Technology selection for water treatment and pollution control

FAQ sheet on technology selection, prepared by Cinara, Colombia

Introduction

Good basic water and sanitation services, both at urban and rural levels, is a fundamental component of development. However, according to PAHO and UNICEF global reports, in 2000, 92 million people in Latin America did not have an adequate supply of drinking water and 128 million did not have access to basic sanitation. This situation has an impact on the health and quality of life of the population in this region, where in spite of great investments, the Water Decade (1980 – 1990) did not have the expected results. This situation is especially critical in small towns, including county towns, grouped rural areas, and peri-urban settlements in big cities.

In view of the need to respond to this situation, the water and sanitation sector has been analysed and its situation reconsidered within the framework of the economic process and modernisation of the state. In the different countries in the region these processes have implicated the investment of billions of dollarsand the implementation of new strategies, such as decentralisation of the water and sanitation sectors and those related to water resources management and environmental protection. These policies tend to strengthen decision-making at local level, especially in rural areas and small and medium-sized towns, where traditionally water resources management has been carried out at central levels of the state. However, in spite of the goodness of these and other strategies their impact will continue to be limited if key factors that allow the existence of efficient and sustainable organisations and drinking water and sanitation facilities are not strengthened. In this overview special attention has been given to the choice of technical solutions to be implemented. Such a choice should be based on knowledge of initial investment - and operation and maintenance costs of different technological options used for treatment of drinking - and wastewater. The summary of technical selection models is followed by some basic concepts which are important when selecting technologies for water treatment.

Technology selection models

Different authors have highlighted the importance of formulating criteria for the process of technology selection of water supply systems. Some authors have specifically focused their work on water treatment, including the cost of the different technological options as a selection criteria. In some cases particular emphasis has been placed on the protection of water supply sources (Okun, 1991). Others recommend that technology selection is carried out based on the quality of water at the source and on the objectives of the treatment according to existing regulations (Di Bernardo, 1991). Pérez (1989) has presented a model for selecting the source for a water system based on construction costs and the operation and maintenance of water treatment systems.

Various methodologies have been developed in the field of sanitary and environmental engineering—especially indeveloping countries— to support the work of planners in the selection processes of sustainable technology for treatment of water for human consumption and domestic wastewater. The model developed by the University of Oklahoma is an example of such a method (Reid, 1982). Later, other models were developed using the multiple criteria decision analysis method (Souza, 1997).Halfway through 1998, a team of researchers from the HumboldtStateUniversity at Arcata, California, launched the WAWTTAR programme (Water and Wastewater Technologies Appropriate for Reuse). At the beginning of 1999, the Research Centre of the University of Queensland, Australia published the findings of their work with the SANEX model , Appropriate Sanitation in Developing Countries: the development of a computerized decision aid (Loetscher, 1999)

Another model related to water supply and sanitation technology selection for rural and peri-urban areas (Brikké, 1996) was developed by the Operation and Maintenance Working Group of the Water Supply and Sanitation Collaborative Council. This model was developed by IRC in the Netherlands, with support from the World Health Organization WHO. In this case the methodology was based on the concept of sustainable solutions and involves four basic factors: technical, environmental, institutional and community factors.

During 1996 to 2002, CINARA, UNIVALLE, with the support from the Ministry of Economic Development of Colombia and the participation of other institutions in the sector,implemented the Technology Selection and Cost Analysis of Water Purification Systems Programme, and developed a conceptual model (Figure 1) and a computer programme, as a contribution to the efforts of the water supply and sanitation sector in Colombia to improve the impact of the investments in the sector.

Figure 1. General scheme for the technology selection conceptual model (Galvis, A. et al.,1998)

Basic concepts

The sustainability concept

It can be said that a water supply and sanitation system is sustainable when it supplies the desired level of service according to economic and environmental quality and efficiency criteria, it is financed or co-financed by the users with minimum reasonable external support and technical assistance, and is used efficiently without negative implications for the environment (Galvis, G., et al., 1997). Three strategic and independent dimensions can be identified in the search for sustainable solutions: community, environment and technology, submerged in a political, legislative and institutional context.

The general theory of systems and integrated water resources management

The concept of integrated water resource management arises from the perception that the environment is a system. Two elements interact in this concept: the supply and demand of the resource. The supply of the resource is a function of water’s natural cycle, which determines its availability in terms of quantity and quality. In turn, the demand is a function of the uses of the resource, which depends on the characteristics of the users. It is important to note that there is a direct relationship between supply and demand, given that a particular use can reduce the availability of the resource for other uses. In other words, a case could arise in which the different potential uses of water are in conflict with each other. The final objective of the integrated management of resources is indeed to regulate the relationship supply–demand in a way that it guarantees the sustainable management of water resources.

In this context, pollution control plays a leading role. The use of a water source to discharge waste brings about a reduction of the resources availability in terms of quality. This poses a threat to other possible uses of water downstream from the polluted source. In this sense, pollution can be interpreted as an increase of the system’s entropy which is apparent in the poor quality of water and thus, in the availability of the resource.

Treatment objectives

In the context of water pollution, treatment objectives refer to the efficiency of the technologies in removing contaminants. Thus, in the case of pollution originating from wastewater, the treatment objectives determine which substances should be removed and in which proportion. In this way, in a technology selection process the definition of the treatment objectives is a fundamental aspect. (see Figure 2).

Figure 2. Treatment technology selection function of wastewater origin, its constituents and treatment objectives derived from discharge criteria ( Adapted from Veenstra, 1997)

Cleaner production

The United Nations Environment Program (UNEP) defines cleaner production (CP) as “the continuous application of an integrated, preventive strategy applied to processes, products and services”, to reduce the relevant risks to human beings and the environment.

From the point of view of manufacturing processes, CP is directed towards the conservation of raw materials and energy, the elimination of toxic raw materials and the reduction of the quantity and toxicity of all contaminating emissions and waste. In the case of end products of the manufacturing process, CP seeks reducing the negative impacts that accompany the life cycle of the products, from the extraction of raw materials to the final disposal.

Technology transfer processes

There are various definitions for technology depending on the context in which it is used. In general, its meaning is associated with a tangible element, an artefact or a machine to carry out a specific task. However, technology is not only a machine. Basically it means a knowledge that can be used to produce consumer goods or a service. The concept of technology should also include a more integral vision that involves a human team, tools and tasks, since a tool has no significance if it is not related to persons and is not used to resolve specific tasks. (Visscher et al., 1997).

Technological development includes different dimensions: selection, transfer, use, adaptation, improvement and technology generation, which operate integrally in the scientific and technological development as well as in the process of transfer technology.

References

Brikke, F. ; Bredero, M. ; Veer, T. de ; Smet, J.E.M (1997). Linking technology choice with operation and maintenance for low-cost water supply and sanitation. The Hague, The Netherlands : IRC International Water and Sanitation Centre ; Geneva, Switzerland : World Health Organization (WHO) ; Geneva, Switzerland : Water Supply and Sanitation Collaborative Council (WSSCC).

Di Bernando, L (1991) Water - Supply problems and treatment technologies in developing countries of South America, Aqua, Vol. 40. No. 3, USA.

Galvis, A. ; Vargas, V. (1998). Modelo de Selección de Tecnología en el Tratamiento de Agua para Consumo Humano . Conferencia Internacional Agua y Sostenibilidad, Santiago de Cali, Colombia.

Galvis, G.; Latorre, J.; Fernandez, J.; Visscher, J. T. (1997). Multistage Filtration. A Water Treatment Technology. IRC - Cinara - Universidad del Valle. The Hague, The, Netherlands.

Loetscher, T.; Keller, J. (1997). Decisions Involving Numerous Criteria: The Example of Sanitation Planning in Developing Countries, AWM, Centre, Brisbane. Australia

Okun, D. A, (1991). Best Available Source AWWA Journal, MARCH 1991, USA.

Reid, G. W. (1982). Appropriate Methods of Treating Water and Wastewater in Developing Countries. The University of Oklahoma at Norman. Ann Arbor Science.

Souza, M.A.A. de (1997). Metodología de análisis de decisiones para seleccionar alternativas de tratamiento y uso de aguas residuales / Methodology for the decision analysis to select treatment alternatives and the use of wastewater (HDT 68). University of Brasilia. Department of Civil Engineering., Brazil. URL: http://www.cepis.org.pe/eswww/proyecto/repidisc/publica/hdt/hdt068.html (in Spanish only)

Veenstra, S.; Alaerts, G.J.; Bijtlma, S. (1998). Technology Selection for Pollution Control. En: Memorias de la Conferencia Internacional de Agua y Sostenibilidad. Agua 98. Universidad del Valle/ CINARA - IHE. Santiago de Cali, Colombia.

Veenstra, S.; Alaerts, G.J. (1997) Technology selection for pollution control. IHE International Institute for Infrastructural, Hydraulic and Environmental Engineering. Delft, The Netherlands.

Visscher, J. T., Quiroga E., Garcia M., Galvis G., (1997) De Transferir a Compartir Tecnología, Transferencia de Tecnología en el Sector de Abastecimiento de Agua y Saneamiento en Colombia, Cinara – IRC / UNESCO, Cali, Colombia.

Bibliography and additional reading

PAHO/CEPIS, dissemination pages. [website]. The objective of these pages is to contribute and support sustainable technological solutions for water treatment, through diagnostic programmes, the implementation and evaluation of pilot plants, and mass dissemination. http://www.cepis.ops-oms.org

Pérez Carrión, José M "HDT 04: Appropriate technology for water treatment”. Considers the technological situation of water supply, lists the objectives of water supply systems, assesses the technological compatibility of water supply systems with the existing level of development, and considers projects of appropriate technology for water treatment in Latin America.http://www.cepis.ops-oms.org/eswww/proyecto/repidisc/publica/hdt/hdt004.html

SelTec [website]. Cinara, UNIVALLE developed a conceptual model called SelTec for the Directorate General for Basic Water Supply and Sanitation of the Ministry of Economic Development (now ascribed to the Ministry of Environment, Housing and National Development). The model includes a computer programme that enables the simulation and application of the model. This page gives access to a demo of the software, to publications of the Cinara working group, with seat at UNIVALLE, in Cali, Colombia, and also includes publications of Latin-American and European experts. http://www.sias.gov.co/sias/Seltec/index.html

“Technical Workbook on Environmental Management Tools for Decision Analysis” Newsletter and Technical Publications. [website]. Here you can find useful tools that help with the planning and decision of technological selection. Information available only in English. http://www.unep.or.jp/ietc/Publications/techpublications/TechPub-14/index.asp.

Water supply and sanitation program PAS. [website] This page seeks to develop strategies that can contribute towards the improvement of the access to public water supply and sanitation services of low-income communities at world level, through the dissemination of lessons learned. They are supported by international organisations, among these the World Bank. http://www.wsp.org/08_Region_output.asp?Region=Latin+America+and+the+Caribbean

Contact persons

• Alberto Galvis C., sanitary engineer, MSc in industrial engineering and systems, professor at Cinara Institute, faculty of engineering, Universidad del Valle, Cali, Colombia
• Dr. Miguel R. Peña Varón. Instituto Cinara, Universidad del Valle. Cali, Colombia.
• Dr. Inés Restrepo Tarquino. Instituto Cinara, Universidad del Valle. Cali, Colombia.

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Date written: 12 September 2003
Date revised: 27 January 2003 (link update)
Author: Ing. MSc. Alberto Galvis C., Universidad del Valle, Instituto Cinara. Cali, Colombia
Reviewed by: René van Lieshout, senior professional officer at IRC International Water and Sanitation Centre, Delft, The Netherlands
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