A novel approach to estimate and control denitrification performance in activated sludge systems with respirogram technology

Respirogram technology has been widely applied for aerobic process, however, the response of respirogram to anoxic denitrification is still unclear. To reveal such response may help to design a new method for the evaluation of the performance of denitrification. The size distribution of flocs measured at different denitrification moments demonstrated a clear expansion of flocs triggered by denitrification, during which higher specific endogenous and quasi-endogenous respiration rates (SOUR_e and SOUR_q) were also observed. Furthermore, SOUR_q increases exponentially with the specific denitrification rate (SDNR), suggesting that there should be a maximum SDNR in conventional activated sludge systems. Based on these findings, an index R_q/t, defined as the ratio of quasi-endogenous (OUR_q) to maximum respiration rate (OUR_t), is proposed to estimate the denitrification capacity that higher R_q/t indicates higher denitrification potential, which can be readily obtained without complex measurement or analysis, and it offers a novel and promising respirogram-based approach for denitrification estimation and control by taking measures to extend anoxic time to maintain its value at a high level within a certain range.     

Roles of semivolatile and intermediate-volatility organic compounds in secondary organic aerosol formation and its implication: A review

Secondary organic aerosol(SOA) is a very important component of fine particulate matter(PM_2.5) in the atmosphere. However, the simulations of SOA, which could help to elucidate the detailed mechanism of SOA formation and quantify the roles of various precursors, remains unsatisfactory, as SOA levels are frequently underestimated. It has been found that the performance of SOA formation models can be significantly improved by incorporating the emission and evolution of semivolatile and ...     

城市建筑废弃物的科学管理与有效利用研究

在城镇化建设进程中,经济快速发展和建设过程中产生的建筑垃圾是同时并存的.作为可回收利用资源的建筑废弃物,通过有效利用可转化成可观的经济效益;若对于建筑废弃物未科学回用,不仅会造成资源浪费,还会引起生态系统破坏.通过了解国内外建筑废弃物现状,阐述建筑废弃物处理手段,分析建筑再生材料的市场应用前景.进而对国内建筑垃圾管理和利用提出相关建议和展望,为建筑废弃物环境管理和资源化利用提供理论依据和支持.     

Reference gene validation for quantification of gene expression during final oocyte maturation induced by diethylstilbestrol and di-(2-ethylhexyl)-phthalate in common carp

Final oocyte maturation is the key step to successful spawning and fertilization.Quantitative real-time PCR(q PCR) is the technique of election to quantify the abundance of functional genes in such study. Reference gene is essential for correct interpretation of q PCR data. However, an ideal universal reference gene that is stable under all experimental circumstances has not been described. Researchers should validate their reference genes while performing q PCR analysis. The expression of 6 candidate reference genes: 18 s r RNA,28 s r RNA, Cathepsin Z, Elongation factor 1-α, Glyceraldehyde-3-phosphate dehydrogenase andβ-actin were investigated during final oocyte maturation induced by different compounds(DES and DEHP) in common carp(Cyprinus carpio). Four softwares(Bestkeeper, ge Norm,Norm Finder and Ref Finder) were used to screen the most stable gene in order to evaluate their expression stability. The results revealed that EF1α was highly stable expressed when final oocyte maturation was induced by DES, while gapdh was the most stable gene when final oocyte maturation was induced by DEHP. Stable expressed reference gene selection is critical for all q PCR analysis to get accurate target gene m RNA expression information.     

再生水中的Pb对萝卜根际土壤微生物群落结构的影响研究

采用盆栽方法研究再生水、再生水+Pb、清水+Pb处理浇灌萝卜,以清水浇灌为对照对萝卜根际土壤微生物群落的影响进行研究。结果表明:(1)土壤总PLFA含量及各菌群生物量从大到小依次为:再生水再生水+Pb清水清水+Pb。再生水灌溉有利于萝卜根际微生物各类群数量的增加,丰富微生物多样性。用含铅的溶液(再生水+Pb、清水+Pb)浇灌萝卜,可抑制土壤微生物各类群的数量,G-受到的抑制尤为明显。(2)主成分分析表明,再生水灌溉与对照相比,土壤微生物群落结构差异最大。(3)土壤微生物各类群与土壤速效钾、硝酸盐氮含量呈极显著正相关(P0.01),真菌、放线菌与土壤有机质含量,G~+、G~-菌与p H均呈极显著正相关(P0.01)。G~+、G~-与萝卜地下鲜重均呈极显著负相关(P0.01),土壤微生物各类群与地上部分硝酸盐含量、与根冠比呈极显著正相关(P0.01)。     

环境监测仪器的有效管理

对本文结合实际工作,从仪器建档、日常维护使用、人员职责等方面进行阐述,总结出一套具有可操作性的环境监测仪器管理程序。     

论"水十条"对中国水体污染防治的意义

2015年4月16日,国务院正式发布《水污染防治行动计划》,《水污染防治行动计划》为了与一年前出台的"大气十条"相对应,故亦简称"水十条".这将是今后很长一段时期中国治理水环境的纲领性文件."水十条"对中国水污染治理工作提出了总体目标,同时作为新环保法的延伸,"水十条"将强调市场机制在治理水体污染中的作用、促进环境需求的多样化.总的来说,"水十条"的发布,标志着中国将对水污染防控治理进行强力监管,铁腕治污将进入"新常态".     

河北省PM2.5污染变化特征及暴露人群健康效应评估研究

PM2.5污染是影响中国城市居民健康和形成雾霾天气的重要原因之一,也是河北省健康发展的一个制约因素.采用环境污染流行病研究为基础的暴露-反应关系估算了2014年和2015年全省因PM2.5污染的居民早逝和罹患相关疾病住院的人数,并利用国家和河北省卫生统计数据,估算出人均人力资源价值和人均住院成本,计算出总经济损失.结果表明,河北省各市的PM2.5年均浓度呈下降趋势,因此,继续坚持有效的大气污染控制和应急健康防护措施,仍然是今后环保工作的重中之重.     

Numerical evaluation of the effectiveness of NO2 and N2O5 generation during the NO ozonation process

Wet scrubbing combined with ozone oxidation has become a promising technology for simultaneous removal of SO₂ and NO_x in exhaust gas. In this paper, a new 20-species, 76-step detailed kinetic mechanism was proposed between O₃ and NO_x. The concentration of N₂O₅ was measured using an in-situ IR spectrometer. The numerical evaluation results kept good pace with both the public experiment results and our experiment results. Key reaction parameters for the generation of NO₂ and N₂O₅ during the NO ozonation process were investigated by a numerical simulation method. The effect of temperature on producing NO₂ was found to be negligible. To produce NO₂, the optimal residence time was 1.25 sec and the molar ratio of O₃/NO about 1. For the generation of N₂O₅, the residence time should be about 8 sec while the temperature of the exhaust gas should be strictly controlled and the molar ratio of O₃/NO about 1.75. This study provided detailed investigations on the reaction parameters of ozonation of NO_x by a numerical simulation method, and the results obtained should be helpful for the design and optimization of ozone oxidation combined with the wet flue gas desulfurization methods (WFGD) method for the removal of NO_x.     

In vitro evaluation of inorganic and methyl mercury mediated cytotoxic effect on neural cells derived from different animal species

To extend the current understanding of the mercury-mediated cytotoxic effect,five neural cell lines established from different animal species were comparatively analyzed using three different endpoint bioassays:thiazolyl blue tetrazolium bromide,3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay(MTT),neutral red uptake assay(NRU),and Coomassie blue assay(CB).Following a 24-hr exposure to selected concentrations of mercury chloride(HgCl_2) and methylmercury(Ⅱ) chloride(MeHgCl),the cytotoxic effect on test cells was characterized by comparing their 50%inhibition concentration(IC_(50)) values.Experimental results indicated that both these forms of mercury were toxic to all the neural cells,but at very different degrees.The IC_(50)values of MeHgCl among these cell lines ranged from 1.15±0.22 to 10.31 ± 0.70 μmol/L while the IC_(50) values for HgCl_2 were much higher,ranging from 6.44 ± 0.36 to 160.97±19.63 μmol/L,indicating the more toxic nature of MeHgCl.The IC_(50) ratio between HgCl_2and MeHgCl ranged from 1.75 to 96.0,which confirms that organic mercury is much more toxic to these neural cells than inorganic mercury.Among these cell lines,HGST-BR and TriG44 derived from marine sea turtles showed a significantly high tolerance to HgCl_2 as compared to the three mammalian neural cells.Among these neural cells,SK-N-SH represented the most sensitive cells to both chemical forms of mercury.