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Uganda to construct modern treatment plant

The state-owned National Water and Sewerage Corporation (NWSC) says it intends to spend close to €70mn for the construction of a modern sewage treatment plant on the Nakivubo channel in the capital city an effort to improve the countrys old and dilapidated sewage system in the country.The state-owned National Water and Sewerage Corporation (NWSC) says it intends to spend close to €70mn for the construction of a modern sewage treatment plant on the Nakivubo channel in the capital city an effort to improve the countrys old and dilapidated sewage system in the country.

The project, to be financed by the African Development Bank (ADB), the German government and the European Union (EU), kicks off in April next year and will involve the construction of new sewage treatment plants in water catchment areas around Kampala starting with the Nakivubo plant and later Kinawataka, Nalukolongo and Lubigi.

The managing director of NWSC, Dr William Muhairwe, quoted in the local media, says the Nakivubo plant is expected to treat about 45mn litres of both sewage and water discharge per day and will be ready by 2012.

Dr Muhairwe says that for many years, the water body has not paid attention to the sewage component adding that the plants are expected to improve sanitation services from the current seven per cent of Kampala's city population to 30 per cent.

Uganda is reported to be among the least sewered countries in the world and the city presently has only one sewage treatment plant at Bugolobi on the outskirts of the capital Kampala.

A local engineer, Wycliffe Mutesasira says the national sewage line has not been developed since the colonialists left and that's why it's common to always find overflowing sewage spilling on the streets which poses a health risk to the resident.

"Most private developers have constructed their own septic tanks because they cannot connect to the national sewer line. There are only a few areas that are connected to the national sewer line and majority of Ugandans are using pit latrines because they cannot afford waterborne systems, “he says in an interview adding that the system needs a complete overhaul because the pipes are old and clogged and the sewage cannot flow while the population has increased substantially.

"At least urban centres should have a sewer line. It is very primitive for us to construct septic tanks. We should have sewer lines going through most of these urban centres," he adds.

Dr Muhairwe says the existing sewerage network will be rehabilitated through flushing or replacement where capacities have been exceeded by demand. The system will also be expanded to cover most of the Nakivubo catchment and modified to be finally connected to the Nakivubo Sewerage Treatment Works.

A state of Environment report for Uganda, 2005/06 notes that a number of towns including some district headquarters still have no water and sanitation services by the NWSC and attributes it to limited financial resources while the creation of more new districts seem to stifle efforts by the water body to extend services to these areas.

It says that latrine coverage increased from 57 per cent in 2003/04 to 58 per cent during 2005/06 although coverage is varied across the country with Rukungiri district in south western Uganda leading with 95 per cent while Kabong and Kotido districts in north eastern Uganda trail with coverage of 2 per cent each.

"During 2004/05, the corporation continued with the quest to ensure within its limits, the sewerage services were provided in an efficient and cost-effective way. To this effect, a total of 7.2 km of sewer mains and 262 new sewer connections were extended and installed. In addition, there was a reduced incidence of sewage spillages in towns served by the body."

The report says in areas where the conventional methods of human excreta disposal (through pit latrines and water borne systems) are limited, efforts are being made to expand latrine coverage by promoting the use of Ecological Sanitation (EcoSan) toilets which are suitable for in difficult situations where soils are rocky and water logged making it hard to dig pits.

National Water and Sewerage Corporation says it currently employs two types of sewage treatment systems that include Conventional Sewage Treatment Works (CSTW) and the Sewage Stabilization Ponds (SSP) and the former is only applicable at the Bugolobi Sewage Treatment Works for Kampala city and one plant in Masaka Sewage Treatment Works.

The water body says in a CSTW, there are three main stages /units for sewage treatment like preliminary sewage treatment adding that two other stages of sludge treatment, digestion and drying exist alongside waste water treatment.

Preliminary treatment deals with removal of suspended solids and organic matter in sewage by use of metallic bar screens, sand trap or detritus while primary sewage treatment is a stage where organic solids are separated from liquids, 1st sludge sedimentation tank in the same order and the sewage after removal of most of the suspended matter, flows to the second purification stage.

The water body says secondary sewage purification is by bacterial activity and the process is known as bio-filtration because the sewage flows over bacteria growing on a slime film on the surface of a well-aerated stone bed.

For Sludge treatment, the sludge removed in the sedimentation tanks is pumped into sludge digesters where its digested anaerobically and after about eight weeks, the purified sludge is pumped into sand drying beds where it is further purified while the Sewage Stabilization Ponds are a low cost sewage treatment system that uses bacterial activity to remove organic matter, nutrients and microbes in sewage.

Geoffrey Muleme

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