Suchergebnisse

AbstractThe United Nations Drinking Water Supply and Sanitation Decade ran from 1981 to 1990. Much was achieved, but the target of a safe water supply and adequate sanitation for all was not. However, many helpful lessons of experience were derived, and these should guide work in this sector over the next several decades. The paper briefly reviews the achievements of the decade, and considers the lessons learned.

ABSTRACTSound strategies for community water supply and sanitation programmes in developing countries should be based on (i) a clear understanding of the existing problems, (ii) the beneficial impacts achievable, and (iii) the factors which determine sustainability. The impacts of many water and sanitation programmes are limited, and many systems break down and are abandoned prematurely; only limited impacts are achievable in the short term without greatly increased investment. Sustainability, in the sense of continued delivery and uptake of services, is threatened by numerous attitudinal, institutional and economic factors, and community participation approaches alone are no guarantee of success. The key to sustainability is that all stakeholders involved in consumption/use, maintenance, cost recovery, and continuing support, perceive it in their best interests to deliver high‐quality services.This paper, based upon the authors' experiences in Africa and Asia, proposes new sets of programme aims and objectives in relation to impact and sustainability, which can be used in programme design, monitoring and evaluation. It also makes longer‐term recommendations to external support agencies.

ABSTRACT Community water supply programmes in developing countries frequently utilize wells or boreholes equipped with handpumps as the technology of choice. Whilst simple targets concerning numbers of wells to be drilled or villages to be served are often prominent, the wider objectives of such programmes are rarely expressed in quantified terms and, as a consequence, programme impact is often disappointing as well as difficult to evaluate. Because objectives are not clear, programme strategy fails to include all the issues and activities which are necessary to achieve the maximum beneficial impact on participating communities. In the paper, target objectives, checklists of programme activities, and staffing requirements are proposed. The subject of programme impact is briefly discussed, and a realistic approach to programme evaluation is outlined. The paper is intended both as an aid to project planners and as a guide to managers and evaluators of existing well‐handpump programmes.

AbstractAll crops that are eaten raw can present a microbiological risk to consumers. Disease outbreaks in the United Kingdom and United States have illustrated that ready‐to‐eat crops can be a vehicle for the transmission of gastrointestinal disease. Irrigation water has been implicated as a possible source of microbiological contaminants. Over two‐thirds of irrigation water applied to UK salad crops is abstracted from rivers and streams. Many of these are subject to a continuous input of faecal contamination from sewage treatment works as well as intermittent inputs from livestock and sewer overflows. In this paper, we show how geospatial techniques can help to assess the relationships between treated effluent discharges and abstractions and thus provide a new insight into local‐scale assessments of irrigation water quality. The extent to which the approach can inform risk assessments and decision‐making at the farm scale is demonstrated using a case‐study catchment in eastern England.

Grassland application of dairy slurry, cattle dung and biosolids offers an opportunity to recycle valuable nutrients (N, P and K), which may all introduce pathogens to the soil environment. Herein, a temporal risk assessment of the survival of Escherichia coli (E. coli) up to 40 days in line with the legislated grazing exclusion time points after application was examined across six scenarios: (1) soil and biosolids mixture, (2) biosolids amended soil, (3) dairy slurry application, (4) cattle dung on pasture, (5) comparison of scenario 2, 3 and 4, and (6) maximum legal vs. excess rate of application for scenario 2 and 3. The risk model input parameters were taken or derived from regressions within the literature and an uncertainty analysis (n=1000 trials for each scenario) was conducted. Scenario 1 results showed that E. coli survival was higher in the soil/biosolids mixture for higher biosolids portion, resulting in the highest 20 day value of residual E. coli concentration (i.e. C20, log10CFU g−1dw) of 1.0 in 100% biosolids or inoculated soil and the lowest C20 of 0.098 in 75/25 soil/biosolids ratio, respectively, in comparison to an average initial value of ~6.4 log10CFU g−1dw. The E. coli survival across scenario 2, 3 and 4 showed that the C20 value of biosolids (0.57 log10CFU g−1dw) and dairy slurry (0.74 log10CFU ml−1) was 2.9-3.7 times smaller than that of cattle dung (2.12 log10CFU g−1dw). The C20 values of biosolids and dairy slurry associated with legal and excess application rates ranged from 1.14 to 1.71 log10CFU ha−1, which is a significant reduction from the initial concentration range (12.99 to 14.83 log10CFU ha−1). The E. coli survival in un-amended soil was linear with a very low decay rate resulting in a higher C20 value than that of biosolids or dairy slurry. The risk assessment and uncertainly analysis showed that the residual concentrations in biosolids/dairy slurry applied soil after 20 days would be 45−57% lower than that of the background soil E. coli concentration. This means the current practice of grazing exclusion times is safe to reduce the risk of E. coli transmission into the soil environment.

Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populations. To date, most research focused on occupational exposure, whilst much less is known about the impact of emissions from industrial operations on downwind endotoxin concentrations. A review of the literature was undertaken, identifying studies that reported endotoxin concentrations in both ambient environments and around sources with high endotoxin emissions. Ambient endotoxin concentrations in both rural and urban areas are generally below 10 endotoxin units (EU) m−3; however, around significant sources such as compost facilities, farms, and wastewater treatment plants, endotoxin concentrations regularly exceeded 100 EU m−3. However, this is affected by a range of factors including sampling approach, equipment, and duration. Reported downwind measurements of endotoxin demonstrate that endotoxin concentrations can remain above upwind concentrations. The evaluation of reported data is complicated due to a wide range of different parameters including sampling approaches, temperature, and site activity, demonstrating the need for a standardised methodology and improved guidance. Thorough characterisation of ambient endotoxin levels and modelling of endotoxin from pollution sources is needed to help inform future policy and support a robust health-based risk assessment process