Mercury pollution is a cause of high concern for European freshwaters. In this study, we use modelled atmospheric deposition and novel high-resolution water cover and impervious urban areas data to ...quantify the input of Mercury to European rivers and lakes. This information, combined with estimates of releases from industrial installations and urban wastewater and from soils, yields an overall European budget of water Mercury. Compared to previous estimates, the calculation highlights that direct deposition to permanent and temporary inland water surfaces is a dominant source of pollution. We also show that an important source is the washout of impervious urban surfaces, while releases from soil and industrial and urban wastewater play a lesser, albeit sizable role. The contribution of wastewater to Mercury releases is expected to decrease over time because of more stringent regulations on Mercury use. The analysis confirms that reducing atmospheric deposition (hence air releases) of Mercury remains the single key action to control pollution. However, we show that control of urban runoff discharges to water bodies may be the most effective water management measure in order to reduce Mercury input to coastal and in-land water bodies.
A waste stabilisation pond system comprising two ponds was used to treat a seasonal discharge from a summer campsite in the UK. Despite a short retention time and relatively high surface loading, the ...first pond was able to acclimate rapidly to the incoming wastewater, although dissolved oxygen (DO) concentrations remained low. Successful operation was due in part to initial dilution of incoming load at the start of the season by treated water retained over the winter period. The two ponds in series produced a final effluent which met typical chemical and biochemical oxygen demand standards for discharge to inland waters; as expected nutrient concentrations were above typical limit values, making land application for irrigation a preferred option. The system performance was adversely affected by short periods (3–4 days) of low average light intensity, leading to reduced chlorophyll-a and DO concentrations which did not immediately respond to subsequent increases in irradiance. A light-dark bottle technique, adapted to determine net oxygen production potentials under standard conditions of illumination, mixing and temperature, was found to provide an excellent indicator of pond metabolic status and treatment potential.
•First use of the light-dark technique to indicate WSP metabolic status.•Higher than expected loading could be achieved on the first pond.•Short periods of low light intensity can affect system performance.•Start-up without acclimatisation achieved by retaining treated effluent over winter.•Pond effluent could meet BOD and COD discharge standards to inland water.
Micropollutants (MPs) in wastewater pose a growing concern for their potential adverse effects on the receiving aquatic environment, and some countries have started requiring that wastewater ...treatment plants remove them to a certain extent. Broad spectrum advanced treatment processes, such as ozonation, activated carbon or their combination, are expected to yield a significant reduction in the toxicity of effluents. Here we quantify the reduction of effluent toxicity potentially achieved by implementing these advanced treatment solutions in a selection of European wastewater treatment plants. To this end, we refer to a list of “total pollution proxy substances” (TPPS) composed of 1337 chemicals commonly found in wastewater effluents according to a compilation of datasets of measured concentrations. We consider these substances as an approximation of the “chemical universe” impinging on the European wastewater system. We evaluate the fate of the TPPS in conventional and advanced treatment plants using a compilation of experimental physicochemical properties that describe their sorption, volatilization and biodegradation during activated sludge treatment, as well as known removal efficiency in ozonation and activated carbon treatment, while filling the gaps through in silico prediction models.
We estimate that the discharge of micropollutants with wastewater effluents in the European Union has a cumulative MP toxicity to the environment equal to the discharge of untreated wastewater of ca. 160 million population equivalents (PE), i.e. about 30 % of the generated wastewater in the EU. If all plants above a capacity of 100,000 PE were equipped with advanced treatment, we show that this load would be reduced to about 95 million PE. In addition, implementing advanced treatment in wastewater plants above 10,000 PE discharging to water bodies with an average dilution ratio smaller than 10 would yield a widespread improvement in terms of exposure of freshwater ecosystems to micropollutants, almost halving the part of the stream network exposed to the highest toxic risks.
Our analysis provides background for a cost-effectiveness appraisal of advanced treatment “at the end of the pipe”, which could lead to optimized interventions. This should not be regarded as a stand-alone solution, but as a complement to policies for the control of emissions at the source for the most problematic MPs.
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•We build indicators of cumulative micropollutant toxicity of wastewater in the EU.•Toxicity evaluated from 1337 proxy substances and estimated treatment removal.•Current toxicity equivalent to untreated sewage discharge of 160 million people.•Advanced treatment at large wastewater treatment plants reduces this to 95 million.•Advanced treatment also at smaller plants approximately halves current pollution.
This practical A4 pack contains activities and ideas for teachers and students to learn more about learning. Learning about Learning is a practical way of teaching important and neglected theories of ...learning. The idea is that if teachers and students learn about what learning is and how it happens they understand a greater range of learning possibilities and approaches and improve their learning and teaching skills.
In previous surveys of North Sea sediments, arsenic has often been omitted from the range of metals analysed. In this study we analysed archived samples from these earlier surveys and combined the ...data with recent results for the Dogger Bank, to examine the distribution of total arsenic in sediments from the western North Sea and Humber Estuary. Historically, the Humber has been subjected to a large point discharge of arsenic from an industrial source, and so there is interest in investigating the extent of contamination in the area. Normalization of arsenic concentrations to those of the clay analogues aluminium or rubidium did not prove to be statistically appropriate for the whole of the surveyed area. However, normalization to iron (representing iron (oxy-)hydroxide coatings with which arsenate has a high affinity) did show strong relationships for sediments from the whole of the region studied. This procedure showed elevated arsenic concentrations to be present in sediments from the outer Thames and off north east Norfolk, while those from the Humber were close to their predicted value. The Humber receives a large amount of iron from industrial discharges, providing a possible source of material for iron (oxy-)hydroxides. Although arsenical waste disposal could explain the high arsenic concentrations in sediments from the outer Thames, the causes for those off north east Norfolk are as yet unclear.
Historically, solid waste from chromite ore processing has been disposed of at a number of sites in Glasgow, Scotland. Leachate from these sites has been implicated as a source of chromium (Cr) ...contamination to both groundwaters and stream waters in the south east area of the city. In this study, chromium speciation has been determined in ground-, stream-, river- and pore waters, to assess the extent of contamination and the associated risk. The speciation of chromium is important, as the trivalent species of chromium (Cr(III)) is an essential form of the element, while hexavalent chromium (Cr(VI)) is a known carcinogen to humans via inhalation. Concentrations of total chromium have also been determined in sediments from the River Clyde, to assess the significance of local concentrations relative to those elsewhere in the catchment. High concentrations of Cr(VI) were found in groundwaters and streamwaters in the area immediately surrounding the contaminated sites, and high concentrations of chromium were also found in River Clyde sediments downstream of these sites. However, these concentrations rapidly decrease away from the chromium-contaminated south eastern side of the city. Data from porewaters suggest that some reduction of Cr(VI) occurs naturally in the sediments, indicating that the risk posed by high concentrations of Cr(VI) should be decreased over the longer term.
This thesis builds on the first configuration model developed and expanded in the IFS. The model considers the factors that impact on managers as they undertake performance management of their staff. ...This thesis transforms the original model through a second and into a third and final configuration. The questions that underpin this research are concerned with managers' experiences as they engage in managing performance and explore the triggers that enable managers to begin a process of, and sustain, managing underperformance within their team. The methodology and research approach adopted is that of social construction which allows managers' worlds to be co-constructed. In undertaking this study, researcher reflexivity was developed, by engaging with colleagues and other interested individuals. The research discourse was not a neutral process and emotioning in research was explicitly recognised. The research design and methods of data collection worked with senior managers across public and private sectors and also engaged with manager groups to provide situations where emerging constructions could be worked up. This continuing professional engagement gave a way of interacting with the emerging discourse to refine the constructions. The research findings identify the significance of contextual factors within any manager's world and the increasing importance of external conditions such as Best Value. The idea of potent and impotent organisations in sustaining a high performance culture is created and the characteristics of each identified. The concept of "other" emerged as managers described the individual who was underperforming and the level of fear and emotional impact on them as they engaged with the "other" in performance management. During the research managers described their feelings in different ways but there was a universal factor - managers do have feelings. Performance management is a Wicked Problem and the rhetoric belies the level of complexity that this research has identified namely - There is no definitive Problem, there is no definitive Solution. Finally the research recommends action for policy makers and managers in order to better develop the systems and processes needed to achieve super performance.
