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Correct waste management would make it possible to capture polluting gases, reducing the greenhouse effect and generating electricity per year for a city with 600 thousand inhabitants

Image: Maira Heinen/Agência Brasil

The permanence of garbage dumps in Brazil and the irregular burning of waste account for about 6 million tons of greenhouse gases per year (CO2eq), according to a survey by the Economics Department of the National Union of Urban Cleaning Companies ( Selurb ). The amount is equivalent to the gas generated by 3 million gasoline-powered cars annually. The study was released on the occasion of World Environment Day, celebrated today (5) and whose theme for 2019, as defined by the United Nations (UN), is the question of “What is air pollution? Know causes and types”.

The study also identified an almost unimaginable fact: in 10 years, the damage caused to the atmosphere by the lack of proper waste treatment in Brazil will be the same as all the volcanic activity in the world in one year. “It is appalling to see how the absence of public power is capable of creating environmental problems of this proportion. Brazil has always considered itself privileged for not having to deal with natural disasters, such as those caused by volcanoes, for example. But we live with around 3,000 dumps and deficiencies in the collection of household waste that lead people living far from large cities to burn their garbage. In other words, we ended up creating a kind of 'volcano' for our atmosphere, and this is harmful to the environment and the health of the population, as the particles and substances from the burning of garbage are extremely carcinogenic to human beings”, says Carlos Rossin, Director of Sustainability and Institutional Relations at SELURB.

According to the study, the emission of gases resulting from burning garbage in irregular deposits is equivalent to the annual movement of a fleet of more than 130 thousand cars. On the other hand, the production of methane gas (CH4) from the decomposition of waste disposed in dumps, is almost equivalent to the impact of the activity of the Etna volcano, in Italy, on global warming. If this amount were converted into biogas for the production of electricity, it would be possible to supply the entire residential area of ​​a city with 600 thousand inhabitants for a year.

The survey separately analyzed the effects of different types of gas emissions. With regard to carbon dioxide, estimates were based on the formula adopted by the IPCC (Intergovernmental Panel on Climate Change), of the United Nations. According to the agency, 30% of the garbage is made up of dry residues, of which 60% are materials such as wood, paper and plastic, including residues of fossil origin. From these data, it is possible to measure the oxidation factor, which calculates the percentage of oxidized carbon when combustion occurs, discarding what remains as ash or soot.

In Brazil, according to the IBGE, it is estimated that around 7.9% of the total waste generated is burned in the population's own residence. Considering that about 78.4 million tons of waste were generated in the country in 2017, we can say that approximately 6 million tons of waste were illegally incinerated. Thus, the result was reached that the burning of garbage carried out illegally in the national territory is responsible for the annual generation of 256 thousand tons of CO2.

As for the decomposition of organic matter, the situation is even more critical, as methane gas is 28 times more impactful on global warming than carbon dioxide, according to the IPCC. Furthermore, it is a colorless and odorless gas, which increases its danger to the planet.

“One of the most worrying factors is that the production of CH4 does not stop with the interruption of irregular dumping of waste. Waste disposed of in the wrong way today may stop emitting gas for good only 30 years from now”, says economist Jonas Okawara, responsible for the study. “The calculation takes into account the accumulated amount of waste in dumps, applying the exponential correction factor to adjust the total accumulated in previous years”, explains the researcher.

Estimates are that, in 2017 alone, 29 million tons of garbage were irregularly disposed of in Brazil. The emission of methane from this illegal disposal is equivalent to 216,000 tons per year.

clean energy generation

If this amount of waste were destined for a landfill, which has the capacity and technology to transform methane into biogas, it would be possible to produce in the "climates" of the landfill's useful life the equivalent of 1.7 billion kWh per year - enough to supply electricity to a city of 600,000 inhabitants.

For experts, although alarming and serious, it is possible to mitigate the impact of gas emissions from waste.

In order for the problem to be resolved, it is necessary to promote the eradication of approximately 3 thousand existing dumps in the country and the installation of approximately 500 sanitary landfills capable of handling all waste management. After nearly 9 years of the National Solid Waste Policy (PNRS), which established the end of landfills in 2014, 53% of Brazilian cities still incorrectly dispose of garbage to clandestine dumps; the coverage of urban cleaning services (door-to-door collection) is far from universal (76%); 61.6% of the municipalities have not yet established a specific collection source to fund the activity; and the recycling rate in Brazil is no more than 3.6%. The data are from the Urban Cleaning Sustainability Index (ISLU), developed by SELURB and PwC (PricewaterhouseCoopers).

“To reverse this scenario, it is necessary to institute specific collection mechanisms to fund the operation of sanitary landfills and increase recycling and the universalization of door-to-door collection; as is the case with water, electricity, gas and telephone services. In addition to the rationalization of costs through the intelligence of scale provided by the adoption of shared solutions between municipalities”, highlights Rossin.

The solutions presented would facilitate the construction of more sanitary landfills, shared between smaller cities and a more efficient logistics so that the collected material could be disposed of with proper treatment in these structures, which could generate clean energy instead of global warming.