The Truth About Dams in Minas Gerais, Brazil

There are multiple kind of dams in Brazil. Some are used to hold water, some to generate energy and some to hold industrial and mining waste. The variety of dams reflect their conditions: many dams are in poor shape while some maintain low risk to the environment and the people living near it.

The mining waste dams are notorious for their relevant environmental impact. Even though technology has progressed, it is known that companies in the states of Minas Gerais in Brazil prefer not to employ the new findings. The reason is the same of always: to keep their profits as high as possible.

Brazil itself lacks a system that has deep information on these dams. When a catastrophe happens, like the ones in Brumadinho and Mariana, the government officials feel unprepared and have to collect information on the spot to help the people affected by the spilling.

The state of Minas Gerais does have a system for the registration of dams and their conditions. When the requirements are not met in the reports, the officials communicate the dam owners what they need to do in order to keep their dams safe to the environment.

The following study from 2008 uses a methodology proposed by Menescal et al in 2001 which was adapted for mining waste dams. The results are as follows:

· Most of the dams with high hazard potentials were the ones with the lowest retention volumes of waste;

· The most common method for the growth of the dams is the upstream one, which is also the cheapest of all of them;

· Most of the dams presented adequate (yet still dangerous given their volumes of retention and locations in the region) results of percolation, deformation and deterioration;

· Over 60% of the dams hold high volumes of waste;

· About 76% of the dams have population spots downstream;

· About 30% of the dams need extra examination and attention from the owners and authorities;
About 48% of the dams in working conditions showed a high hazard potential and 51% had worse results;

Comments

Photovoltaics: Band Diagram

In the previous post we discussed silicon, which is the most used material in photovoltaics. In this post, we introduce the band diagram, for which we will use silicon as an example. We will start our discussion of the band diagram with the Bohr model of the silicon atom. In semiconductor materials the outer shell of the atom, which is called the valence shell, is not completely filled. The outer shell of silicon contains 4 out of the possible 8 electrons, which we call valence electrons. As we discussed in the previous post, each silicon atom in a crystalline structure is bonded to four other silicon atoms. The bonds between the silicon atoms are called covalent bonds. These bonds actually consist of two valence electrons that are shared by two silicon atoms. All valence electrons are fixed in the lattice, forming covalent bonds, and are therefore immobile. However, at a temperature above absolute zero, thermal energy is supplied to these miconductor and some of the vale

Solar Cells Losses and Design Part 1

We have discussed some important properties of light and characteristics of the radiation of light by our sun. In this post, we will focus on converting that light to electrical energy. This is done using the photovoltaic effect. Photovoltaics covers the direct conversion of sunlight into electrical energy, by a semiconductor material. The term photovoltaics is derived from the Greek word ‘phos’ which means light, and volt, which refers to electricity, specifically voltage. Volt is a reference to the Italian physicist Alessandro Volta, who invented the battery photovoltaic effect that was discovered in 1839, by the French physicist Emond Becquerel. At the age of 19 Becquerel created the first photovoltaic cell by illuminating platinum electrodes, coated with silver chloride in an acid solution. This device was the first to convert light into electricity. The photovoltaic effect occurs through the generation of a potential difference at the junction of two different material

Black Carbon is Found in the Amazon River after Forest Fires

In addition to the tracks of destruction in the forest, the fires in the Amazon leave traces in the Amazon River and its tributaries. Incomplete burning of tree wood results in the production of a type of carbon - known as black carbon - that reaches Amazonian waters in the forms of charcoal and soot and is transported to the Atlantic Ocean as dissolved organic carbon. An international group of researchers quantified and characterized, for the first time, the black carbon that flows through the Amazon River. The results of the study, published in Nature Communications magazine, showed that most of the material transferred to the ocean is "young," suggesting that it was produced by recent forest fires. "We found through radiometric dating analysis [a method that uses the radioisotope of natural carbon-14 occurrence to determine the age of carbonaceous materials up to about 60,000 years] and molecular composition that the largest proportion of the black carbon we found

The Environmental Engineering Hub

Search This Blog