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URBAN WASTE MANAGEMNT AND UNDERGROUND WATER QUALITY IN COTONOU TOWN IN REPUBLIC OF BENIN

URBAN WASTE MANAGEMNT AND UNDERGROUND WATER QUALITY IN COTONOU TOWN IN REPUBLIC OF BENIN. Dr. Henri Soclo Universite Nationale du Benin. BENIN. Cotonou, Benin. Background. Cotonou = economic capital of Benin Geography From coastline to the Cotonou lagoon

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URBAN WASTE MANAGEMNT AND UNDERGROUND WATER QUALITY IN COTONOU TOWN IN REPUBLIC OF BENIN

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  1. URBAN WASTE MANAGEMNT AND UNDERGROUND WATER QUALITY IN COTONOU TOWN IN REPUBLIC OF BENIN Dr. Henri Soclo Universite Nationale du Benin

  2. BENIN

  3. Cotonou, Benin

  4. Background • Cotonou = economic capital of Benin • Geography • From coastline to the Cotonou lagoon • 6°15’ - 6°20’ N / 2°21’36’’ - 2°37’ E • Elevations of 0.3 - 6 meters amsl. • Surface Area = 7,000 hectares • Population • 553,000 in 1992 • Currently ~1 million inhabitants

  5. Basic Groundwater Hydrology • Flooding related to shallow water table. • Groundwater flow is from the central region to • The lagoon system to the North • The littoral border in the South. • Groundwater is bacteriologically and chemically contaminated by solid and liquid household wastes • Problem exacerbated in peri-urban zones • diarrhea, cholera, and typhoid fever

  6. Basis of Problem: Solid Wastes • 1400 mm of precipitation • Flooding: March-July / Sept.-Nov rainy seasons • ~ 0.45 kg per person per day = ~ 400,000 tons a year in 1998 • Only 30% is collected and treated • 70% • thrown on streets • buried • used for embankments

  7. Characterization Effort • 29 Wells • All Hand Dug (<4 meters depth / 0.5-2 m diameter) • Divided by regions • 1- Good collection of domestic waste • 2- Low level collection of domestic waste • 3- No collection of domestic waste • 4- Marshy areas • 5- Industrial sites • 6- Sites near the lagoon (within 1 km) • 7- Sites with impact from the ocean (within 1 km)

  8. CHEMICAL CHARACTERISTICS Temperature pH conductivity NO3-, NO2- SO42- HCO3- Sodium Potassium Calcium magnesium heavy metals for organics, BOD BACTERIAL TESTS EMB, WILSON, GLD, CHAPMAN and TSN culture media used to quantify Eschrichia coli Salmonella Enterobacter Staphylococcus Sulphate reductor Clostridium, MAC Conkey and Azide Esculine Bile were used detect coliforms faecal streptococcus. Sample Parameters / Bacteria

  9. Bacteria versus Collection Zone 200 1 = High Level Waste 2 = Medium Level Waste 3 = Low Level Waste 150 "TOTAL GERMS" per ml 100 50 0 0 1 2 3 4 5

  10. Nitrate versus Collection Zone 250 1 = High Level Waste 2 = Medium Level Waste 3 = Low Level Waste 200 150 Nitrate in mg/l 100 50 0 0 1 2 3 4 5

  11. Metals Near Marsh Areas 6 4 = Marsh Areas 6 = Lagoons 7 = Oceans 9 = Other 5 4 Cadmium mg/l 3 WHO - 5 mg/l 2 1 0 3 5 7 8 9 10 4 6

  12. Observations • Microbes • Dramatic Evidence of Widespread Contamination • Nitrates • Consistently High Throughout Region • Metals • Consistently High In Marsh Regions • ALL INCREASING WITH TIME • Greatest Immediate Concern is Bacterial Contamination in Wells

  13. Possible Solution for Biological Threat • To reduce epidemic risks in these zones • chlorine diffuser pots in local wells • allows microbiological treatment • inexpensive treatment method • available to the majority of the population.

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