改性粉煤灰混凝剂处理工业混合废水的试验研究

通过混合酸、氯化钠制备改性粉煤灰混凝剂,探讨粉煤灰粒度、酸用量、加热时间、反应温度等对废水处理效果的影响,得出制备混凝剂最佳工艺方案。通过正交试验,用最佳混凝剂处理工业混合废水,找出混凝剂投量、废水pH值、搅拌时间及静置时间等最佳参数,探索一条以废治废的可行方法。     

Take your swimsuit along: the value of improving urban bathing sites in the metropolitan area of Berlin

Many inhabitants of Berlin enjoy bathing in lakes and rivers during the summer. However, so far no data exist about who goes bathing and what quality bathers expect from bathing sites. In an online survey conducted during the summer of 2007 respondents were presented with a choice experiment concerning various attributes of bathing sites such as water quality or cleanliness of the beach. Applying both random parameter logit models as well as a latent class model reveals that unobserved taste heterogeneity is present among bathers, i.e. not all bathers would benefit equally from improving bathing sites. A test concerning preference consistency reveals high internal validity.     

Regional NOx emission inversion through a four-dimensional variational approach using SCIAMACHY tropospheric NO2 column observations

In this paper, the NOx emission scaling factors applied over the 2001 National Emissions Inventory (NEI) are estimated through a four-dimensional variational (4D-Var) approach using SCIAMACHY (Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY) tropospheric NO₂ columns measured during summer 2004. In the “top-down” approach, two-month average NO₂ columns are assimilated into a regional chemical transport model (CTM), STEM, using different assimilation setups. In a basic setup, NOx emissions are adjusted by assimilating the NO₂ columns. A more general setup of emission inversion allows the initial O₃ concentrations be adjusted along with the NOx emissions. A final case is set up to assimilate both the NO₂ columns and O₃ measurement from various platforms while allowing adjustments of both the NOx emissions and the initial O₃ concentrations. It is found that the addition of O₃ measurements did not improve the NOx emission inversion. With the NOx emission at surface and upper levels being adjusted separately, results from four cases show that the elevated NOx emission reduction ranges from 8.9% to 11.4%, and the surface NOx emission reduction is up to 6.6%. All the cases show NOx emission reduction in Ohio valley and Washington, District of Columbia areas.     

应变率效应对钢筋混凝土柱的影响

根据混凝土单轴动力特性试验,引入了应变率的影响,对规范给出的混凝土应力—应变关系表达式进行了修正;针对只考虑混凝土的动态特性和既考虑混凝土的动态特性、也考虑钢筋的动态特性这两种情况,利用修正的表达式对钢筋混凝土柱的动态特性进行了数值分析。结果表明,混凝土的动态特性对于大偏心柱的承载力影响很小,但对于小偏心柱的极限承载力影响显著;钢筋的动态特性对大、小偏心柱的极限弯矩和极限曲率都有明显的影响。本文还分析了柱的极限弯矩、极限曲率和极限轴力随偏心距变化的规律。     

Assessing visitor satisfaction with tourism rejuvenation policies: the case of Rimini,Italy

This paper assesses the appeal of potential interventions on the tourism offer of Rimini, a popular Italian seaside holiday destination, by means of a choice modelling analysis. Tourism can be viewed as a composite good, its overall utility depending on the arrangement of the component characteristics. The discrete choice experiments here incorporate as attributes a number of possible changes to current tourist activities (the subject of public debate), including them in hypothetical alternative holiday packages. The conditional logit analysis indicates that tourists show lesser preference for interventions aimed at protecting the environmental integrity of the beach and greater preference for those, such as the creation of a pedestrianised seafront with late-night opening of amenities and facilities, that are likely to diminish the role of the traditional sea, sun and sand component of the overall holiday experience.     

TiO_2/活性炭光催化技术在印染废水深度处理中的应用研究

通过TiO2／活性炭光催化剂的光催化氧化作用,对印染废水的生化处理出水进行深度处理。实验考察了pH值、催化剂负载次数、光照时间、催化剂投加量等因素对处理效果的影响。实验结果表明：催化剂负载次数为4次,光照时间30min,催化剂投加量为3g时,处理效果最佳。此时出水COD达到50mg／L,色度为2,达到印染行业回用水的标准。     

混凝法处理有机氯农药废水的研究

以有机氯农药废水为研究对象 ,研究了无机混凝剂PAC及其与有机高分子混凝剂PAM (J 3450 ,J 1 1 50 )复合使用的混凝处理特性。通过正交实验确定了混凝反应各种影响因子的最佳操作条件。在此条件下 ,水质 1、2的COD去除率分别为 38%、40 .6 % ;色度去除率分别为 98% ,2 0 %。混凝处理后 2种水质的B/C值也得到了提高。在各影响因子与COD去除率的关系曲线基础上 ,分析了废水中各影响因子的作用机理。     

有机碳含量对多环芳烃在土壤剖面残留及迁移的影响

为了揭示有机碳含量(TOC)对多环芳烃(PAHs)在土壤剖面中迁移的影响,本文分析了北京地区部分典型的环境功能区(包括自然保护区、耕地、果园、农田、城区及工业区等)土壤剖面中多环芳烃和TOC的纵向分布特征,结合多环芳烃化合物的土柱淋滤实验,讨论了多环芳烃在土壤剖面上的纵向迁移特征.结果表明,不同环境功能区土壤剖面的土壤中多环芳烃的含量存在差异,且与TOC之间存在较强的正相关关系;土柱淋滤实验结果进一步证实,尽管具有不同TOC的土壤剖面中多环芳烃均可能向深层迁移,但TOC对土壤剖面中多环芳烃的残留及纵向迁移能力具有重要的影响,TOC越高,多环芳烃富集量越大,向下迁移量相对减少,反之相反;在TOC相同的情况下,多环芳烃的组成或结构特征对其在土壤剖面中的残留与迁移特征有明显的影响,淋滤水量、淋滤时间和添加PAHs量等对其在土壤剖面中的迁移作用也有一定影响.     

Kinetics of phenol and m-cresol biodegradation by an indigenous mixed microbial culture isolated from a sewage treatment plant

An acclimatized mixed microbial culture, predominantly Pseudomonas sp., was enriched from a sewage treatment plant, and its potential to simultaneously degrade mixtures of phenol and m-cresol was investigated during its growth in batch shake flasks. A 2² full factorial design with the two substrates at two different levels and different initial concentration ranges (low and high), was employed to carry out the biodegradation experiments. The substrates phenol and m-cresol were completely utilized within 21 h when present at low concentrations of 100 mg/L for each, and at high concentration of 600 mg/L for each, a maximum time of 187 h was observed for their removal. The biodegradation results also showed that the presence of phenol in low concentration range (100–300 mg/L) did not inhibit m-cresol biodegradation. Whereas the presence of m-cresol inhibited phenol biodegradation by the culture. Moreover, irrespective of the concentrations used, phenol was degraded preferentially and earlier than m-cresol. A sum kinetics model was used to describe the variation in the substrate specific degradation rates, which gave a high coefficient of determination value (R² > 0.98) at the low concentration range of the substrates. From the estimated interaction parameter values obtained from this model, the inhibitory effect of phenol on m-cresol degradation by the culture was found to be more pronounced compared to that of m-cresol on phenol. This study showed a good potential of the indigenous mixed culture in degrading mixed substrate of phenolics.     

Kinetics of phenol and m-cresol biodegradation by an indigenous mixed microbial culture isolated from a sewage treatment plant

An acclimatized mixed microbial culture, predominantly Pseudomonas sp., was enriched from a sewage treatment plant, and its potential to simultaneously degrade mixtures of phenol and m-cresol was investigated during its growth in batch shake flasks. A 22 full factorial design with the two substrates at two di erent levels and di erent initial concentration ranges (low and high), was employed to carry out the biodegradation experiments. The substrates phenol and m-cresol were completely utilized within 21 h when present at low concentrations of 100 mg/L for each, and at high concentration of 600 mg/L for each, a maximum time of 187 h was observed for their removal. The biodegradation results also showed that the presence of phenol in low concentration range (100–300 mg/L) did not inhibit m-cresol biodegradation. Whereas the presence of m-cresol inhibited phenol biodegradation by the culture. Moreover, irrespective of the concentrations used, phenol was degraded preferentially and earlier than m-cresol. A sum kinetics model was used to describe the variation in the substrate specific degradation rates, which gave a high coe cient of determination value (R2 > 0.98) at the low concentration range of the substrates. From the estimated interaction parameter values obtained from this model, the inhibitory e ect of phenol on m-cresol degradation by the culture was found to be more pronounced compared to that of m-cresol on phenol. This study showed a good potential of the indigenous mixed culture in degrading mixed substrate of phenolics.