Principais impactos nas margens do Baixo Rio Bodocongó - PB, decorrentes da irrigação com águas poluídas com esgoto

Abstract

The lower basin of Bodocongó River is located in the Southwest region of the State of Paraíba and is part of watershed of Paraíba River. The river receives several diffuse sewage contributions and the final effluent of the Wastewater Treatment Plant (WTP) of Campina Grande city. The distance between the WTP and the river end, here called as Lower Bodocongó, has about 50 km of extension and its water is used for unrestricted irrigation of forage and vegetables (lettuce, cabbage, tomatoes), and for recreation (primary contact) purposes among others. In the present study an evaluation is made of the physical, chemical and sanitary parameters of water and the impacts of its use on the sanitary quality of the irrigated crops (elephant grass and cabbage) and soil salinization. The water of the Lower Bodocongó was found to be inappropriate for unrestricted irrigation. At none of the points sampled, water conformed simultaneously to two standards recommended by WHO for unrestricted irrigation: fecal coliforms < 1000 CFU 100 mL-1 and helmints eggs < 1egg L-1. The cabbage irrigated with water presented a concentration of 1000 MPN g-1, 17 times higher than the maximum allowed by the Brazilian legislation for the raw consumption. These waters present electrical conductivity varying from 2.42 to 3.51 dS m-1 and salt content irrigated soils was higher than that of adjacent non-irrigated soils.