Avaliação da atividade metanogênica nos sedimentos do Reservatório de Retiro Baixo, Rio Paraopeba, em Brumadinho (MG)

Abstract

The present study aimed to evaluate the methanogenic activity, in the bottom sediment of the Retiro Baixo Hydroelectric Power Plant reservoir, after the rupture of dam I, of the Córrego do Feijão Mine in Brumadinho, which occurred on January 25, 2019. The 7 collections were carried out of sediment at the bottom of the reservoir, called campaigns, between the period of 02/01/2019 (7 days before the probable date of arrival of the tailings to the reservoir) and on 20/12/2021 (after the probable date of arrival of the tailings Assays of methanogenic activity were carried out, where acetate (1M) and formate (1M) were used as carbon source, the monitoring of the experiments was done through temporal analyzes of Chemical Oxygen Demand, CH4 concentration via chromatography gas, total solids, total volatile solids and total fixed solids in order to evaluate the behavior of acetoclastic and hydrogenotrophic methanogenic microbial activity over time. Data obtained for Campaigns 1, 2 and 3, where a Mix of collected sediments was performed, were: specific decay rate of COD C1: 0.010±0.003mg COD. L-1. mg STV-1.h-1, CH4 specific concentration: 6.59E-04 ± 9.04E-04NmolCH4.mL-1.mgSTV-1, C2: COD specific decay rate 0.011±0.002mgCOD. L-1. mg STV-1.h-1, CH4 specific concentration: 2.61E-03±1.13E-03NmolCH4.mL-1.mgSTV-1, C3: COD specific decay rate 0.011±0.0006 mgCOD. L-1. mg STV-1.h-1, specific concentration of CH4: 5.14E-04±1.16E-04 NmolCH4.mL-1.mgSTV-1.For Campaigns 4,5,6 and 7, the samples of sediment were analyzed point by point, where the results obtained were as follows: Campaign 4 specific decay rate of COD Point 1: 0.002±0.001mg COD. L-1. mg STV-1.h-1, Point 2: 0.004±0.0005 mgCOD. L-1. mg STV-1.h-1, Point 3: 0.003±0.001; Campaign 5 specific COD decay rate Point 1: 0.047±0.01mg COD. L-1. mg STV-1.h-1, Point 2: 0.032±0.01 mgCOD. L-1. mg STV-1.h-1, Point 3:0.027 ±0.003; Campaign 6 COD Point 1 specific decay rate: 0.028±0.002mg COD. L-1. mg STV-1.h-1, Point 2: 0.030±0.002mg COD. L-1. mg STV-1.h-1, Point 3: 0.032±0.004; Campaign 7 COD Point 1 specific decay rate: 0.018±0.003mg COD. L-1. mg STV-1.h-1, Point 2: 0.023±0.004mgCOD. L-1. mg STV-1.h-1, Point 3: 0.026±0.001; For the values of specific concentration of CH4 using the Gompertz model, only Campaign 5 presented adjustment to the model, the values obtained were: specific concentration of CH4, Point 1 : 9.06E-03±1.17E-03Nmol CH4.mL-1.mgSTV-1, Point 2: 1.55E-02±2.64E-03Nmol CH4.mL-1.mgSTV-1, Point 3: 1 .47E-02±1.75E-03Nmol CH4.mL-1.mgSTV-1, presenting satisfactory values for the evaluation of the methanogenic activity during the incubation period.