Friday, December 6, 2013
- Inspired by their success with converting tonnes of city garbage into organic fertiliser and bio gas, Sri Lankan scientists are now setting their sights on something bigger.
A bio gas plant in a large marshy swamp that would convert the unlimited resource of garbage, weeds and water hyacinth into energy is the new plan in the pipeline.
“We hope to start a large bio gas project in the Muthurajawella swampland which would help to clear the garbage in many other municipal council areas,” said Minister of Science and Technology Batty Weerakoon.
Muthurajawella, a large wetland area lying a few km outside the capital city Colombo, is an expanse of swamp, filled-up land, a lagoon, mangroves and a haven for scores of birds. It is also a protected sanctuary.
Weerakoon, speaking at a function in Colombo on Wednesday to launch new indigenously devised garbage digester units in the capital, said that the Muthurajawela programme will involve the revival of the city’s disused network of canals.
The canals that surround the swamp will be used to transport garbage from other municipalities to the bio gas plant, according to project plans.
The minister said the government was hoping to get financial and technical assistance from the Netherlands for its efforts to revive the disused canal network.
For many years, the authorities have been trying to revive the canal network, built by the Dutch during colonial times, as an alternative to the city’s congested roads. The canals have not been used for decades and are choked with silt and factory waste.
This week Sri Lanka’s first bio gas digester for the disposal of garbage from the city’s vegetable markets was launched.
Apart from being a safe and productive way of disposing garbage, the digesters produce bio gas, which can be used for domestic cooking and power generation, and organic fertiliser.
The bio gas unit – which has five digesters – feeds on garbage, straw, water hyacinth and salvinia. Each unit has a capacity of 40 metric tonnes of vegetable waste which in turn converts into one cubic metre of bio gas.
More than 700 metric tonnes of garbage is collected daily from the Sri Lankan capital and disposed of through landfills or incineration.
Sri Lankan President Chandrika Kumaratunga, also present at the launch, said that the novel garbage converter concept would eliminate the growing problem of garbage collection in the capital and other urban areas.
She said that garbage collection and disposal was currently an environmental and health hazard.
“We have been struggling with waste-disposal sites because all the filled-up and abandoned land have been utilised,” the president said.
Praising the new garbage disposal initiatives she observed that “mosquitoes and disease are rampant in the city. In the present-day context, it is illogical to use landfills and incinerators to get rid of garbage.”
The digesters were created and installed by Sri Lanka’s National Engineering Research and Development (NERD) Centre, the country’s premier institute for alternate sources of energy and the development of cost-effective building methods.
NERD has installed dozens of smaller bio gas units across the country for small industry and household use.
It has also developed low cost housing units, electronic teaching aids, solar distillation for drinking water, cheap paddy hulling for small farmers, bakery ovens and wind mills.
NEERD has received international praise and an award at the international inventors exhibition in Geneva in 1996 for the development of the bio gas digestion unit.
Earlier it built a 300-tonne digester unit in NERD’s own backyard as a pilot project before installing the digester units in the city.
NERD scientists say that the NERD centre’s experimental bio gas unit has yielded gas over a two-year period.
The digested material is found to be an excellent organic
fertilizer with reasonable nitrogen, phosphorous and potassium balance and micronutrients better than compost.
After four months of anaerobic digestion, the market garbage is biologically converted into bio fertiliser.
The method is simple: each of the five digesters, installed under the garbage converter project, is loaded with 40 metric tonnes of market garbage, which after a retention of four months would yield 25 metric tonnes of fertiliser.
Sri Lanka’s garbage disposal systems could be a model for others.