Waste-gobbling stomach that holds much and churns out much more Jayasekara Hettiarachchige Kumudini Hettiarachchi

The inventor of a tried and tested compact biogas plant discusses his cost-effective baby with

It is usually food waste, but for Jayasekara Hettiarachchige Srimal Tissera, not only fats and oils but also water-hyacinth and salvinia are good enough to feed the ravenous “artificial stomach” that he has invented.

The “feed” does not cost money, for in many cases it is what people throw away such as fruit waste, vegetable waste, market waste, bakery waste, home waste or any organic matter that goes into the artificial stomach, with what comes out bringing savings and benefits.

The artificial stomach, the “baby” of Mr. Tissera, is a compact biogas plant already being tried and tested in many homes, factories, companies, hotels and universities totalling around 35.

Of a morning on a week day, the Sunday Times is in the backyard of ACL Cables Plc in Madapatha, Piliyandala gazing up at a 5,000-litre biogas digester.

The company’s Electrical Engineer Arunajith Perera who is also its Environmental Representative explains the benefits that they have derived by installing the digester, the biogas from which has helped the canteen to cut down on the LP gas usage daily when preparing meals for

After the construction of the bio-digester, to set off the activation he adds cow-dung. Usually cow-dung has low-calorie digestive anaerobic bacteria and to make them highcalorie digestive bacteria, he puts in the culture he has developed using ayurvedic medicine and herbal extracts.

This self-made scientist who had studied at Thurston College, Colombo, compares it to an artificial digestive system. Pointing out that it is underwater and in the digestive systems of animals that anaerobic life is found, he explains that he has produced different anaerobic bacteria cultures for different raw materials such as food waste, fats and oils, water hyacinth and salvinia used in his inventions.

He declines to give the composition as he is concerned about the copy-cat syndrome which ails Sri Lankans who use others’ work to gain fame.

Thereafter, with food waste, fats and oils, water hyacinth or salvinia being fed, the biogas production begins. Depending on where the biogas digester has been installed, the time of first production varies, says Mr. Tissera, explaining that in Pannipitiya it was just three days, in Batticaloa four, Anuradhapura a week and Kandy two weeks “most probably because of the different climates in which the cowdung has been”.

Like in the human digestive system, sometimes there can arise an increase in the acidity causing gastritis. “Then there is a simple solution like taking digene which is aluminium hydroxide – boiling some aralu, bulu, nelli with some pathpadagam and pouring that water in. Another option is alu hunu or calcium hydroxide.”

The biogas is 35% carbon dioxide and 65% methane, he says, adding that there is also the production of about 2% hydrogen sulfide which gives the odour of rotten eggs. To prevent this forming ferrous sulfide after reacting with the iron burner which would lead to rusting, he has also fitted a filter to reduce large amounts of hydrogen sulfide being released.

Mr. Tissera sees as the major difference between his invention and the conventional ones the fact that the latter plants have been built underground, without taking into consideration the climate of Sri Lanka; non-comprehension of the requirements for the growth of anaerobic bacteria and the misconception that only cow-dung is essential for the production of bio-gas. “They have transported foreign ideas but not localized them,” he alleges, adding that this is third class treatment for Sri Lankans. From the conventional underground systems that were installed in the 1970s only a few remain in working condition and that too not very successfully.

Refuting allegations that he himself has made a carbon copy of a plant found elsewhere in the world, Mr. Tissera challenges any of these so-called biogas specialists to discuss the technology he uses.

Stressing that he has visited plants and gained knowledge in India, Vietnam and Thailand, he says that the structure may be similar but the “technology is totally different”. This is unconventional chemistry, so people in important places don’t like it.

Ever-lasting technology, is how Mr. Tissera calls his invention, adding that the artificial stomach has only to be fed. Biogas thus produced can be used for cooking in homes, lighting of lamps on the same principle as petromax lamps and even the operation of crematoriums sans electricity

Although the installation cost for a 1,000litre plant would be about Rs. 62,000, everything you do with LP gas is possible with biogas as well as more benefits and less harm to the environment, adds Mr. Tissera.

The examples are many. The Ragama Medical Faculty uses one plant to cook hoppers from 10 kilos of flour daily, a private company in Mattakkuliya uses two plants to prepare two meals and tea for 80 people daily and also boil water and Kelani Cables for cooking in its canteen, with the list including the Ayurvedic Research Institute at Nawinna and the People-in-Need nongovernmental organization at Batticaloa. (Srimal Tissera may be contacted on

email: tisserajhs@gmail.com)