Simulating organic pollutant flows in urban stormwater: development and evaluation of a model for nonylphenols and phthalates.

Stormwater-quality models can be useful tools for predicting pollutant loads and identifying sources of contamination. Most models in current use handle pollutants such as metals, nutrients and suspended solids, whereas models including emerging organic contaminants are rare. This study aims at developing and evaluating a model for simulating stormwater flows of two groups of organic pollutants; nonylphenols and phthalates. Sources, emission patterns and environmental fate were examined to create a model framework for the organic contaminants. The model was calibrated using field data from three urban catchments. The results show that the simulated pollutant concentrations are overestimated compared to the measured concentrations, which are often close to or below the analytical detection limit. The high uncertainty and the low predictive power of the model may be explained by factors such as incorrect catchment data, lack of knowledge on buildup, washoff and other processes involved in substance fate, and an underreporting of pollutant concentrations in stormwater. More data on release patterns and sewer fate are needed to adequately simulate stormwater concentrations of nonylphenols and phthalates. A conventional substance flow analysis based on bookkeeping, evaluated in parallel to the computer model, has proven to be useful for calculating fluxes of nonylphenols and phthalates in urban catchments.

A framework for planning of sustainable water and sanitation systems in peri-urban areas.

There are billions of people around the world that lack access to safe water supply and basic sanitation, a situation which puts the affected in severe health conditions as well as economical and social despair. Many of those lacking adequate water supply and sanitation systems can be found at the fringe of the cities in so called peri-urban areas, especially in the developing world. Planning in these areas is highly complex due to challenging environmental and physical conditions, high population density and unclear institutional boundaries. This article presents a framework aiming to support the planning process for sustainable water and sanitation systems in peri-urban areas. The suggested framework is based on different available planning approaches from a review of literature and websites of organisations and companies. It consists of a recommendation of important steps in the planning process as well as supporting tools. Further, it incorporates a set of sustainability criteria important for the peri-urban context and allows for the development of site specific systems. The framework has the aim to be flexible for different planning situations, and for suiting planners with different perspectives and amount of resources.

Ab initio characterization of C5.

In this paper, the structure and spectroscopic parameters of the C5 cluster are determined using multiconfigurational quantum chemical methods as implemented in the MOLCAS software. A number of spectroscopic properties (band center positions, l-doubling parameters, and rotational constants) have been characterized. From the new results, the assignments of previous astrophysical observations [J. Goicoechea et al., Astrophys. J. 609, 225 (2004)] are discussed. A detailed exploration of the global potential energy surface confirms that C5 has a X1Sigmag+ linear isomer of prominent stability and, at least, three minimum energy structures showing singlet electronic ground states. Two of them are cyclic and one has a nonplanar geometry. Vertical and adiabatic electronic transitions and vibrational spectroscopic parameters are determined for the most stable linear isomer using multiconfigurational second order perturbation theory (CASPT2) using an active space containing 12 valence orbitals with 12 active electrons and extended ANO-type basis sets. The infrared spectrum has been analyzed from an anharmonic force field derived form the local surface, determined from the energies of a grid of 1350 geometries. The force field includes four coupling terms. The CASPT2 band center position of the nu7(piu) anharmonic fundamental has been calculated to be at 102 cm(-1), which validates the assignment to C5 of the pattern of bands centered at 102 cm(-1) observed with the ISO telescope.

Polycyclic aromatic hydrocarbons and metals in snow along a highway.

Snow quality and its variations due to distance from the road were studied. Also, how the snow quality changes over time during the melting period was discussed. Snow samples were collected at three occasions during the winter of 2004. The samples were taken along a highway in the Luleå region, Sweden, with an average daily traffic load of 9200 vehicles. Snow samples were taken perpendicular to the road and at different distances. The snow samples were analysed for metals and polycyclic aromatic hydrocarbons (PAH). Also, weather parameters such as temperature, precipitation, and wind speed and wind direction were measured. The highest total metal and PAH concentrations were found at the sample site closest to the road and at the end of the season. Before the melting period started, 42-57% of the total amount of metals and PAH were found in the first 1 m of the snow pack. This information could be valuable when one is discussing how to achieve sustainable snow-handling management.

Evaluation of the ReVAQ project to achieve safe use of wastewater sludge in agriculture.

The use of wastewater sludge on arable land in Sweden has been limited for some years due to the low quality, in some respects, of the sludge and to the reluctance of farmers and the food industry to use it. To improve the quality of the sludge, the ReVAQ project has been started, and it now involves seven municipal wastewater organisations. The goal of the project is to introduce a process in which the quality is successively improved by a series of actions taken by society. These actions include tracking and eliminating sources of heavy metals and other substances. As there are numerous sources of some of the substances, the work concentrates on the major sources. Another important activity is to provide information to the users of the wastewater system. The project is being evaluated by Urban Water AB. The results from the first two years indicate that it may be possible to reach the primary technical goal: to obtain a sludge quality that corresponds to that of household wastewater. The more ambitious goal of reaching a quality corresponding to that of WC water (the sum of urine and faeces) does not seem realistic without far-reaching changes in society. The organisations involved, which take the work seriously and are goal-oriented, have achieved measurable results in a short time. The work is also accepted and supported by the board members. More effort is needed, however, to inform the users about the system, and to [motivate them to] change their behaviour regarding matters such as the purchase of everyday products and the use of the toilet facilities.

Decision support tools for urban water and wastewater systems--focussing on hazardous flows assessment.

The Swedish research programme Urban Water has developed a concept of a multi-criteria basis intended to support decision-making for urban water and wastewater systems. Five criteria groups were established for sustainability assessment of urban water systems: Health and Hygiene, Environment, Economy, Socio-culture, and Technology. Each criterion requires a set of indicators corresponding to quantifiable facts and figures, or qualitative data to comparatively assess the different alternatives in the decision process. The decision support process starts as a baseline study where the existing conditions are addressed. Alternative strategies of the future urban water system are developed and analysed by different tools and methodologies in assessing the five criteria groups. Eventually, the results and conclusions are integrated and synthesised into a basis for decision-making. As an example of a decision support basis for chemical safety, a barrier perspective was introduced to find out if and to what extent hazardous substances can be stopped, diverged, or transformed at various points in the wastewater system. A set of barriers was suggested, i.e. behaviour, systems design, process design, optional recipients, and organisational. The barrier approach was applied to two alternative municipal wastewater system designs--a combined wastewater system vs. a source separated system--analysing the fate of phosphorus, cadmium, and triclosan. The study showed that the combined system caused a higher substance flow to the receiving waterbody than the separated system. The combined system also brought more phosphorus and cadmium to the farmland than the separated system, but only half the amount of triclosan.

Spin-orbit ab initio study of alkyl halide dissociation via electronic curve crossing.

An ab initio study of the role of electronic curve crossing in the photodissociation dynamics of the alkyl halides is presented. Recent experimental studies show that curve crossing plays a deterministic role in deciding the channel of dissociation. Coupled repulsive potential energy curves of the low-lying n-sigma(*) states are studied including spin-orbit and relativistic effects. Basis set including effect of core correlation is used. Ab initio vertical excitation spectra of CH(3)I and CF(3)I are in agreement with the experimental observation. The curve crossing region is around 2.371 A for CH(3)I and CF(3)I. The potential curves of the repulsive excited states have larger slope for CF(3)I, suggesting a higher velocity and decreased intersystem crossing probability on fluorination. We also report the potential curves and the region of curve crossing for CH(3)Br and CH(3)Cl.

Comparison of the effects of using local and central snow deposits: a case study in Luleå.

The aim of the study was to determine if an increased use of local land-based snow deposits would be more sustainable than the use of a central snow deposit. The study focused on transport related emissions, costs for transporting the snow, technical attendance, local effects, public acceptance, land use, effects on the recipient environmental control and potential for accidents. General information was obtained from an inventory regarding snow handling that was made in 14, geographically spread, Swedish municipalities during 2001. The comparison of costs for transporting snow and transport-related emissions was based on information gathered from the municipality of Luleå. The study showed that using local land-based snow deposits would decrease traffic-related emissions such as CO2, CO and NO(x) by 40% annually and would decrease the annual cost for transporting snow by nearly 80%. On the other hand local snow deposits may lead to an increased risk of accidents and to negative local effects such as delayed growing season, flooding and drainage problems. Available land for local snow deposits in the cities is hard to find, and is usually expensive. Therefore a combination of local and central snow deposits is likely to be the most realistic option.

Stormwater management in a catchbasin perspective--best practices or sustainable strategies?

A strategy for sustainable stormwater management is needed. This study has focused on the relative importance of stormwater as a pollutant source in a catchbasin, if Best Management Practices (BMPs) result in pollutant removal or pollutant redistribution, and methods for screening of stormwater strategies. Stormwater is most likely an important pathway for pollutants in a catchbasin perspective. True pollutant removal can only be achieved if the pollutant sources are eliminated. Until that is reached, we should have the best possible control of the pollutant fluxes in the watershed. This study indicates that the search for a sustainable stormwater strategy could be easier to handle if different "screens" could be used. The Swedish environmental objectives, which try to encapsulate all aspects of sustainability, may be used as a foundation for a "sustainability screen". By using this screen, the "unsustainable" features of different stormwater strategies could be pointed out. A "standards and legislation screen" will be based on the EU Water Framework Directive. As this study has shown, it is doubtful whether the conventional BMPs, such as stormwater ponds and infiltration facilities, produce a sufficient pollutant control.

Workshop 8 (synthesis): challenges of expanding ecological sanitation into urban areas.

After seven papers discussing specific examples of ecological sanitation projects, the workshop considered the background, motivation and feasibility of this technology. It was agreed that ecological sanitation could help tackle water scarcity, health protection and, by recycling water and nutrients into agriculture, food scarcity. Dense cities are probably unsuitable for its implementation, but rural, town and peri-urban areas are promising. Key issues that remains are: the microbiological and chemical risks associated with the technology; the need for major information, education and support programmes; effective linking to reuse schemes; tailoring systems to meet local physical, socio-economic and cultural circumstances.