The national scenery of sewage treatment is precarious. In most of the cities, the sewage is pumped into rivers without any treatment. This causes, besides the pollution of the rivers, serious diseases to people. The population percentage served by the sewage system in Brazil is 74%, a number far from the ideal one.

Embracing 32 cities, Rio dos Sinos is among the tenth most polluted in Brazil, occupying the fourth position according to Brazilian Institute of Geography and Statistics (IBGE). And a research developed between 2010 and 2012 by professor Fernando Spilki, in Environmental Quality program of Feevale University, showed that then main responsible for the pollution in the river is household sewage, and not the industrial or agricultural waste. 

During the study Tracking of fecal contamination in Rio dos Sinos watershed, developed in partnership with the Water Treatment and Distribution Company (Corsan), a survey was conducted in the upper and medium part of the river, in nine cities that are part of the watershed. The goal of the research was to determine the contamination levels, detecting viruses and bacterium in the river. At the end of the analysis, human and animal adenoviruses were found, revealing that the immediate problem concerning to the river contamination is the household sewage.

Only 5% of the sewage pumped into Rio dos Sinos is treated; this increases the costs of the water treatment, because the less sewage you treat, the more expensive it becomes to turn it into drinkable water. Besides, the contact of the population not connected to the treatment system with contaminated water can cause many health problems, mainly the viral gastroenteritis, caused by the fecal-oral transmission. These viruses are the second cause of death by infectious diseases in the world – they represent up to 80% of the medical attendances in the developing countries.

According to professor Spilki, there are also components of industrial origin and, comparing to 2006 data – the year of fish mortality – they are a little better than previous years, but the restriction to the quality of the water treatment is the sewage. Other factor that is also linked to pollution is that it is an agricultural area and the majority of the rural properties do not have human and animal manure management. However, this perception was also destroyed by the study: the samples collected in urban areas had higher rates of fecal contamination.

“The ideal is to organize public policies capable of treating the household sewage before it is pumped into the river. People do not need to be alarmed, because we have this knowledge. With this data, the public institutions can organize themselves to solve this problem. If there is something for people to fight for, this is sewage treatment”. Fernando Spilki, Environmental Quality program professor

Human adenovirus – they embrace more than 60 serotypes and seven species. They are important causes of infections in the respiratory system, conjunctivitis and gastroenteritis (diarrhea). It is present in the healthy population and, occasionally, causes diarrhea in immunosuppressed individuals.

Aviary/Swine/Canine/Bovine adenovirus – they cause different manifestations in animals. They are pumped into the river via fecal, because of the incorrect manure management.

Thermotolerant coliforms – presence of the E.coli bacteria, main indicator of fecal contamination in all points. The concentration is, many times, above the limit stipulated by the resolution of National Environmental Council (Conama). This data strengthens the information about the bacterial pollution of the watershed.

Metals – presence above the legislation limit of these metals: aluminum, copper, iron, manganese. Coming from industrial activities, they can also represent threat to human health and aquatic life, cause pathologies, with genotoxic and carcinogenic potential, too. 

Organic compounds - presence above the legislation limit of dichloromethane and tetrachloroethene. Coming from industrial waste, like solvent and effluent of chemical industries, high rates of those in the water can affect organisms and they are classified as potentially carcinogenic by the International Agency for Research on Cancer. 

Pesticides - lower than the minimum imposed by the legislation.

- Do not throw away solid waste directly into the river, because it helps to contaminate it permanently;

- Do not throw away solid waste through the sink, because it can clog the pipes;

- Throw away the expired medicine in specific and suitable places;

- Clean the septic tank regularly.

The study showed that the most urgent problem related to pollution in Rio dos Sinos is the household sewage. Yet, the only way of improving this situation is to treat everything that is pumped into the river. The Rio dos Sinos wathershed plan states up to 80% treated in 20 years. Therefore, public policies have to walk towards this direction.

In Novo Hamburgo, Feevale University, in partnership with Comusa - Water and Sewage Services of Novo Hamburgo - maintains a pioneer project to the sewage treatment of the city since 2012. Using technology imported from Spain, it proposes to treat sewage with floatable macrophytes plants filters. That is, to use southern cattail to purify the waste before it is thrown into Rio dos Sinos. The plants absorb impurities and inject oxygen in a natural way into sewage, besides providing a large area to fixing microorganisms that help the purification process, through filtering the roots. The goal is to treat at least 82% of the city’s sewage.