Mt Eriama Water Treatment Plant

Text Box: WATER TREATMENT PLANT Water Treatment Plant Mt Eriama Treatment Plant currently has the capacity to produce at least 184 Mld after the recent upgrading works. This quantity is sufficient to meet projected water demand for National Capital District up to 2020. Photo: Mt Eriama Water Treatment Plant showing the filter blocks with the clear water tanks (2) in the background Mt Eriama Treatment plant comprises of three sedimentation tanks, six boby filters and recently two additional filter blocks, two treated water storage tanks, the old control room and dozing plant, the new office building and laboratory which is supported with a standby generator set. The treatment process used are coagulation and flocculation with aluminium sulphate (alum), followed by sedimentation and filtration. Treated water is passed through chlorination stage with pH adjustment by addition of lime. Treated water is discharged into roofed clear water storage of 1.3 Ml (million litres) and 9.0 Ml respectively. Sedimentation tank in stage 1 takes place using alum coagulation with mechanical flocculation. On the other hand, stages 2 and 3 use alum coagulation with mechanical mixing and slurry recirculation. Secondary treat by rapid sand filtration is provided by six closed gravity multi-cell “boby” filters. The recent Upgrading Works included construction of two new filter blocks which have a combined capacity of handling at least 60 Mld. Chemicals Used The chemicals used for the treatment are chlorine gas, alum and hydrated lime. Alum is used as a coagulant while chlorine is used to kill germs and bacteria. Lime is added to control pH. Plant Operation The recently upgraded treatment plant is equipped with all the necessary equipment and amenities to monitor the water quality parameters on line, in the attached new laboratory as the means of self monitoring. Sampling taps are provided so that samples from any sub-treatment unit could be collected for analysis inside the laboratory. The treated water supplied from the treatment plant is hourly monitored on a 24 hour basis for pH and residual free chlorine. A pH value of 7.0—8.5 and residual free chlorine in the range of 0.5—1.5 mg/l is reported to be ensured to supplied water through the hourly monitoring. Photo: Mt Eriama Water Treatment showing the three(3) sedimentation tanks.

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