A polluted river is a reservoir of water that during its course has received chemical, biological or even physical residue causing harm to the soil, fauna, flora or human life.
Almost at a catastrophic level, Brazilian bays and rivers are subject to countless illegal polluting sources, such as domestic sewage and industrial effluents. Pesticides, fertilizers, trash and mercury are being emptied into rivers.
The 2016 Olympics are going to be held in Brazil and Rio de Janeiro has the big challenge of making Guanabara Bay which will be used for the sailing events during the Olympics clean enough for purpose. The Bay offers the kind of postcard image of Rio, that authorities want to show while hosting the 2016 Summer Olympics however, Rio’s polluted waters have turned into frustration with the troubled preparations for the Olympics.
Even though the bay is considered to be at Olympic Games standards already, the town hall has already backed out from the promise to clean 80% of the bay water before the event.
Most Common Types of pollutants
The sewage treatment stations only partially met the original planned service goals, where each municipality is responsible for its sewage treatment. Nowadays, only 39% of Brazilian sewage receives this treatment. In addition, the sewage system only reduces pollutant loads that come from set sources like industries residues that can easily be identified, but not from diffuse sources where there is no fixed point of pollution and can happen anytime, like the infiltration of agrotoxic.
Water quality has being getting worse in terms of organic pollution over the years. The increased growth of algae contributes significantly to the increase of the problem, threatening the water quality of the entire river.
Soil has also been contaminated with heavy metals such as petroleum hydrocarbons, by the infinite numbers of industries around the bays and rivers.
How pollution is measured
Water quality is represented by a variety of features generally measured by chemical, physical and biological range. The physical and chemical characteristics of water should be kept within certain limits, which are represented by standards and guides of water quality values.
Water treatment stations complete a monthly water quality test, monitoring the station efficiency with three main parameters. They are the turbidity, the amount of floating solids and the biochemical oxygen demand, indicated by the amount of organic matter in water. This is done at the waters entrance and exit points to compare the output of the process that should be at least 80% cleaner at the exit.
Methods for cleaning rivers
Each state have their own projects for cleaning their local rivers. Below are the most common methods used in the last few years.
Ecoboats are special boats designed to clean floating residue from rivers and bays. After determining the areas with the most residue, the boats collect the trash and then take it to recycling stations. In one year alone 10 ecoboats can collect 45 tons of residue. The cost of this service was BRL 1,5 million in the first year but has since increased to BRL 1,8 million per year.
These are floating structures made from recycled materials such as plastic bottles and plastic containers designed to restrain floating garbage flowing into the rivers. Unfortunately, many of them are not resistible enough for many items found in the rivers such as mattresses and even couches. However, they are built to collect around 300 tons of solid residue per month.
UTRs - Unities of River Treatment
UTRs are specialized units for cleaning solid residue from water with an Electro Thermal Deactivation system. There are only a few of these units available to clean river waters, avoiding adding new sewer to the water.
Most polluted rivers in Brazil
Unfortunately, Brazil has not taken much care of the water quality in its rivers in the last few decades. The fast growth of cities without adequate urban planning has resulted in trash, sewage and industrial waste ending up in the rivers resulting in the death of many important water sources.
1.Rio Tietê, State of São Paulo
The Tietê is 1.136 kilometers long and intersects the state of São Paulo from East to West. In the capital, the river runs adjacent to the Marginal Tietê which is the most important access road in the city and carries two million cars per day. This area is economically important but all the attention is drawn to the environmental problems that surround the river. Projects to clean it have been in practice since 1992 with little success as parts of the river are considered dead due to a lack of oxygen in the water.
2.Rio Iguaçu, State of Paraná
The Iguaçu is an affluent river that starts in Paraná and is the largest river in the state. It is 1.320 kilometers long and shares the border with Argentina. In the municipality of Foz do Iguaçu the river has the biggest waterfalls in terms of water volume on the planet. They are called Cataratas do Iguaçu. In 2000, Petrobrás leaked 4 million liters of oil into the river, causing an environmental disaster.
3.Rio Ipojuca, State of Pernambuco
Ipojuca actually means ‘water from rotten roots’ in a native language called Tupi. The river flows through more than 12 municipalities that leak large amounts of industrial pollutants into it. This high amount of domestic and industrial debris makes Ipujoca the third most polluted river in Brazil.
4.Rio dos Sinos, State of Rio Grande do Sul
The Rio dos Sinos supplies more than 1.3 million citizens. Most of its pollution comes from human negligence with garbage, sewage and water waste, but also a lot of industrial waste and agricultural irrigation uses the river supplies. In 2006, an environmental disaster killed at least one million fish during the spawning and reproduction season. This became the biggest environmental disaster in Rio Grande do Sul in the last 40 years.
5.Rio Gravataí, State of Rio Grande do Sul
The Rio Gravataí is responsible for maintaining the water supply for the population, irrigation of rice fields, dilution of domestic sewage and industrial effluents. It is 34 kilometers long and 1 million people depend on it. This water source is the main sponsor for the development of the entire region.
6.Rio das Velhas, State of Minas Gerais
The Rios das Velhas was historically used when Brazil was a colony to transport gold between cities. Nowadays, part of the water is taken by water treatment stations and the rest receives a large amount of sewage. The environmental degradation combined with a large amount of iron ore turned a section of it into what is known as “red waters” where almost no life is present.
7.Rio Capibaribe, State of Pernambuco
Rio Capibaribe comes from the old native language of Tupi and means River of Capybaras. It is 240 kilometers long and has more than 74 tributaries that feed into it. Its mouth comes from the Atlantic Ocean and the river’s lowlands were where the first sugar cane crops were established. Nowadays, the possibility to enable public transportation through the river is being studied.
8.Rio Caí, State of Rio Grande do Sul
With an area of 5.027 square kilometers, its watershed occupy 1,79% of the state surface. Most of its pollution comes from the large presence of industries in the area, especially the branch of production from metallurgy and mechanical companies.
9.Rio Paraíba do Sul, States of São Paulo, Rio de Janeiro and Minas Gerais
The Rio Paraíba do Sul is 1.120 kilometers long and goes through an important region known as Vale do Paraiba, which is a very important economical area of Brazil, responsible for a big part of the country’s GDP. Among the pollutants are industrial waste, cattle raising and agriculture offscouring. There is also damage caused by sand mining, which alters the course of the river and lowers the riparian forests, causing sedimentation and contributing to lower navigability.
10.Rio Doce, State of Minas Gerais
The Rio Doce is 853 kilometers long and drains the states of Espírito Santo and Minas Gerais, becoming the most important watershed fully included in the Southeast region of the country. The current degradations of the river are the result of chemical contamination of industries and pesticides or herbicides from farms, threatening the health of the citizens.