Identification of potential sewer mining locations: a Monte-Carlo based approach.

Rapid urbanization affecting demand patterns, coupled with potential water shortages due to supply side impacts of climatic changes, has led to the emergence of new technologies for water and wastewater reuse. Sewer mining (SM) is a novel decentralized option that could potentially provide non-potable water for urban uses, including for example the irrigation of urban green spaces, providing a mid-scale solution to effective wastewater reuse. SM is based on extracting wastewater from local sewers and treatment at the point of demand and entails in some cases the return of treatment residuals back to the sewer system. Several challenges are currently in the way of such applications in Europe, including public perception, inadequate regulatory frameworks and engineering issues. In this paper we consider some of these engineering challenges, looking at the sewer network as a system where multiple physical, biological and chemical processes take place. We argue that prior to implementing SM, the dynamics of the sewer system should be investigated in order to identify optimum ways of deploying SM without endangering the reliability of the system. Specifically, both wastewater extraction and sludge return could result in altering the biochemical process of the network, thus unintentionally leading to degradation of the sewer infrastructure. We propose a novel Monte-Carlo based method that takes into account both spatial properties and water demand characteristics of a given area of SM deployment while simultaneously accounting for the variability of sewer network dynamics in order to identify potential locations for SM implementation. The outcomes of this study suggest that the method can provide rational results and useful guidelines for upscale SM technologies at a city level.

A decision support framework for sustainable urban water planning and management in new urban areas.

The paper discusses issues of decision support within the context of sustainable development and more specifically sustainable water cycle management to provide a context and a rationale for the decision support approach adopted within an on-going U.K. EPSRC-funded project, WaND. The paper proposes a set-up for a flexible, upgradeable, efficient and modular decision support framework and associated tools. Furthermore, the paper presents early prototypes of three decision support tools developed within the proposed framework including initial results for one of them.

Diffuse sources of heavy metals entering an urban wastewater catchment.

New legislation such as the Water Framework Directive (WFD) will require Member States to better understand the concentrations and loads of contaminants entering surface waters. This will include inputs from wastewater treatment plants (WWTP) as well as from other urban, industrial and agricultural sources. A review of available literature revealed a shortage of data on the levels and sources of heavy metals entering WWTP from urban sources. As a consequence, the concentrations of heavy metals (cadmium, chromium, copper, mercury, nickel, lead and zinc) were determined in the wastewater from an urban catchment located in the UK, as part of a project undertaken for UK Water Industry Research (UKWIR). Both foul and surface water samples were taken. Metal concentrations varied considerably in the foul water samples, both between sources and over the course of the week. Concentrations of most metals were higher in the Monday town centre samples, attributed to leaching from stagnant water remaining in the pipework of office buildings over the weekend. Runoff concentrations were higher in the light industrial estate samples than in the domestic samples for all the metals, and exhibited highest levels in the 'first flush' samples, coincident with the initial flow of runoff containing the highest concentrations of suspended solids.

Sources of priority substances entering an urban wastewater catchment--trace organic chemicals.

The implementation of new legislation such as the Water Framework Directive (WFD) requires Member States to gain a better understanding of priority substances entering surface waters. This will include inputs from wastewater treatment works as well as from other urban, industrial and agricultural sources. There is currently a lack of available data regarding the magnitude and sources of organic priority substances entering treatment works. As a consequence the concentrations of organic priority substances including PAHs, surfactants, polybrominated diphenylethers (PBDEs), diethylhexyl phthalate (DEHP), pesticides and solvents were determined in the wastewater from an urban catchment located in the UK, as part of a project undertaken for UK Water Industry Research (UKWIR). Most organic priority substances were detected in the microg/l range. Significant variations in the concentration of linear alkylbenzene sulphonate (LAS), DEHP, PBDEs and nonylphenol ethoxylates (NPEOs), in particular, were observed for the different sources. The greatest differences were evident between new and older domestic discharges. Solvent levels varied considerably reflecting use and production within the catchment. Chloroform levels were highest in domestic effluent, while trichloroethene and tetrachloroethene were detected only in commercial samples.

Integrating river basin management and the coastal zone: the (blue) Danube and the (black) sea.

In order to effectively manage the wide variety of physical, chemical biological and ecological processes in a sensitive coastal environment such as the Black Sea, current environmental management objectives are no longer sufficient: a new management approach has to address the intimate functional linkage between the river basin and the costal environment. Current water quality legislation requires compliance to emission levels based on the chemical analysis of water samples taken at discharge points, such as treatment plants discharging into rivers. While such measures provide a relative indication of the water quality at the point of discharge, they fail to describe accurately and sufficiently the quality of the water received from the watershed or basin. As water flows through the catchment, rainfall run-off from urban and agricultural areas carries sediments, pesticides, and other chemicals into river systems, which lead to coastal waters. The impact of the Kosovo crisis on the Danube ecosystems provides a poignant example of the effects of such diffused pollution mechanisms and reveals a number of interesting pollution mechanisms. This paper discusses both the effects of diffused pollution on the Black Sea, drawing from state-of-the-art reports on the Danube, and proposes a framework for a decision support system based on distributed hydrological and pollution transport simulation models and GIS. The use of ecological health indicators and fuzzy inference supporting decisions on regional planning within this framework is also advocated. It is also argued that even the recently produced GEF document on Black Sea protection scenarios should benefit significantly if the concept of pollution reduction from both urban, industrial and rural areas should undergo a systematic conceptual update in the view of the recent recommendations of the UNEP IETC (2000) document.