Assessment of sustainable wastewater handling in sewerless settlements
Summary and conclusions
This report summarises the result of the project "Assessment of sustainable wastewater handling in sewerless settlements", which was conducted during October 1998 – December 2001 under a Danish research programme on ecological urban renewal and wastewater treatment.
The project has resulted in a coherent concept for planning and assessing solutions to sustainable handling of wastewater in areas without conventional sewer systems (sewerless settlements), such as farm houses, summer cottages, garden allotments, villages and ecological settlements planned with a view to avoiding sewers. The concept, or decision support system, contains the following main elements:
 | The on-site analysis, which ensures that the planning process accounts for local conditions that can be significant for the sustainability of a solution. |
| The dialogue workshop, which may be used to create dialogue between different stakeholders and clarify their preferences. |
| The technology information tool, which can provide an overview of the technological possibilities. |
| The assessments, which can be used to compare different technical solutions on a holistic basis. |
A number of tools, case study reports and other publications that expose the main elements mentioned above are made available through the Internet (www.er.dtu.dk/projects/kloaklose). Using the web-media sets a new stage for communicating information to a broad target group, especially when there is a large need for updating information. The content of the main web site is summarised in this report, which has the following content:
Chapter 2 gives an account of a number of definitions of the concept sustainable development and explains how methodologies for sustainability assessment appear very different, depending on whether a quantitative or a qualitative approach is followed and whether focus is on the environment or on people.
Chapter 3 describes the project working method, which is based on parallel planning and assessment of wastewater systems with emphasis on the four elements mentioned above. In addition, eight basic assessment criteria are put forward, based on a demand for coherent assessment of sustainability; 1) environmental stress and resource consumption, 2) hygiene and safety, 3) operation and maintenance, 4) use and cleaning, 5) economy, 6) self-government, 7) durability, and 8) demonstration value.
Chapter 4 summarises the main features of the empirical work, concentrated in five selected cases:
| Wastewater planing in an eco-village, Munkesøgaard, Roskilde |
| Urban ecology in planning of the Hvissinge Vest district, Glostrup |
| Local handling of wastewater in garden allotments |
| Options for sustainable handling of wastewater at Christiansø – a small island in the Baltic |
| Assessment of wastewater handling in the country - a case study of Hillerød municipality |
Chapter 5 gives a and overview of the content and structure of the above mentioned web site. Chapter 6 briefly summarises the case work, discusses the results in view of other activities under the same research programme and highlights the barriers for local wastewater solutions that have been identified in the project. Finally the use of assessment methods and the perspectives for further work in continuation of this project are discussed. Chapter 7 sums up the main conclusions of the project:
| A method for systematic and coherent planning and assessment of solutions for sustainable handling of wastewater in sewerless settlements has been developed. Eight basic criteria are evaluated and subsequently weighted in proportion to each other for specific wastewater solutions, thereby making the final assessment more transparent. |
| Not all eight criteria are easily evaluated. It was e.g. not possible to evaluate hygienic conditions and safety so that that they could be compared and assessed against other criteria such as economy. The environmental stress criteria is furthermore mostly a matter of controlling that the discharges are sufficiently reduced to comply with the established regulations. There is a need for developing better methods for evaluating sustainability criteria and facilitating comparison and assessment. |
| Different stakeholders have very different views towards criteria for sustainable wastewater handling. Thus, there is a need for involving the users in the planning process and in the choice between different solutions to wastewater handling. The dialogue workshop has been developed as a tool for involving interest grups and individuals in decisions related to alternative wastewater handling. |
| The optimal solution to wastewater handling varies depending on the context and the location. A guiding tool has therefore been developed to assist planners in conducting on-site analysis in practice. This tool may also be useful in other planning situations not directly related to wastewater handling. |
| It is of primary importance to have a good overview of alternative technologies for wastewater handling. An electronic information tool (an Internet catalogue) has therefore been developed, containing mass balances for selected components, processes and systems for wastewater handling - but also communicating other types of information relevant in planning and assessment. Clearly, there is a potential and a need for further development of many of the studied technologies. The information tool is structured to facilitate easy updating in step with the expected increase of knowledge. |