Pilot Project for sewage treatment launched

GANGTOK, 06 July: A pilot-project to test a simple, cheap and eco-friendly method of treating sewage utilizing a popular Japanese technology named “the Niimi Trench System” was launched last week at two sites in East Sikkim - one in a home stay belonging to Paul Rai in Pastanga and the other at Lumsey Junior High School in Upper Tadong.
Inspection of the Lumsey school site was carried out by Lok Sabha MP PD Rai on 02 July along with Deputy Mayor Shakti Singh Choudhury, ward councilor Bhaskar Basnet, School headmaster TN Bhutia, SE HRDD CK Basnet, member School Management Committee, Shumsher Subba, teachers and local Panchayat Inspectors, a press release informs.
Also present were members of the Japanese team –Kimura Hiroko and Yasuhiko Kimura from Mokan Joka (the company which had invented the technology 20 years ago), Mari Kogiso and Prof Yonekura of the Sasakawa Foundation and Ninad Kulkarni from Dalberg Global Development Advisors.  Rajendra P Gurung, CEO of Ecotourism & Conservation Society of Sikkim (ECOSS), explained the construction methodology and mechanism of the system to the visitors. ECOSS  is executing and monitoring the pilot project at the two sites.
The said that the pilot, if successful, could be used to augment the Nirmal Bharat Abhiyan sanitation programme of the state and make it more comprehensive by addressing the gaps and shortcomings in sewage treatment. The technology being very eco-friendly, would add further value to the state’s “green” programmes. He said it could be dovetailed into the current JICA funded project in the state and established as further pilots in the 11 ecotourism sites selected by the project. For this, the company is in consultation with the JICA offices in Indian and Japan. One could also look into integration with the MG NREGA programme for a cluster based approach to sewage treatment in villages, he said, adding that it could also be used for village community toilets, or for wayside tourist amenities and for schools.
THE NIIMI TRENCH SYSTEM basically utilizes microorganisms and earthworms present in local soils to treat sewage and grey water and render these safe for absorption into the soil. The soil for the septic treatment area is first tested for optimum porosity and a good rate of organic decomposition.
The system consists of a sedimentation tank, a distribution tank and two absorption trenches that are rested alternatively. The shallow trenches, around two feet deep, are lined with a base of sand covered by a plastic sheet to which a layer of sand is further added, followed by a layer of aggregate stone chips. Perforated plastic pipes of adequate length are laid horizontally on the aggregate. The pipe is further covered by more stone chips piled up in a heap. A plastic net is placed over the clinker stones and finally the trench is covered over fully by loamy earth. The sedimentation tank made of bricks is lined with a plastic sheet. Horizontal flat grill bars are placed over the sheet followed by stones, a plastic net and finally earth again.
The system is simple and easy to construct, is relatively cheap and can be made using 100% local materials. There are no gas vents and there is no odour from the tanks or trenches. The soil over the trenches can be covered with grass or made into a flower or vegetable garden. The only maintenance is seasonal switching of the trenches and occasional removal of sludge from the sedimentation tank. Niimi trench systems can last for around 20 years in the least. A similar pilot has been carried out by the company in Thimpu Bhutan.
Mokan Joka has been developing and exporting its sewage treatment systems widely across Japan, China and Korea. A larger mechanized version of the system is used to treat sewage of bigger towns and municipalities in these countries. Exploratory consultations have also been recently held with the governments of Mexico and Bhutan in this regard.