Diverting waste from landfill

A behind the scenes insight into projects that actually solve waste handling issues

In Colombo, the capital of Sri Lanka, a serious effort is being done to eliminate waste going to landfill. Meet one of the key technology suppliers to the project, Xergi A/S, which is supplying the organic waste handling facility – a complete biological processing plant for the project.

Sri Lanka is a fast expanding economy, with a population of 21 mill. It is currently experiencing a booming interest among tourists. And who can blame them, since the country offers beautiful beaches, culture, nature and wild life experiences. Waste handling, however, has not been one of the country’s strong points – until recently.

As is the case for many countries in the region, waste was not treated but ended up in ever increasing mountains of waste at the landfills in the outskirts of the cities.

Food waste collection

Landfill

The first steps towards sustainable waste handling were taken a long time before the biogas and waste handling project was commenced. In 2016 source separation of waste in the suburbs of Colombo was made mandatory. Now it is compulsory for all households, hotels, restaurants etc. in all of Colombo and its larger suburbs to segregate the organic waste from the inorganic waste.

However, still most of the waste ended up in landfills, so the government facilitated the development of an end-of-the-pipe solution, offering the waste stream – previously going into landfills – to private investors in a tender process for them to make the optimum exploitation of the resources in the waste stream, and making the necessary investments to do so.

This was the foundation for a far more environmentally friendly waste solution, where organic waste could be utilized for renewable energy production and recovery of nutrients as fertilizer.

Integrated waste handling facility

Sketch, Thumbovila Karadiyana waste management

The Thumbovila Karadiyana integrated biogas and incineration project is located in the southern outskirts of Colombo. It is currently under construction, and will handle 500 tonnes of solid waste per day once it is in commercial operation. The project will add significantly to the ever increasing demand for energy in Colombo with an electrical export to the grid of 10 MW per hour, sufficient to supply electricity for approximately 40,000 Sri Lanka households.

The key technology supplier, Xergi A/S from Denmark has been part of the project from the beginning, and is known for its leading technology for anaerobic digestion of food waste and other organic waste to produce biogas. Xergi is supplying a solution, where the organic fraction of the waste will be utilized to generate renewable electricity to the grid. Furthermore, the anaerobic digestion will not destroy the valuable nutrients in the food waste, such as phosphorus and nitrogen, but will make these nutrients available as a fertilizer for growing of new crops.

Executive Director/CTO for the project developer, Fairway Waste Management (Pvt.) Ltd., Dr. Pasad Kulatunga says; “The Thumbovila Karadiyana project marks the beginning of a new sustainable way of solid waste handling in Sri Lanka. This project will set the future standards for sustainable and environmentally friendly solid waste handling in this region.”

Environmentally sustainable solution

Biogas plant concept

Fairway Waste Management has chosen a solution, where utilizing the solid waste stream includes some of the most advanced technologies for generating energy and for making a project with a green footprint. Among these are the advanced anaerobic digestion technology from Xergi for handling of the organic solid waste, incineration technology of non-organic residual fraction, and integration of fresh liquid waste-water (leachate) from the incineration plant into the biogas plant.

Diverting waste from the landfill will not only preserve an ecologically sensitive area, it will stop ground water pollution, prevent further methane emissions into the atmosphere from the landfill, protect the wildlife, stop dust and odour pollution and prevent spread of diseases through biological vectors e.g. birds and rodents from the landfill. Importantly the biogas plant that will also treat slaughterhouse waste, which will allow the health authorities to control stray dog population, and thereby turn around the current increase in prevalence of rabies around the landfill.

The two technologies for handling the organic and the inorganic waste are key in making a sustainable integrated waste handling project. The inorganic waste can be utilized much better in the incineration plant when the wet organic fraction is treated separately, and choosing an experienced technology provider such as Xergi for handling the organic fraction makes a bankable solution.

Future trend for food waste handling

The integrated biogas and waste handling project in Sri Lanka is very much in line with the developments in the waste handling industry in other parts of the world, according to Jørgen Ballermann, CEO of Xergi: “Food waste is a core focus area for Xergi, where efficient and high performing biogas plants will extract renewable energy, while returning the nutrients to the soil to contribute to making waste handling a part of the circular economy.”

The utilization of food waste for anaerobic digestion is not a new, unproven technology. Xergi already processes large quantities of food waste at its plants in UK, France, Denmark and Sweden among others.

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