Is semi-flocculation effective as pretreatment to ultrafiltration in wastewater treatment?

In this study, ferric chloride (FeCl(3)) flocculation was used as a pretreatment to ultrafiltration (UF) in treating synthetic wastewater containing synthetic organic matter (SOM). The effect of flocculant dose was studied in terms of organic removal and membrane flux decline. The UF with optimum dose of FeCl(3) (68 mg L(-1)) did not experience any flux decline during the whole operation of 6 h. The preflocculation with a smaller dose of 20 mg L(-1) of FeCl(3) led to a severe flux decline in the UF (more than 65% in 6 h). To understand the phenomenon of the flux decline of UF, the MW ranges of SOM removed by different doses of FeCl(3) and by the post treatment of UF were studied. Flocculation with at least 50 mg L(-1) of FeCl(3) dose was found to be necessary to avoid any significant flux decline and to obtain superior DOC removal.     

Is the association between temperature and mortality modified by age, gender and socio-economic status?

Background

A number of studies have examined the relationship between high ambient temperature and mortality. Recently, concern has arisen about whether this relationship is modified by socio-demographic factors. However, data for this type of study is relatively scarce in subtropical/tropical regions where people are well accustomed to warm temperatures.

Objective

To investigate whether the relationship between daily mean temperature and daily all-cause mortality is modified by age, gender and socio-economic status (SES) in Brisbane, Australia.

Methods

We obtained daily mean temperature and all-cause mortality data for Brisbane, Australia during 1996-2004. A generalised additive model was fitted to assess the percentage increase in all deaths with every one degree increment above the threshold temperature. Different age, gender and SES groups were included in the model as categorical variables and their modification effects were estimated separately.

Results

A total of 53,316 non-external deaths were included during the study period. There was a clear increasing trend in the harmful effect of high temperature on mortality with age. The effect estimate among women was more than 20 times that among men. We did not find an SES effect on the percent increase associated with temperature.

Conclusions

The effects of high temperature on all deaths were modified by age and gender but not by SES in Brisbane, Australia.     

Is it possible to estimate atmospheric deposition of heavy metals by analysis of terrestrial mosses?

Here we present a critical review of diverse research studies involving estimation of atmospheric deposition of heavy metals from the concentrations of the contaminants in terrestrial moss. The findings can be summarized as follows: i) significant correlations between the concentrations of contaminants in moss and bulk deposition were observed in only 40.1% of the cases in which the relationship was studied and in only 14.1% of the cases, the coefficient of correlation was > 0.7; ii) some method-related problems were identified (i.e. small sample sizes, elimination of some data from the regression analyses, large distances between the moss sampling sites and the bulk precipitation collectors, differences in times of exposure of the moss samples and collection times for the bulk precipitation), so that the results of the studies may not be completely valid, and iii) evidence was found in the relevant literature that moss does not actually integrate the atmospheric deposition received. We also discuss the reason why, in accordance with the published data, bulk deposition cannot be correctly estimated by determination of the final concentrations of contaminants in the organism, such as the existence of different sources of contamination, the physicochemical characteristics of the sources of deposition, physicochemical processes to which the organism is subjected and the biological processes that take place in the moss. Taking into account the above findings, it was concluded that, except for certain elements and specific cases (i.e. Pb and Cd), atmospheric deposition of elements cannot be accurately estimated from the concentrations of metals and metalloids in moss tissues. However, the analysis of moss does provide information about the presence of contaminants in the atmosphere, their spatial and temporal patterns of distribution and how they are taken up by live organisms. Use of mosses is therefore recommended as a complementary (rather than an alternative) technique in the conventional analysis of bulk deposition of contaminants.     

Is ecosystem structure the target of concern in ecological effect assessments?

The species sensitivity distribution, a technique currently used to derive water-quality standards of chemicals, is associated with a set of inadequately tested assumptions. One of these assumptions is that ecosystem structure is as or more sensitive than ecosystem function, i.e., that structure is the target of concern. In this paper, we tested this assumption for a simple freshwater ecosystem exposed to different toxicants. Using an ecosystem model, we calculated no observed effect concentrations (NOECs) for ecosystem structure (ecosystem structure-NOECs) and function (ecosystem function-NOECs) for each of 1000 hypothetical toxicants. For 979 of these toxicants, the ecosystem structure-NOEC was lower than or equal to the ecosystem function-NOEC, indicating that the tested assumption can be considered valid. For 239 of these 979 toxicants, both NOECs were equal. For half of the 1000 toxicants, the structure of lower trophic levels (i.e., phytoplankton) appears to be more sensitive than the structure of higher trophic levels (i.e., fish). As such, ecosystem structure-NOECs are primarily determined by the sensitivity of the structure of lower trophic levels. In contrast, ecosystem functions associated with higher trophic levels (e.g., total ingestion by fish) are more sensitive than functions associated with lower trophic levels (e.g., total photosynthesis by phytoplankton) for 749 toxicants.     

Is the human right to water sufficiently protected in Spain? Affordability and governance concerns

Most research on water poverty focuses on developing countries. However, research is also needed in developed countries, where water may be too expensive for some households. This paper examines the case of Spain, using data from 16 cities that combined are home to 35% of the Spanish population. We study both national and local systems of regulation and governance. The objective is to determine whether low-income families face a genuine threat of exclusion from water supply. To this end, we analysed whether the Spanish legal framework allows that water supply is cut off for non-payment of the bill. We also did different estimates of the percentage of the family income spent on the water bill, which in some cases can surpass 10%. The estimates account for tariff discounts, as well as assistance programmes available to those who are struggling to pay their water bill. Although there is no problem of affordability for an average Spanish family in general, we conclude that families at risk of poverty face a real threat of exclusion from water services because they are not able to pay for them and the institutional framework does not sufficiently protect them.     

Is the digestive gland of Mytilus galloprovincialis a tissue of choice for estimating cadmium exposure by means of metallothioneins?

A study performed over 12 months with caged mussels Mytilus galloprovincialis in the coastal marine zone, which is under urban pressure, reveals a temporal variation of digestive gland mass, which causes "biological dilution" of cytosolic metallothionein (MT) and trace metal (Cd, Cu, Zn, Fe, Mn) concentrations. The dilution effect was corrected by expressing the cytosolic MT and metal concentrations as the tissue content. Consequently, the changes of the average digestive gland mass coincide with the changes of MT and trace metal contents. From February to June, MT contents are nearly twice and trace metal contents nearly three times higher than those of the other months. The period of increased average digestive gland mass, of MT and trace metal contents probably overlaps with the sexual maturation of mussels (gametogenesis) and enhanced food availability. Since natural factors contribute more to the MT content than the sublethal levels of Cd, the digestive gland of M. galloprovincialis is not considered as a tissue of choice for estimating Cd exposure by means of MTs.     

Going too far in the battle against concentration? On the balance between supply and demand of social housing in Dutch cities

In the second half of the 1990s, Dutch urban housing policy shifted from urban renewal to urban restructuring and the creation of more socially mixed neighbourhoods. Motives for restructuring stem from the ongoing debates on concentration, segregation and social mix. Here, we focus on the main instruments of urban restructuring, that is, the demolition of social housing and the construction of more expensive rental and owner-occupied housing. Continued restructuring may eventually lead to a shortage of social rented dwellings for low-income households, the target group of social housing. An important political question is therefore whether the dwindling supply of social housing still matches the potential demand in the target group. We addressed this question with an analysis of three Dutch cities: Rotterdam, The Hague and Breda. The results indicate that, although demolition has brought about substantial changes, the share of social rented housing remains high in most restructuring neighbourhoods and restructuring has not resulted in concentrations of social rented housing in other, non-restructuring neighbourhoods in any of the three cities. In Rotterdam, which had a very large social housing stock at the beginning of the restructuring operation, there are still sufficient affordable homes for lower income households. However, in The Hague and Breda, restructuring has tightened the supply of social rental housing. The municipal authority in The Hague has attempted to remedy the situation by entering regional agreements to secure sufficient levels of affordable housing.     

From pragmatic to politicized? The future of water remunicipalization in the United States

The United States has experienced swings of public and private operation of its water services for more than 150 years. This paper examines the most recent swing, that of remunicipalization. We argue that much of this remunicipalization is taking place for ‘pragmatic’ reasons related to cost savings and service quality, but there are also signs of more ‘politicized’ forms of water remunicipalization taking place, similar to efforts elsewhere in the world where the process has often involved heated ideological debates and mass mobilizations. Combined with a growing politicization of other social, economic, and environmental issues in the US, water remunicipalization could become more politicized in the future, but a fragmented ‘pro-public’ movement, combined with ongoing efforts to outsource water services and growing resistance to remunicipalization from private water companies, may constrain this potential.     

Have the bioavailabilities of trace metals to a suite of biomonitors changed over three decades in SW England estuaries historically affected by mining?

Many estuaries of southwest England were heavily contaminated with toxic metals associated with the mining of copper and other metals, particularly between 1850 and 1900. The question remains whether the passage of time has brought remediation to these estuaries. In 2003 and 2006 we revisited sites in 5 metal-contaminated estuaries sampled in the 1970s and 1980s — Restronguet Creek, Gannel, West Looe, East Looe and Tavy. We evaluate changes in metal contamination in sediments and in metal bioavailabilities in sediments and water to local organisms employed as biomonitors. We find that the decline in contamination in these estuaries is complex. Differences in bioavailable contamination in the water column were detectable, as were significant detectable changes in at least some estuaries in bioavailable metal contamination originating from sediments. However, in the 100 years since mining activities declined, bioavailable contamination has not declined to the regional baseline in any estuary affected by the mine wastes. The greatest decline in contamination occurred in the one instance (East Looe) where a previous industrial source of (Ag) contamination was considered. We used the macroalgae Fucus vesiculosus and Ascophyllum nodosum as biomonitors of dissolved metal bioavailabilities and the deposit feeders Nereis diversicolor and Scrobicularia plana as biomonitors of bioavailable metal in sediments. We found no systematic decrease in the atypically high Ag, Cu, Pb and Zn concentrations in the estuarine sediments over a 26 year period. Accumulated metal (Ag, As, Cu, Pb, and Zn) concentrations in the deposit feeders are similarly still atypically high in at least one estuary for each metal, and there is no consistent evidence for general decreases in sediment metal bioavailabilities over time. We conclude that the legacy of mining in sheltered estuaries of southwest England is the ongoing presence of sediments rich in metals bioavailable to deposit feeders, while dissolved metal bioavailabilities from this historical source alone are no longer atypically high.     

Do uncertainty analyses reveal uncertainties? Using the introduction of DNA vaccines to aquaculture as a case

The Walker and Harremo?s (W&H) uncertainty framework is a tool to systematically identify scientific uncertainty. We applied the W&H uncertainty framework to elicit scientists' judgements of potential sources of uncertainty associated with the use of DNA vaccination in aquaculture. DNA vaccination is considered a promising solution to combat pathological fish diseases. There is, however, lack of knowledge regarding its ecological and social implications. Our findings indicate that scientists are open and aware of a number of uncertainties associated with DNA vaccination e.g. with regard to immune response, degradation and distribution of the DNA plasmid after injection and environmental release, and consider most of these uncertainties to be adequately reduced through more research. We proceed to discuss our experience of using the W&H uncertainty framework. Some challenges related to the application of the framework were recognised. This was especially related to the respondents' unfamiliarity with the concepts used and their lack of experience in discussing qualitative aspects of uncertainties. As we see it, the W&H framework should be considered as a useful tool to stimulate reflection on uncertainty and an important first step in a more extensive process of including and properly dealing with uncertainties in science and policymaking.     

Is planning delay really a constraint in the provision of housing? Some evidence from Israel

This paper revisits the claim that a causal link exists between the inflexibility of land-use planning and low elasticity of housing supply. A theoretical model of factors impacting district-level planning is presented alongside a model of the impact of planning delay on housing supply. The models are estimated for the Tel Aviv district using detailed data covering a 12-year period. Results show significant impacts on planning delay due to plan, municipality and district planning commission characteristics. House prices exert a positive effect on planning speed and municipal funding acts as a supply constraint. While planning delay does not impact housing supply, delay uncertainty has a negative impact and acts as a constraint.     

Is phenol condensation one of the major pathways in the formation of polychlorinated dibenzofurans in municipal waste incinerators?: Model prediction vs. field observation

The role of phenol condensation pathways in the formation of polychlorinated dibenzofurans (PCDF) in a municipal waste incinerator was assessed by comparing predicted PCDF homologue and isomer patterns with those obtained from the incinerator. A two-phenol condensation model, dependent only on the distribution of phenols, was used to predict the distributions of PCDF congeners in the incinerator. Complete distributions of phenols and PCDF congeners were obtained from the incinerator. To quantify the degree of agreement between obtained isomer distributions and those predicted by the model, R-squared values from linear correlations were calculated for the dichlorinated- through hexachlorinated-isomers. They ranged from 0.001 to 0.1. Agreement between obtained and predicted PCDF isomers was very poor for all homologues, suggesting that phenol condensation pathways are unlikely to be the primary route in the formation of PCDF in the incinerator. However, dibenzofuran (DF) is likely to be produced from a condensation of two phenols. This paper shows the use of PCDF homologue and isomer patterns calculated by the two-phenol condensation model for testing PCDF formation mechanism attribution in a municipal waste incinerator.     

Housing Associations in the Republic of Ireland: Can They Respond to the Government's Challenge for Major Expansion?

In the late 1990s, faced with rapid escalation in house prices and rising housing stress, politicians and policy-makers in the Republic of Ireland expressed widespread concern about inadequacies in social housing provision. In one of a series of responses the government has recently announced an ambitious plan to promote and to resource the existing small housing association movement so that its annual output would increase eightfold in the early years of the new century. There is little existing research on the work of housing associations in the Republic of Ireland or about their contribution to housing provision and policy and there is clearly an urgent need for a careful analysis of the capacity of the voluntary sector and of its strengths, weaknesses and potential. Pending such a study, this paper aims to provide an overview of the voluntary sector's development in the context of the evolution of Irish housing policy and considers some of the developmental and policy issues which will arise from the government's decision to promote the voluntary and co-operative sector.     

How does the community resilience of urban village response to the government-led redevelopment? A case study of Tangjialing village in Beijing

Building on the critical resilience literature, this study aims at analyzing how the community resilience (CR) of urban village (UV), which is challenged by multiple natural and socio-economic disturbances such as climate change, land occupation, and industrialization, responses to the government-led redevelopment (GLR) and its hidden mechanism. A conceptual framework incorporating social, economic, institutional/governmental, material domains and community capital was established with reference to the work of Cutter, Burton, and Emrich (2010), and was applied as the conceptual springboard to assess the resilience of Tangjialing village. The results suggested that the GLR in Tangjialing village was generally a successful practice for enhancing CR, which was tightly associated with the economic empowerment for local residents and formalization of informal economic activities and negatively affected by insufficient public engagement. Accordingly, policy implications about enhancing the resilience such as protecting the farmers' “private rights” as landowners, providing employment guidance and assistance and implementing cooperative planning were proposed.     

Is there an endogeneity problem between health and apartment value? Gender differences and the impact of obesity on property self-evaluation

Journal of Housing and the Built Environment - Background Numerous studies have compared self evaluation and market values of apartments by employing hedonic regressions. Most of these studies...