Water Treatment Plant & Sewage System....

Sanduni Dhanoddya Samarajeewa

28 August  2012

Post – 3

On  28^th August 2012 we were supposed to visit Water Treatment Plant & Sewage System at Raddoluwa. The scope of the visit is to get an idea about the process of water purification prior to distribution.

The programme was commenced with brief introduction of the water treatment plant. The narrator explained that it was established during 1987 with the aim of supplying water to the housing scheme. At present it supplies 4500m² of water to following locations.

1.  2481 house in the scheme 
2.  2500 houses out of the scheme
3.  Wijaya Kumarathunga memorial hospital
4.  Police station and Army Base Seeduwa
5.  Katunayaka industrial zone

  Then we stepped out to witness the water treatment plant. Initially water is pumped to the plant from Dandugan Oya. After that the narrator briefed the activities taking place after pumping.

Aeration: during this process water is turn around in the air to mix with O_2.For this, Cascade method, Disk and Mechanical methods are used.

                                               

During this they add "Alam" (AlSO₄) -  It positively charged and combined with negatively charged mud particles and forms mud floccules. Then add Ca(OH)₂  - It corrects pH value  to 7. 0.

Sedimentation: during this process mud and other particles are separated. 

  
Filtering: Raddoluwa plant has 2 units of rapid sand constant head filters. It filtered the water by sand filters.

Storage:  Mud free and filtered water comes to two large tanks which has the capacity of 2000m² each. Storage tanks are covered by granite chips to avoid direct sun light.

Chlorination:  Water disinfected by Chlorine (Cl₂) in the storage tanks.

Distribution:  after all these proceedings water pumps to towers and then it is distributed to houses.

Then the narrator begins with the details of water sewage plant. She told, in the sewage plant basically waste water coming from houses is cleaned.  Initially the sewage collects in to pits called gully. Then it drains in to main man hole and it drains in to sewage well. Then it is pumped via aluminum bars by three pumps. Then it’s go to a aerator and supply O₂ for bacterial activity. Then during the sedimentation the degrading process occur.

                During the chlorination, dried material pumped in to drying lagoon to dry under sun light and the important thing is they distribute it free as fertilizer. Now the disinfected water is ready to release in to the river.

These proceedings are seems to be very easy when somebody go through this. But it is not that…..