投加阳离子聚合物加速UASB反应器中颗粒污泥形成

运行2个UASB反应器,研究常温低浓度进水条件下,投加阳离子季胺盐絮凝剂对厌氧颗粒污泥形成的影响。一个反应器中投加阳离子季胺盐絮凝剂（称A反应器）,另一个反应器作为对照不投加絮凝剂（称B反应器）。经过196 d的运行,2个反应器中均形成了活性较高、沉降性能良好的颗粒污泥。A反应器中的污泥颗粒更多、粒径更大,粒径＞0.5 mm的污泥颗粒的百分比比B反应器的多16%～19.3%。研究结果表明,投加阳离子聚合物加速了颗粒污泥的形成,提高了颗粒污泥的产甲烷活性和沉降性能。     

序批式生物膜反应器和序批式反应器处理硝酸盐氮污染河水

在序批式反应器(SBR)中添加ZH组合填料构成序批式生物膜反应器(SBBR),并以SBR为对比,研究了2种工艺对污染河水中硝酸盐氮的去除效果。结果表明,(1)进水硝酸盐氮浓度分别为15、20和30 mg/L时,2种工艺对COD的去除率均大于90%,对COD的去除能力均较强,进水硝酸盐氮的增加对COD的去除效果影响不大;第1个缺氧段是COD的主要去除段,此阶段COD的去除率达到80%以上。(2)随进水硝酸盐氮浓度的增加,SBBR中NO-3-N和TN的去除率分别从99.73%和99.24%降至79.75%和65.56%;SBR中NO-3-N和TN的去除率分别从99.91%和99.51%降至55.57%和41.73%。(3)随进水硝酸盐氮浓度的提高,两反应器内亚硝酸盐氮的积累量增大;进水硝酸盐氮浓度为15、20和30 mg/L时,SBBR中的亚硝酸盐氮最大积累浓度分别为2.90、6.82和10.72 mg/L;SBR中亚硝酸盐氮最大积累浓度分别为4.35、9.47和11.89 mg/L。SBBR中亚硝酸盐氮的积累明显低于SBR。     

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in breast milk from the Pacific Northwest

Breast milk samples from 40 first-time mothers from the Pacific Northwest of the US and Canada were analyzed for polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs). Total PBDEs (summation operator PBDEs), calculated by summing values for the 12 PBDEs congeners analyzed, ranged from 6 to 321 ppb (lipid weight) (mean=96 ppb; median=50 ppb). In approximately 40% of the women (15/40), summation operator PBDEs>100 ppb lw in their milk, and four samples had levels >250 ppb lw. PBDE 47 was the dominant congener in most samples, whereas PBDE 153 was predominant in a few (3/40). summation operator PCBs were calculated by summing values for the 82 PCB congeners analyzed, and ranged from 49 to 415 ppb (lipid weight) (mean=147 ppb; median=126 ppb). approximately 30% of the mothers (13/40) have summation operator PBDEs> summation operator PCBs in their milk samples, and approximately 65% (25/40) have BDE 47>PCB 153 in breast milk samples, with BDE 47 averaging 3-fold greater levels than PCB 153. Clearly, the lower brominated PBDEs are surpassing PCBs as a major environmental concern in North America, and are likely affecting significant portions of the populations in these regions. PBDEs have become a major persistent organic pollutant. However, there are no positive correlations between levels of summation operator PBDEs and summation operator PCBs, or between levels of PBDE 47 and PCB 153, suggesting there may be some differences in exposure pathways for PBDEs and PCBs in humans.     

废水中硝基酚类化合物生物降解的研究进展

硝基酚是一类重要且常用的化工原料,一些硝基酚毒性大且难以生物降解,被美国环保局列入“优先控制污染物名单”。在自然环境条件下,硝基酚的生物降解速率缓慢,导致硝基酚在环境中长期滞留和积累。分析了人工强化条件下废水中硝基酚的生物降解性能,主要从具有降解硝基酚能力的微生物、硝基酚的厌氧生物降解性、硝基酚的好氧生物降解性和硝基酚的共基质代谢降解方面进行了较全面的综述,讨论了该研究当前仍存在的一些问题和研究展望。     

Effectiveness of cascading time series models based on meteorological factors in improving health risk prediction

Environmental Science and Pollution Research - Meteorological factors, which are periodic and regular in a long run, have an unignorable impact on human health. Accurate health risk prediction...