The proposal by the government of Amazonas to adapt to Brazilian legislation the discharge of effluents from the sanitary sewage system of Manaus into the Negro River has been worrying scientists who study the chemical and biological characteristics of the basin.
For these scientists, the Negro River does not have the capacity to self-cleanse and absorb waste, unlike what the group of specialists and consultants whose studies are supporting the project of the government of Amazonas and the water supply concessionaire Manaus Ambiental says. They also alert to the fact that the Negro River, in the medium term, will have its capacity exhausted to continue receiving sanitary effluents. For others, it is necessary to offer alternatives for the disposal of waste.
“If you take 100 liters of feces from a cistern and throw it into the Rio Negro basin, obviously the river will disperse. But it’s a small amount. Now imagine doing this constantly, every day. Multiply that amount by almost two million people, which is the population of Manaus, and find out the tons that will be thrown into the river”, says chemist Sérgio Bringel, a doctor in hydrogeochemistry of small and large rivers in the Amazon basin and a researcher at the Instituto Nacional of Research in the Amazon (Inpa).
Sérgio Bringel, who is a member of the State Council for Water Resources (CERH), is one of the biggest critics of the proposed regulation of the subfluvial outfall (sewage processing and treatment system) without in-depth research on the conditions of the river actually proving that there is a risk of pollution getting worse.
Domitila Pascoaloto, a biologist and researcher at Inpa’s Environmental Dynamics Coordination, also questions the proposal to regulate the construction of the subfluvial outfall. She says that the Rio Negro does not have a self-cleaning capacity, as it has different characteristics from other rivers. The researcher claims that his water is acidic and has different pH and temperatures.
Domitila Pascoaloto says that Rio Negro has no capacity for self-purification. Photo: Elaíze Farias
“They think that the Rio Negro has sufficient dilution capacity because they only look at its volume and flow. If it had this capacity, why would we have so much fecal coliforms on the riverbank and a very high concentration of metals coming from the factories in the Industrial District? The community in general has the right to know what the government will or can do with the main river in Manaus”, says Domitila Pascoaloto, who is also a member of the State Council for Water Resources.
Contamination
Manaus Ambiental has only two Sanitary Sewage Pre-conditioning Stations (EPC) covering the downtown areas and the Educandos neighborhood. Together, they are called EPC Centro-Educandos. They were implemented in 1975 when the water company was not yet privatized and was called Companhia de Saneamento de Manaus (Cosama). The current concessionaire says the EPCs have been recovered. It is through the EPC Centro-Educandos that the effluents are subjected to different treatment procedures and thrown into the mouth of the streams and then into the Negro River.
But, for Domitila, “several” similar stations would be needed so that the effluents would not be dumped directly into the Rio Negro basin. “Before the Negro River is turned into a latrine, they should treat and build several sanitary sewage stations,” he said.
Sérgio Bringel says that, as a member of the State Water Resources Council, he will “vote against the measure” on the subfluvial outfall. “Today we have contamination of the river that is reaching the port of Ceasa. The impacts of human waste are being noticed. This all has to do with the emissary that exists and that they want to legalize. When I see an expert saying that the water of the Rio Negro is self-cleaning, I invite him to take a bath in Amarelinho (a beach located in the Educandos neighborhood, on the banks of the Negro), to see if he accepts it”, he joked.
Sérgio Bringel considers the construction of several treatment plants to be a viable and intelligent alternative for the disposal, not only with separation of human organic waste (feces), but with chemical and biological processing.
“What I can say is that these measures are not taken in a transparent way. So far I haven’t seen any chemical data attesting that the Rio Negro does all that they say it does,” said Bringel.
prosamin
The position of the researchers is the opposite of the assessment of other specialists, for whom the Negro River has the capacity to receive sanitary effluents. This is the case of researcher Carlos Edwar, from the Federal University of Amazonas (read interview). It is based on this analysis that the government of Amazonas wants to propose the adequacy of the subfluvial outfall to the Brazilian environmental legislation. Currently, the only environmental license for the system is the one issued by the state agency, the Instituto de Proteção Ambiental do Amazonas (Ipaam).
In recent years, the government has been taking measures to dispose of sanitary sewage from housing units of the Social and Environmental Program of the Igarapés de Manaus (Prosamim). In its seven years of existence, Prosamim has already resettled more than 12,000 families who lived on the banks of streams (which were all channeled) and carried out urbanization works, through an investment of US$ 900 million with financing from the Inter-American Development Bank (IDB) and resources from the federal and state government. Currently, the sanitary sewage of the residences occurs via Pumping Stations of Sewage (EEE), a kind of crossing stations to the EPC Centro-Educandos. For specialists, this process puts a strain on EPC Educandos.
In April last year, consultants from different institutions (mostly from other regions) signed a document entitled Carta de Manaus, in which they state that “there was a consensus that it is feasible to use rivers, such as the Rio Negro, as receiving bodies of sanitary effluents, by means of treatment alternatives and release, through a subfluvial outfall, considering the self-purification in water bodies with great dilution capacity”.
The object of the specialists is to submit the decision to the norms of the national councils for the environment and water resources, among other regulations. The measure aims to expand and regulate a sewage network coverage that already exists throughout the city. In practice, the sewage system would be integrated, joining all the housing projects in the city, especially the residences in Prosamim. The Prosamim Project was sought, but he said that the matter is being dealt with by the State Secretariat for Mining, Geodiversity and Water Resources (SMGRH) and delegated to this body to pronounce.
Prosamim residences increased pressure on sanitary sewage. (Photo: Alberto César Araújo)
Change in legislation
The portal Real Amazon tried for five days to obtain official information from the government of Amazonas on the matter through the State Secretariat for Mining, Geodiversity and Water Resources (SMGRH), which is forwarding the issue within the state sphere. The report sent an email saying that experts interviewed were against the government’s proposal.
The SMRGH sent a note (without referring to the position of the opposing scientists) in which it informs that although the investments in the recovery of the Sewage Treatment Station and the construction of the river outfall have already been approved within the scope of the work of the Prosamim Management Unit and BID, only the environmental licensing for the recovery of the Sewage Treatment Station was granted by the environmental agency.
The secretariat says that “with the discussions at the State Water Resources Council, a motion will be sought to discuss the issue in the National Water Resources Council and that the same, together with the National Environment Council ( Conama) approve or include in the existing resolutions, the regulations for the environmental licensing of river outfalls, as is the case of the city of Manaus”.
The executive secretary of the State Secretariat for Mining, Geodiversity and Water Resources (SMGRH), Jane Crespo, who was also contacted, sent an email saying that a resolution by the National Council for the Environment (Conama) “wrongly” suppressed the term subfluvial outfall of the text. This situation, according to Jane, is causing discomfort for environmental licensing.
“Some seminars have already been held to understand the functioning and capacity of supplying pollutants from the Rio Negro. It is still a sensitive issue and the State Council of Water Resources is scheduling meetings in the technical chambers and in the plenary to mature the theme. The strategy we are using is to gather all possible manifestations and prepare a technical correspondence for the National Water Resources Council, in which Amazonas has an accent, so that we can correct the Resolution with Conama. We hope that by March 2014 this matter will be resolved,” he said.
Read more: “Rio Negro has the capacity to receive treated effluents”
