low cost sanitation in tropical slums. outline background - slums and sanitation criteria for...
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Low Cost Sanitation in Tropical Slums
Outline
Background - Slums and Sanitation
Criteria for selecting sanitation technologies
Comparison of available technologies
Background: Slums
“unfit for human habitation”
“very poor”
“densely populated”
- Oxford English Dictionary
Definition:
Population increase by 58 million/year - due to rural-urban migration
890 million by 2020
Background: Slums 23 million people lifted out of slum conditions
every year (UN) A decreasing proportion of urban populations live
in slums
Background: SlumsWide variety: building materials, population density, layout, ground conditions...
Sanitation – diseases
Pathogens in excrement Transmission
Ingestion Insects Skin
Mosquito reduction important
Background: Sanitation
Objectives: Increased life expectancy Improved quality of life Poverty alleviation
Linked withHygiene educationWater supply
Selection Criteria
Health improvement Economic feasibility Technical feasibility Cultural acceptability Ownership Institutional support
Technologies
Focus: Pit latrines Simplified sewerage
Too expensive: Conventional sewerage Septic tanks Holding tanks & collection
Pit latrines: Features
Odour reduction Mosquito reduction Permeable walls $200 per unit
VIP Latrine
Pit latrines: Assessment
Cost effective Hygienic Independent of
institutional backing
Space issues
Ground issues
Water-table issues
Sullage disposal
Simplified sewerage: Features
Cheap version of conventional sewerage Narrower pipes Shallow gradient Peak flow used to clear pipes Shallower depth Fewer, simpler manholes Often combined with pour-flush toilets
Simplified sewerage: Assessment
Far cheaper than conventional sewerage
Excellent hygienically Cultural acceptability
Capital cost
Requires extensive institutional support
Sewage treatment required
Cost comparison
Source: D. Mara, Leeds University
Simplified sewerage is cheaper at high population densities
Conclusions
Slum populations are increasing due to rural-urban migration
Low cost sanitation technology plays an crucial role in improving the conditions of slum inhabitants
Sanitation must be designed to suit local requirements and implemented in conjunction with health education
Conclusions
Simplified sewerage Very high level of sanitation Most cost effective if widespread take-up
Pit latrines High level of sanitation Feasible with less institutional support
Questions?
Technologies – Toilet Design
Hole in floor
Healthimprovement
Economic feasibility
Cultural feasibility
Technical feasibility
Cistern-flush
GOOD POOR GOOD POOR
Pour-flush
GOOD VARIABLE GOOD VARIABLE
No-flush
VARIABLE GOOD POOR GOOD
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