USMAN DAM TREATMENT PLANTS
There are two water treatment plants at the Usman Dam that serve the needs of the territory. The first plant has a capacity of 5000 cubic metres per hour came into operation in March 1987 while the second treatment plant, which is a mirror image of the first, followed lately 13 years after.
The treatment plants, which are in close proximity to Usman Dam, are both located in the higher altitude of the Territory and this enable the water to move by gravity from the plants to the water storage tanks. The treatment plants consist of permanent structures necessary for the following treatment processess:
Aeration – At this stage, odour is removed from the raw water by exposing it to oxygen.
Coagulation – This is the process in water treatment where chemicals are added to raw water to agglomerate all the suspended particles.
Flocculation – In this stage, the agglomerates are made to settle through water pulsations. The settled agglomerates are discharged periodically.
Rapid Filtration – This process is the removal of finer impurities that are in suspension, which were not removed during coagulation and flocculation. This is done by passing water through rapid sand filter where the micro impurities are removed.
Final Disinfection – This is the final process of water treatment where chlorine, be it gaseous or powdered, is added to the filtered water to kill micro organisms (bacteria) that survived the earlier process of the treatment before water is finally sent to the consumers.
Neutralisation – This where chemical is added to water to correct the pH level of water.
The treatment of plant is complicated by service building, which contains laboratory, control room and general office. Other building provided includes the chemical building for chemical storage and closing, a generator building and a workshop housing spare parts and tool store.