Ecologic solutions for waste materials

Considered an environmentally correct solution for waste disposition, sanitary landfills increase their life with a massive compaction and the use of the right equipment

The disposition of waste materials is a problem that Brazil could not solve. While cities try to make feasible sanitary landfills, waste disposal areas continue to be a place of discard and will remain this way till the second half of 2021, according to the draft bill 2289/ 2015 that is being discussed in the House of Representatives. This bill extends the deadline for the municipalities dispose their waste materials in an environmentally correct way. In practice, this represents a safe-conduct for them to continue to dispose waste materials in open-sky areas with no soil protection, putting in risk the environment and the sanitation conditions.

Areas of waste disposal had to be discontinued in 2014, as determined by the National Policy of Solid Waste. The situation worsened with the increase in the quantity of waste materials generated by the Brazilian population, which passed from 78.6 million tons in 2014 to 79.9 million tons in 2015. These data came from the Associação Brasileira de Empresas de Limpeza Pública e Resíduos Especiais (Abrelpe) and are surprising since they were obtained in a time when the country was already going through a period of economic crisis.

The sustainable way to handle this problem would be reducing the generation of waste and planning an efficient selective collection, in a way to send to sanitary landfills—and never to unprotected areas—only waste materials that are not part of the recycling chain. Unlike waste disposal areas, sanitary landfills are currently the environmentally correct solution for waste disposition, with sealed soil to prevent that the slurry generated by the decomposition of waste materials could reach the groundwater table.

The place has an appropriate structure to receive waste, to confine it under layers of compacted soil and to transform it in organic materials (slurry and methane gas). “The landfill is leveled and compacted. Then it receives a thin layer of gravel, waterproofing coating and canvas”, explains Gleidson Gonzaga, product expert from Case CE, manufacturer of the crawler tractor 2050M whose production started last year in Brazil. “Only after this preparation the area will be able to receive the several layers of garbage and soil, being constantly compacted. When it reaches a determined height, drains for removal of slurry and methane gas will be built. These products have specific destinations in accordance with the design of the landfill”, tells the expert. He also tells that usually the slurry is sent to a pond built in the place and then goes to treatment plants where it is transformed in water used for specific purposes such as dust containment in roads.

In the same way, methane gas cannot be liberated directly to the atmosphere. It has to pass through a combustion process to become less aggressive to the environment. According to the operating engineer of the sanitary landfill from Recicle Catarinense, Galdino Eloi Savi, the contamination will be 21 times higher if the gas is released without being burnt. “Some experiments carried out in the Federal University of Santa Catarina suggest to use the methane generated in Recicle’s landfill for power generation to drive the aerators of the slurry treatment plant”, explains him.

TRANSITION

Savi believes that Brazil is going to end its sanitary landfills—mainly in the region of Santa Catarina—due to the difficulty to obtain environmental licensing of areas for this purpose. “With the end of municipal disposal areas, the current way is to get licenses for regional landfills—that will be used by several cities—or use intercity consortiums. Therefore, there will be no sanitary landfills at the end of the next 15 years”, emphasizes him. “The few landfills that will remain will be used only for organic materials with no attractive commercial value. Incinerators will also be used, as procedures currently used in countries such as Germany, for example.”

Gonzaga, from Case, disagrees. “Waste disposal areas will be eliminated for the benefit of life quality and environment. At least 500 sanitary landfills will be created in Brazil until 2020”, estimates him, based on the need of compliance from the municipalities. He also says that some areas are licensed for up to 30 years and engineering teams carry out several projections based on the quantity of waste received. “I believe that—before carrying out Germanic-type solutions—Brazil will have a transition period when regular sanitary landfills will be the sustainable way for waste disposition. After the next 30 years, the country will be prepared to handle waste correctly and to have a lower dependence from landfills. But there is a long way to run”, says the engineer.

There are few sanitary landfills in countries such as Germany, Luxembourg, Belgium, Holland, Denmark, Sweden and Norway. Most waste materials are incinerated. In some places, landfills are used eventually in the case of stoppage of incineration plants or for destination of the ashes resulting from the burning process. According to Detlev Wickert, product manager of waste compactors from Bomag, some landfills operate with inert residues in Europe. “But France, Eastern Europe and parts of the Southern Europe have few incinerators due to their high cost”, explains him. “Waste generated in these plants goes to sanitary landfills.”

Due to this reason, sales of specific equipment for sanitary landfills decreased. “The countries of Eastern Europe continue to use them regularly because this region has an intense activity turned to waste management”, tells Wickert. “But the biggest markets for these machines still are Europe and USA.”