5 months ago


Water treatment

2.11 Research

2.11 Research Objectives, Approach and Hypotheses The overall objective of the present research work is: • To contribute to the understanding and development of multistage filtration (MSF), as an innovative, robust and efficient water treatment technology for small to medium size water supply systems and to develope a treatment technology which is able to deal with surface water sources characterised by wide-ranging levels of contamination and abrupt water quality changes. The specific objectives of the present research work are: • To identify the levels of contamination associated with representative rivers in the Andean Cauca Valley (ACV) with respect to physicochemical and microbiological guidelines included the basic parameters presented in table 2.3. • To evaluate the removal efficiencies of different CMF alternatives under different operating conditions and working in series with SSF with respect to basic drinking water quality parameters. • To make comparative analysis of different combinations of CMF alternatives working in series with SSF with respect to removal efficiencies and O&M requirements. • To contribute to solve or clarify some of the points of discussion about design, operation or maintenance of the CMF alternatives summarised at the end of sections 2.8.3, 2.8.4, and 2.8.6. • To develop selection criteria for the best options of the MSF technology based on performance objectives and some considerations on capital and operating costs in the ACV. The overall approach of the present research work includes: • Short term tests on bench scale pilot units treating water from high and lowland rivers of the ACV. • Medium term tests on pilot scale units treating water from a lowland river of the ACV • Long term monitoring of full-scale plants treating water from highland rivers of the ACV. • The gradual construction of a learning environment between local caretakers, community-based organisations, national and international advisors, and staff of the Cinara Institute of the Universidad del Valle, to gain experience from each other throghout the research and development process. The general hypotheses behind the present research work were: • Depending on ranges of pollution level in the raw water sources there are better options of the MSF technology to produce water that meets water quality criteria for basic physicochemical and microbiological parameters, without recourse to chemical coagulants. • Basic treatment objectives of

3 MULTISTAGE FILTRATION STUDIES WITH PILOT SCALE SYSTEMS 3.1 Materials and Methods 3.1.1 Study area The research activities with pilot unit systems were developed in Cali, the capital city of the Cauca Valley Department, which includes a major part of the Andean Cauca Valley. This department is located in the west part of Colombia, as illustrated in figure 3.1. The mean width of the flat area of the valley is 30 km in the south and 10 km in the north. This flat area is located between the western and central chain of mountains of Colombia, at 900 to 1100 m above the sea level. The mean temperature in this area is 24 ºC with changes in the range of 10 to 38ºC. Two rainy periods can be distinguished in the Cauca Valley (April-May and October-November), discharging almost 70% of the annual precipitation, and two dry periods (January-February and July-August). The average annual precipitation is 1000 mm in the flat area of the valley and 1800 mm in the hillsides (figure 3.2). The average monthly humidity is usually in the range 70 to 75%, in spite of the rainfall variation throughout the year (Alzate- Castaño, 1994; CVC, 1998). Figure 3.1 Location of the Cauca Valley Department in Colombia, South America. 69