Aplica??o de água residuária de processamento de mandioca em sistema de irriga??o por gotejamento

摘要

The wastewater discarded from the cassava processing causes a serious environmental problem when dumped into water bodies. On the other hand, this residue can be used as a source of nutrients for crops. However, it is necessary to control the quality of this effluent because of the negative effects that it may cause to the irrigation system. This study aimed to evaluate a drip irrigation system with the application of cassava wastewater by determining the coefficients of variation of emitter discharge (CVq), distribution uniformity (DUC) and Christiansen’s uniformity (CUC). The experiment was conducted at C. Vale cassava processing factory in the city of Terra Roxa (Paraná, Brazil). Four systems of 66 m2 were installed, with 7 lateral lines of 11 m, spaced in 1 m, with one dripper at each 0.30 m. The systems were fed by two tanks of 1000 L, situated at 1.5 m and 2.0 m above the ground and containing water for irrigation and the cassava wastewater for fertigation. A plastic mesh filter was installed in the tank and two digital manometers controlled the pressure. Thirty trials were performed for each treatment, using the methodologies of Keller and Karmeli (1975) and Denículi (1980). Excellent averages, above 90%, were obtained for both DUC and CUC. The results showed no expressive differences between the use of water and the use of effluent, demonstrating that cassava wastewater can be applied efficiently on a drip irrigation system.