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THE OPERATIONAL CHALLENGE
A large-scale mining operation located in the Amazon region faced a critical environmental problem. The effluents generated by the operation systematically exceeded legal standards, and the existing treatment structures were unable to reverse the situation.
Three areas contributed to the generation of contaminated effluents in the operation: the waste rock pile, the tailings pile (which stores the material resulting from ore processing), and the ROM yard with workshop area.
Each of these areas had its own constructed wetland system for effluent treatment. On paper, the system should have worked. In practice, two critical parameters were consistently outside the legal limits: total sulfate and zinc. The receiving river, classified as Class II, required compliance with CONAMA Resolution 357.
Our work involved technical field visits to all areas, analysis of two years of monitoring history from 2022 and 2023, assessment of the carrying capacity of existing wetlands, and modeling of the mixing zone at the river discharge points.
The numbers were unequivocal. For the waste rock pile wetland, the sulfate load deviation was 1,326%, meaning that the structure received thirteen times more load than it was designed to treat. For zinc, this deviation reached 5,838%.
The tailings pile showed an evolving pattern. In 2022, sulfate values were still within the limit. In 2023, the average jumped to 2,404 mg/L, indicating that the deposited material oxidized over time and increased the generation of contaminants.
Modeling of the mixing zone at the discharge points PLE-01 and PLE-03 confirmed that, even with the dilution provided by the river, the quality parameters would not be met without more robust treatment.
SOLUTION PRESENTED BY GIGWATER
Based on treatability tests conducted in our laboratory and the premises defined by the diagnosis, GIGWATER proposed an Industrial Wastewater Treatment Plant with sequential chemical precipitation. This is a process that adds chemical reagents to the effluent to transform dissolved contaminants into solids that can be separated from the water by sedimentation.
The process was structured in three stages: the first stage is the precipitation of gypsum, the second stage is the precipitation of ettringite, and the third stage is carbonation with CO₂.
SOLUTION PRESENTED BY GIGWATER
Based on treatability tests conducted in our laboratory and the premises defined by the diagnosis, GIGWATER proposed an Industrial Wastewater Treatment Plant with sequential chemical precipitation. This is a process that adds chemical reagents to the effluent to transform dissolved contaminants into solids that can be separated from the water by sedimentation.
The process was structured in three stages: the first stage is the precipitation of gypsum, the second stage is the precipitation of ettringite, and the third stage is carbonation with CO₂.
IN-DEPHT DIAGNOSIS WITH HISTORICAL DATA
ANANLYSES BASED ON REAL AND ACCURATE NUMBERS
UNDERSTANDING THE REASONS FOR FAILURES IN WETLAND
VALIDATION OF THE TCHNOLOGICAL ROUTE BEFORE INVESTMENT
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