treatment works, river water and sediments, soil and groundwater. The impacts of nonylphenol in the environment include feminization of aquatic organisms, decrease in male fertility and the survival of juveniles at concentrations as low as 8.2 mug/l. Due to the harmful effects of the degradation products of nonylphenol ethoxylates in the environment, the use and production of such compounds have been banned in EU countries and strictly monitored in many other countries such as Canada and Japan. Although it has been shown that the concentration of nonylphenol in the environment is decreasing, it is still found at concentrations of 4.1 mug/l in river waters and 1 mg/kg in sediments. Nonylphenol has been referred to in the list of priority substances in the Water Frame Directive and in the 3rd draft Working Document on Sludge of the EU. Consequently there is currently a concern within some industries about the possibility of future regulations that may impose the removal of trace contaminants from contaminated effluents. The significance of upgrading sewage treatment works with advanced treatment technologies for removal of trace contaminants is discussed.