Oct 13, 2011

Sewage treatment - Harvesting

Unfortunately there is no option to get rid of water hyacinth, the only option left is to control their growth: The cleaner the water the more the growth of water hyacinths slows down. So it would be a big achievement if no sewage water gets into the tank.

Currently the government of Coimbatore is running a project to convert the open drainage system into underground systems and to direct them to the new sewage treatment plant. The announced target date is March 2012.

However Siruthuli and the 25 NGOs are having doubts if the target date will be achieved or even worse that the project will never be completed due to corruption. Their idea is to build a decentralized sewage treatment plant which collects and treats the sewage streams floating into Valankulam tank. The following steps are needed:

  • Detailed water analysis needs to be carried out over time
  • Based on the water analysis results a suitable treatment technology needs to be selected
  • A proposal with cost calculation needs to be handed in to the government
  • Grants and sponsors need to be identified
  • A company who builds the plant needs to be selected
  • The maintenance of the treatment plant needs to be established
  • Siruthuli and the other 25 NGOs are at the beginning of this process.

However the water hyacinth problem exists NOW. Actions are needed NOW so that the situation is not getting.

The only option remaining at the moment is: Harvesting. Harvesting of water hyacinth is time consuming and cost intensive.

So the big question is: HOW CAN WE MINIMIZE COSTS? HOW CAN WE MAKE THE HARVESTING PORCESS AS EFFICIENT AS POSSIBLE?

What needs to be done:

  1. Thick mats need to be separated into pieces
  2. Mat pieces needs to dragged or pushed close to the banks
  3. Water hyacinth need to be pulled out of water either manually or with help of a machine
  4. Water hyacinth need to be removed from the banks to avoid new spread.

Typical harvesting and transportation problems:

Hyacinth tends to float away, when manually harvested from banks. Due to their high percentage of water (95%) they are heavy to lift and are of high volume.

Problem through sewage contamination: due the high sewage water concentration in Valankulam tank the water is dangerous to health. Physical contact with the water needs to be avoided

Any idea, any creative thinking?

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