Seasonal performance of aquatic macrophytes in improving physicochemical parameters of swine wastewater

Desempenho sazonal de macrófitas aquáticas na melhoria de parâmetros físico-químicos de efluente de suinocultura

Abstract

Swine wastewaters (SW) present organic load and nutrient content, what have caused degradation of water quality in many watercourses. Thus, the aquatic macrophytes represent an alternative for the depollution of these wastewaters, due to the high recovery power. The aim of this study was to evaluate the performance of the Eichhornia crassipes (Mart.) Solms, Pistia stratiotes L. and Salvinia auriculata Aubl. in improving the physicochemical targets of SW, as well as to quantify the total ammoniacal nitrogen (NH₄⁺) and total phosphorus (total P) in the plant tissue of the macrophytes and the dry matter biomass (DMB) in two seasons of the year (spring and winter). The experiment was designed in a randomized block design, with 4 treatments (T) with 4 replicates: T1 = Control (without plants); T2 = E. crassipes; T3 = P. stratiotes; and T4 = S. auriculata, submitted to a SW diluted in 50% water. The monitoring is done in tanks during a period of 30 days of each season. Electrical conductivity (EC), dissolved oxygen (DO), turbidity, NH₄⁺ and dissolved phosphorus (P) were analyzed in the SW. In the plants, the contents of NH₄⁺, total P and DMB were determined. It was verified that, in the spring, the plants showed higher production of DMB and a more significant reduction of EC, NH₄⁺ and P, when compared to the plants managed in the SW in the winter. E. crassipes was more efficient at removing P (39%) and total NH₄⁺ (80.2%), and EC reducing (92%) of SW and DMB production in the spring. The results demonstrated that the NH₄⁺ uptake by E. crassipes contributed to a considerable removal of NH₄⁺ and P from SW.

Keywords:
pollution; physicochemical parameters; Eichhornia crassipes (Mart.) Solms; Pistia stratiotes L.; Salvinia auriculata Aubl