Journal of Polymers and the Environment - Poor interfacial compatibility between wheat straw and polylactic acid (PLA) remains a problem that directly affects the overall performance of wheat... 相似文献
Trimethylolpropane (TMP) wastewater is one of the most toxic petrochemical wastewater. Toxicants with high concentrations in TMP wastewater often inhibit the activity of microorganisms associated with biological treatment processes. The hydrolysis acidification process (HAP) is widely used to pretreat petrochemical wastewater. However, the effects of HAP on the reduction of wastewater toxicity and the relevant underlying mechanisms have rarely been reported. In this study, an HAP reactor was operated for 240 days, fed with actual TMP wastewater diluted by tap water in varying ratios. The toxicity of TMP wastewater was assessed with the inhibition ratio of oxygen uptake rate. When the organic loading rates were lower than 7.5 kg COD/m3/d, the toxicity of TMP wastewater was completely eliminated. When the actual TMP wastewater was directly fed into the reactor, the toxicity of TMP wastewater decreased from 100% to 34.9%. According to the results of gas chromatographymass spectrometry analysis, four main toxicants contained in TMP wastewater, namely, formaldehyde, 2-ethylacrolein, TMP and 2-ethylhexanol, were all significantly removed, with removal efficiencies of 93.42%, 95.42%, 72.85% and 98.94%, respectively. Compared with the removal efficiency of CODCr, the reduction rate of toxicity is markedly higher by HAP. In addition, the change of microbial community in the HAP reactor, along the operation period, was studied. The results revealed that, compared with the seed sludge, Firmicutes became the dominant phylum (abundance increased from 0.51% to 57.08%), followed by Proteobacteria and Bacteroidetes (abundance increased from 59.75% to 25.99% and from 4.70% to 8.39%, respectively).
It is reported that the most abundant polycyclic aromatic hydrocarbons (PAHs) in weathered crude oils are cardiotoxic. However, the action mechanism of PAHs on vertebrate cardiovascular development and disease is unclear. In the present study, the cardiac morphology and functioning of zebrafish embryos exposed to benzo[a]pyrene [B(a)P], as a high-ring PAHs, for 72 h were observed and determined. The results showed that B(a)P exposure resulted in cardiac developmental defects in zebrafish embryos. Significant changes in expression level of multiple genes potentially critical for regulating the B(a)P-induced cardiovascular developmental defects were also found. A gene network regulating cardiac development perturbed by B(a)P exposure was identified and established by computational analysis and employment of some databases. The information from the network could provide a clue for further mechanistic studies explaining molecular events regulating B(a)P-mediated cardiovascular defects and consequences. 相似文献
The concept of temperature staged and biological phased (TSBP) was proposed to enhance the performance of waste-activated sludge anaerobic digestion. Semi-continuous experiments were used to investigate the effect of temperature (35 to 70℃) as well as the hydraulic retention time (HRT) (2, 4 and 6 days) on the acidogenic phase. The results showed that the solubilization degree of waste- activated sludge increased from 14.7% to 30.1% with temperature increasing from 35 to 70℃, while the acidification degree was highest at 45℃ (17.6%), and this was quite different from the temperature impact on hydrolysis. Compared with HRT of 2 and 6 days, 4 days was chosen as the appropriate HRT because of its relatively high solubilization degree (24.6%) and acidification degree (20.1%) at 45℃. The TSBP system combined the acidogenic reactor (45℃, 4 days) with the methanogenic reactor (35℃, 16 days) and the results showed 84.8% and 11.4% higher methane yield and volatile solid reduction, respectively, compared with that of the single-stage anaerobic digestion system with HRT of 20 days at 35℃. Moreover, different microbial morphologies were observed in the acidogenic- and methanogenic-phase reactors, which resulted from the temperature control and HRT adjustment. All the above results indicated that 45℃ was the optimum temperature to inhibit the activity of methanogenic bacteria in the acidogenic phase, and temperature staging and phase separation was thus accomplished. The advantages of the TSBP process were also confirmed by a full-scale waste-activated sludge anaerobic digestion project which was an energy self-sufficient system. 相似文献
In order to characterize environmental vanadium distribution, mobility, and bioaccumulation, a total of 55 soil samples and 36 plant samples were collected in four typical land-use districts in Panzhihua region, Southwestern China. Soil samples were analyzed with the modified Community Bureau of Reference (BCR) sequential extraction procedure, and the content of vanadium in soil and plant was determined by ICP-AES. The total content of vanadium was 208.1?C938.4 mg kg???1 in smelting area, 111.6?C591.2 mg kg???1 in mining area, 94.0?C183.6 mg kg???1 in urban park, and 71.7?C227.2 mg kg???1 in agricultural area, respectively, while the bio-available content of vanadium was characterized that the polluted areas (mining area 18.8?C83.6 mg kg???1, smelting area 41.7?C132.1 mg kg???1) and the unpolluted area (agricultural area 9.8?C26.4 mg kg???1, urban park 9.9?C25.2 mg kg???1). In addition, the contamination degree of vanadium in soil was smelting area > mining area > agricultural area ?? urban park. Moreover, the fraction of vanadium in each sequential extraction characterized that residual fraction > oxidizable fraction > reducible fraction > acid soluble fraction. The bioaccumulation of vanadium from soil to plant was weak to intermediate absorption. Therefore, some countermeasures such as soil monitoring and remediation should be to take in the sooner future, especially in mining and smelting area. 相似文献