Estudo de cenários econômico e tecnológico para alternativas de drenagem e tratamento de lixiviados de um aterro sanitário

Abstract

Monitoring the leachate generated in landfills is necessary, taking into consideration this liquid effluent should not be sent to water bodies in its raw form, which would cause surface and groundwater contamination, fauna and flora degradation, together with making the water unsuitable for human use. Therefore, the aim of this study was to evaluate the leachate generated in the landfill of the city of São Leopoldo and the disposal of the solid waste in six operational phases, which the effluent originated from. Also, through laboratory tests, 20 physic-chemical parameters were assessed, which enabled monitoring the area surrounding the landfill and performing the multivariate statistical analysis with the leachate samples. Finally, it was aimed to identify the financial viability through the establishment of four scenarios regarding the leachate storage and treatment, varying the leachate origin and the treatment site, assessing the costs and revenues in each scenario, enabling the financial assessment of the proposed changes. In Scenario 1, the current situation was identified, while in Scenario 2, the implementation of the Leachate Treatment Plant (LTP) was suggested. In Scenario 3, in addition to the implementation of the LTP, the separation of the leachate generated in each phase was adopted and in Scenario 4, the hypothesis was created that leachate generated in older phases would be forwarded directly to Phase 4, with the treatment carried out only by Nanofiltration and Reverse Osmosis. The monitoring of solid waste identified that more than 90% of it comes from municipal waste collection and, from the total amount of waste received at the landfill, 45% were made of putrescible solid waste, 24% of biological contaminants and 31% of recyclable material, making evident the possibility of implementation of a waste sorting facility at the landfill. Regarding the leachate analysis, 20 parameters were evaluated and, through Principal Component Analysis, it was possible to identify that the first three components (PC1, PC2 and PC3) had results referring to 69% and 82% of variance from the original data, showing the statistical difference between the phases, being the most representative ones Bicarbonate Alkalinity, True Color, Organic Nitrogen, Precipitation, Color, Ammoniacal Nitrogen, Total Organic Carbon, and BOD. Regarding the financial analysis of the proposed scenarios, all scenarios created were profitable, including scenario 4, which it is the most profitable among all scenarios, where the leachate generated in each stage is stored separately and its treatment is made in the landfill, assessing revenues and costs, it was identified that, with a 10% investment return rate, there would be a 90% profitability rate and a 7.3 months investment return time. Therefore, in addition to the positive environmental factors of the treatment plant on site, the financial viability of the scenario with the proposed changes suggests to be favorable.