Biodegradation of persistent polar pollutants in wastewater: comparison of an optimised lab-scale membrane bioreactor and activated sludge treatment

The biodegradation of selected non-adsorbing persistent polar pollutants (P(3)) during wastewater (WW) treatment was studied by comparing a lab-scale membrane bioreactor (MBR) running in parallel to activated sludge treatment (AST). The investigated P(3) are relevant representatives or metabolites from the compound classes: pesticides, pharmaceuticals, insect repellents, flame retardants and anionic surfactants. Analyses of all these P(3) at low ng L(-1) levels with sufficient standard deviations was performed in WW influents and effluents. Non-degradable micropollutants, such as EDTA and carbamazepine were not eliminated at all during WW treatment by any technique. However, the MBR showed significant better removals compared to AST for the investigated poorly biodegradable P(3), such as diclofenac, mecoprop and sulfophenylcarboxylates. An application of such an in terms of sludge retention time optimised MBR may lead to a reduction of these P(3) in the watercycle.     

Influence of limestone filler and viscosity-modifying admixture on the porous structure of self-compacting concrete

The objective of this experimental work is to study porosity in self-compacting concrete (SCC) made without adding limestone filler, comparing the results with other SCC and with normally-vibrated concrete (NVC). Several types of concrete were made, keeping the w/c ratio constant. The results show that the air content in SCC depends on the flowability and viscosity of the material, putting a forward an expression to estimate the air content in accordance with these two parameters. SCC shows a finer and more tortuous porous structure than NVC, leading to lower permeability to water under pressure. Nevertheless, in the absence of pressure, when water penetrates by capillary action, the results obtained from the different types of concrete were very similar, with differences below 3.5%. This is due to the fact that the content of pores over 0.5 μm is practically the same in SCC and NVC, but for smaller pore sizes, which are therefore only accessed when water under pressure is applied, the differences in porosity between the different samples is more pronounced. On the other hand, it was observed that the use of more fluid mixtures permitted more impermeable concrete to be obtained. The use of viscosity-modifying admixture on SCC as a replacement for limestone filler does not affect the total volume of pores, but generates a slightly more coarse porous microstructure, thereby leading to concretes in which water penetration depth under pressure is a little higher (around 4 mm).     

A graphical method of presenting property rights,building types,and residential behaviors: A case study of Xiaoxihu historic area,Nanjing

One of the main reasons for the decline of urban historic areas in China is the co-existence of multiple property rights. It also deeply affects conservation and regeneration practice. This paper aims to propose a graphical method that illustrates the association between property rights, space, and resident behavior. Based on typological maps and justified graphs, a three-step method was proposed to visualize the relationships between these three elements. The final graph and quantitative data were used to observe the evolution of the courtyard building from a diachronic perspective, as well as to compare the residential behavior in different types from a synchronic perspective. The results show that following the subdivision of property rights, the building layout become more diverse due to various illegal additions, while the residential behavior within different building types tends to be consistent. Moreover, the study observed the traditional Chinese courtyard buildings’ adaptability. The findings contribute to understand the evolution of Chinese urban historic areas and internal motivation, and provide guidance for the conservation and regeneration practice.     

Buckling strength verification of cantilevered cylindrical shells subjected to transverse load using Eurocode 3

At present, there are only a few studies concerning the application of different types of buckling strength verification according to Eurocode 3 at combined loading. Besides the stress design as classical hand calculation method of checking cylindrical steel shells against buckling failure, the new Eurocode 3 also offers two global numerical analyses at different modelling levels. The linear buckling analysis (LBA) combined with a materially nonlinear but geometrically linear analysis (MNA) is the simpler concept from the perspective of the modelling and calculation effort. The more sophisticated method is a geometrically and materially nonlinear analysis of the imperfect structure (GMNIA). This paper presents the application of both numerical concepts to the cantilevered shell subject to a transverse load at the free edge. The results are compared to those from stress design. There are specific features at both types of numerical analysis: As the determination of the plastic reference resistance and the buckling parameters is the main focus at MNA/LBA, the choice of proper equivalent geometric imperfections demands special diligence at GMNIA. The presented analyses show that the GMNIA concept in connection with consistent equivalent geometric imperfections may lead to a safe and economic design of cylinders subject to combined loading. At the particular load case the MNA/LBA concept currently suffers from the lack of proper regulations concerning the determination of the overall buckling reduction factor.     

Meteorological and oceanographic conditions in the northern Adriatic Sea during the period June 1999-July 2002: influence on the mucilage phenomenon

Mucilage events (formation of very large organic aggregates and gelatinous surface layers) have been documented several times during the past two centuries in the northern Adriatic Sea (NA), while their frequency has significantly increased since 1988. In this work, meteorological and oceanographic conditions in the NA during the period June 1999-July 2002 are described and their relation to the outbreak and fate of the mucilage phenomenon was investigated. Salinity and temperature data were collected during approximately monthly cruises along three transects in the NA. Relevant meteorological situations (air temperature, rainfall, wind) were selected from large-scale ECMWF analyses and from the Local Analysis and Prediction System (LAPS; Emilia Romagna Meteorological Service), while sea conditions (waves) were analysed by means of the Wave Adriatic Model (WAM). Data for air temperature, rainfall, and wind from several meteorological stations in the region were used. Average seasonal cycles of sea temperature and salinity simulated with statistical models, based on historical data collected in the NA since 1972, were used to determine thermal and haline anomalies. The monthly anomaly variability of maximum and minimum air temperatures, rainfall amount and number of rainy days did not appear to be relevant for the mucilage phenomenon outbreak. In contrast, both vertical and horizontal thermohaline gradients in the region were more developed during late spring and summer of 2000 and particularly of 2002, when the mucilage events were of greatest extent in space and time, compared to 2001 (short-lived event) and 1999 (no event). These more pronounced gradients were due to a combination of several unusual conditions: sharp heating of the sea surface in May-June, domination of eastwards transport of freshened waters formed in the Po Delta area, and intrusion of very high salinity intermediate waters originating in the eastern Mediterranean. Moreover, in winter of both 2000 and 2002 very dense and cold water formed and remained in the bottom layer until spring, contributing to increase the stratification degree of the water column. The duration of the mucilage events and their spatial distribution in the region depend strongly on meteorological changes. Recurrent anticyclonic conditions, characterized by low wind and calm sea, favour extended events in time (up 2 months in 2002). In contrast, highly perturbed weather, particularly due to strong "bora" wind, can be determined in sharp decay of the event (e.g. in July 2000).     

Banking structure and regional economic growth: lessons from Italy

Following the literature on the comparative advantage of small versus large banks at lending to small businesses and in light of the worldwide decline in the number of intermediaries that specialise in this type of lending associated with deregulation in the banking industry, we examine the role that specific categories of banks have played in the context of Italy’s regional economic growth. Over the estimation period, 1970–1993, which ends in the year of full implementation of the banking reform that introduced statutory de-specialisation and branching liberalisation, Italy featured not only a substantial presence of small- and medium-sized enterprises (SMEs) in the real sector, as is still the case, but also a large and heterogeneous set of credit institutions with different ownership, size and lending styles. Exploiting these peculiarities we study the role of specific intermediaries and gather indirect evidence concerning the likely effects, ceteris paribus, of the current consolidation processes. The main findings, stemming from panel regressions with fixed effects, are as follows. The overall size of the financial sector has a weak impact on growth, but some intermediaries are better than others: cooperative banks and special credit institutions play a positive role, banks of national interest (basically large private banks) and public law banks (government-owned banks) either do not affect growth or have a negative influence depending on how growth is measured. Cooperative banks were mostly small banks and special credit institutions were all but large conglomerates with standardized credit policies, hence our results lend support to the current worldwide concerns of a reduction in the availability of credit to SMEs resulting from consolidation and regulatory reforms in the banking industry.

Dealing with living in poor neighbourhoods

In this prologue to the special issue, the guest editors place the contributions in the context of current debates on living in concentrated poverty neighbourhoods. These debates concern two broad categories of residents: poor households that are assisted to move from concentrations of poverty to lower-poverty areas (movers); and households (not exclusively the poor) that cannot move out of poor neighbourhoods or are not willing to do so, for various reasons (stayers). For the first category, the main issue is whether housing vouchers provide movers only with better housing or also with other social, psychological and economic benefits. A wealth of (partly contradictory) evidence justifies exploring a fundamental question: What should housing vouchers do? With regard to those unwilling or unable to move out of poor neighbourhoods, we focus on how residents cope with the recurrent problems and stressful circumstances in poor neighbourhoods. Here, four interrelated concepts are central to our discussion: place attachment, coping tactics, territoriality, and social network formation. Our discussion paves the way for the subsequent five papers, each dealing with one of the selected topics. The aim of this special issue is to provide new evidence that underpins or questions the current debates on living in or leaving neighbourhoods with concentrated poverty. The research reported here was done in the United States, Great Britain and the Netherlands.     

世博会英国馆裙房大悬挑折板结构设计与分析

世博会英国馆周边裙房的钢筋混凝土异形结构给结构设计带来巨大挑战,常规的计算分析方法已不再适用。通过采用平面框架模型和空间三维有限元模型的不同建模方法,解决了不同的结构难题,为该复杂结构的设计实现提供了思路。还通过利用多种结构软件对周边裙房及其基础进行的受力分析,得出一些有益的分析结论和设计体会,为今后类似工程提供参考借鉴。     

建造故事 山姆·瑞吉威对马可·弗拉斯卡里的访谈

文章记录了作者与意大利建筑师、建筑理论学家马可.弗拉斯卡里的访谈。在这场以"建造"为主题的长篇访谈中论述了包括材料、物质性、技艺在内的多个主题,并且以帕拉第奥、斯卡帕等人的多个作品为例,深入浅出地阐释不同历史语境下由建造产生的建筑表达与意义上的丰富性。这与现代建筑、现代建筑教育中视中性的空间与材料为理想观点形成鲜明的反差,也因此构成对"建构"话语独树一帜的讨论与补充。