Saturday, September 1, 2012

Raddolugama Water Treatment Plant

Chameera Punchihewa
28/08/2012
3rd post

Have you ever thought twice..

about the water that comes gushing out of a opened tap before you drink it, wash with it or use it for any other purpose? most people would answer this question with a 'No'.. frankly I hadn't given it much thought either.. not until the day we visited the Raddolugama Water Treatment Plant that is.

             Established in 1982 to provide safe drinking water to the residents of the Raddolugama housing scheme, the largest housing scheme in the country comprising of over 2400 houses this water treatment plant in the present day supplies 4500 m3 of water expanding its reach to the Wijaya Kumarathunga memorial hospital, the army base and police HQ of Seeduwa and the Katunayake industrial zone.
                Water is pumped from the Dandugama oya which is the main water source for the plant. the water reaching the plant undergoes various treatment processes such as ;-


  • Aeration - O2 is mixed with the water, the oxidation process leading to removal of harmful particles/ gasses from the water




  • Coagulation - addition of Chemicals such as Alum (aluminium sulphate) which combines with mud particles to form mud floccules &  Ca(OH)2 which maintains a pH of 7.0 in the water





  • Sedimentation - water is made to flow through parallel steel plates, forcing the formed mud floccules to separate and collect at the bottom of the tanks.
       A 'pulsator' type clarifier is used and the sludge formed at the  base is removed by 4 valves.


  
  • Filtration - each filter consists of 3 layers. a superficial layer of sand, middle layer of granite and the deepest layer of concrete. helps to filter out smaller particles which evaded the previous steps.                    the filtered water is next sent to 2 large Storage tanks ( 2000 m3 ) prior to chlorination.

  • Chlorination - chlorine is added until a concentration of 1mg/L is reached

  • Distribution - prior to distribution the water in its final stage is assessed once in every 2 weeks in regional labs to see if recommended Biological O2 demand (BOD), chemical O2 demand (COD), desired pH levels are reached   

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