Viabilidade do uso de águas superficiais poluídas tratadas através de sistemas de wetlands construídos no cultivo do feijão.

Abstract

This research aimed to study the technical and environmental feasibility of the use of polluted water treated through the wetlands system built in bean cultivation with pressurized irrigation. The experiment was conducted in a greenhouse at the Federal University of Campina Grande - PB. The experimental phase was to characterize the treated effluent by two wetlands systems built, one being preceded by a UASB system and make the reuse of treated effluent for irrigation of bean crop (Phaseolos vulgaris L.), which was grown under three systems of pressurized irrigation: surface drip, subsurface and micro sprinkler. The design consisted of randomized blocks in range, resulting in nine treatments with 4 repetitions, totaling 36 installments. From the results it can be seen that in general, the irrigation system for the treated effluent and the UASB + wetland were responsible for the better growth of the bean at the end of its cycle. The interaction between factors types of water and irrigation systems had no effect on any of the production and biomass components; however, as an isolated effect of each factor, it was found that the type of water affect dry weight of 100 grains, dry mass of petiole stem and dry weight of shoots, since the irrigation system affected the number of string beans per plant, dry weight of 100 grains and the ratio of dry weight of shoot and total dry mass. For mass components of 100 grains and dry mass of petiole stem the micro sprinkler system showed superior efficiency to the other with the use of water from the treatment UASB + wetland, as the highest values for the number of pods per plant and the ratio of dry weight of shoot and total dry weight were obtained under subsurface drip system. The flow of emitters used in the experiment was not affected by the type of water used, regardless of the type of irrigation system. Regarding the physical and chemical characteristics can be concluded that the pH of the water treated by the wetland and wetland UASB + did not affect plant development. The treated effluent used in bean crop irrigation showed no restrictions on electrical conductivity, sodium, calcium and magnesium, presenting low probability of sodification, getting a C2S1 water type classification. The treated effluent by wetland system and the UASB + wetland showed microbiological characteristics recommended for irrigation of tree, cereal and forage crops. Referring to parasitological parameters, no parasitic shape (egg helminthes and protozoan cyst) was found in the treated effluent, which means that the treatment systems used in the experiment are effective in removing these parasites found in raw wastewater samples. No grain sample irrigated beans with 9 treatments showed contamination by Escherichia coli and thermo tolerant coli forms above 100NMP / g, introducing suitable for consumption. Microbiological evaluations of soil used in the experiment, carried out after the end of the cycle, showed no contamination by the E. Coli. From the results presented in this research, it is concluded that the use of polluted water seeping in Bodocongó Stream in Campina Grande, PB offers great risk of environmental contamination and should not be used without proper treatment, in the cultivation of crops agricultural.