Avaliação de cargas poluidoras de nutrientes em canais urbanos de macrodrenagem no município de Belém/PA

Abstract

With the expansion and population growth of the municipality of Belém/PA, areas with little or almost no sanitation infrastructure were developed, since as it grew, it circumvented water accidents instead of sanitizing them, resulting in large investments in works of macrodrainage currently, in peripheral areas. This work sought to evaluate the degree of pollution caused by polluting loads of nutrients in the 03 (three) macrodrainage channels, being Quintino Bocaiúva, Timbiras and Caripunas, belonging to BHEN, whose contribution flows into the main source of public supply in the municipality. For this, the work carried out the calculation of polluting loads of nutrients, analyzing NTK, ammoniacal-N, organic-N, Nitrate (NO3) and Total Phosphorus, in 5 qualitative campaigns, in addition to having carried out a bathymetric survey in 3 campaigns, considering the rainy and less rainy period. Initially, the flow results were presented, which after simulation it was verified that the highest flow is related to the Quintino channel, which was to be expected due to its greater contribution area. The correlation between nutrients and physical variables of temperature, OD and pH of the water was also verified. Thus, it was found that despite being small in most cases, there is a correlation between those mentioned. In addition, the concentration of the parameters was analyzed separately, based on the results of the laboratory analysis, in which the forms of nitrogen and phosphorus exceeded the limits recommended in the legislation, also expected due to the high contribution of the subbasins, in addition to there being no treatment efficient domestic sewage system in this area. Finally, the polluting load values were analyzed based on the relationship between flow and concentration, resulting in high values of load released into the receiving body, characterizing a scenario of extreme water degradation. Still, with this relationship it was possible to estimate the population that would be contributing to this scenario, whose numerical values were also quite high and not consistent with the reality in the area. Therefore, through these results, it is possible to affirm that they may be harmful to the waters of the canals, where a significant degradation of the quality of the waters is expected, which will follow to the Guamá river, and consequently, will reach the population that directly or indirectly have contact with these bodies of water