JICA plant will ensure faster purification, better monitoring of supply

Come May 18, many parts of Thiruvananthapuram will get clearer and purer drinking water produced at a state-of-the-art treatment plant, the likes of which Kerala has never seen before.

Seventy-four million litres of filtered and treated drinking water will flow out of this Rs.55.53-crore plant at Chithirakkunnu, Aruvikkara which uses patented technology for the production of drinking water.

At the JICA plant the raw water will first flow into a flume chamber where lime and alum will be mixed. The removal of impurities takes place in the pulsator-clarifier — a mechanism that uses a technology patented by the French company Degremont.

The suspended impurities in the water are removed by the creation of a vertical pulsating motion inside the rectangular clarifier. This pulse is triggered by the cyclical creation of vacuum inside a chamber in the centre of the clarifier.

A comparison

At the nearby 86 mld plant run by the Kerala Water Authority this function is carried out by a traditional ‘clarifier.' A huge rotating arm — called the bridge — keeps stirring the water causing the suspended impurities to settle at the bottom of the tank. This is a three-hour process. At the JICA plant the pulsators do the job is 45 minutes.

From the pulsator-clarifier the water flows to the six filter beds in the plant. Here too a patented technology reduces the time normally taken for this process. At the JICA plant the water used to wash the filter beds — the backwash process — is done through a combined action of air and water. This water too is pulsated and purified, thereby substantially reducing the ‘process loss' of water at the plant. The performance of each filter is tested every four hours.

The sludge that cannot be purified further is pumped out from a treatment plant, usually into the source of the water itself. At the JICA plant this sludge is pumped into a lagoon where it is settled and dried.

Gaseous chlorine

Another specialty of the JICA plant is the chlorine contact tank. Here, flowing water is made to repeatedly come into contact with gaseous chlorine. (This ensures better chlorination than the traditional method of mixing chlorine with water.) The water which is now potable flows to the clear water sump from where it is pumped up to the ‘break-pressure tank.' From this elevated structure water is made to flow out with the aid of gravity.

Computer holds reins

Unlike the existing treatment plants of the KWA the operations of the JICA plant can be controlled via computer. The Supervisory Control and Data Acquisition (SCADA) system located at a master control facility inside the plant allows engineers to monitor the functioning of motors, raw water pumps, pulsator-clarifiers, filter beds and the flow and pressure of water at various points.

Under the package, telemetry stations will be set up along the main transmission lines in the JICA project area. These stations along with the SCADA system will provide critical inputs to a Regional Control Centre (RCC) to be set up at the Vellayambalam campus of the KWA. The RCC can pinpoint in a flash any fault in the kilometres-long pipelines that snake through the city and the panchayats of Sreekariyam, Kudappanakkunnu and Vattiyoorkkavu.

Keywords: JICAdrinking water