Low Cost Wastewater Treament Altenatives for Developing Countries

Four of the major wastewater treatment technologies that are suitable for developing countries are presented in this paper. They are: waste stabilization ponds (WSPs), wetlands, upflow anaerobic sludge blanket (UASB) reactors, and chemically enhanced primary treatment (CEPT). An introduction to each technology and advantages and drawbacks are discussed. Case studies and data from actual operating systems are presented.WSPs are large, shallow basins in which raw sewage is treated entirely by natural processes involving both algae and bacteria. WSPs are still one of the most effective non-conventional biological/bio-chemical methods of sewage treatment in developing countries especially in hot climates.Wetlands are defined as land where the water surface is near the ground surface for long enough to maintain saturated soil conditions, along with the related vegetation (hammer and bastian, 1989; Mitsch and Gosselink, 1993; Reed et al., 1995). Based on their construction, wetlands are broadly classified into natural and constructed wetlands.UASB reactors are very efficient anaerobic wastewater treatment systems, especially in tropical climates. They have hydraulic retention times of 8–12 hours when treating domestic wastewaters in warm climates.CEPT is the coagulation/flocculation of raw wastewaters with the addition of a chemical (lime, aluminum sulphate, ferric chloride, ferrous sulphate, etc.) followed by primary sedimentation.Very few wastewater treatment facilities in most developing countries work properly. Treatment systems, without considering the appropriateness of the technology for the culture, land, and climate would make these treatment systems unsustainable.The ideal wastewater treatment facilities for developing countries are the ones that could be built and operated at an affordable cost, involving less chemicals, operated without or minimal electricity, require minimal maintenance and could produce acceptable effluent quality for discharge.