Biorremediação em efluentes de piscicultura utilizando macrófitas aquáticas Eichhornia crassipes (Pontederiaceae) e probióticos

Abstract

Piscicultural activities in Brazil are growing in fast pace due to their profitability and rapid economic return to producers, besides the fact of being considered the best way to produce first quality protein. However, they generate a considerable amount of effluents that are usually discharged in the environment without any suitable treatment, bringing negative environmental consequences to hydric bodies. Aquatic macrophytes have been used for a long time in treatment of aquaculture effluents, acting as bioremediators to remove compounds of the medium. Recent studies have been reporting the use of probiotics to ameliorate effluents and to reduce organic load in water. The present study is aimed to assess the efficiency of aquatic Eichhornia crassipes macrophytes, associated with probiotics, in bioremediation of effluents produced by pisciculture. Its specific objectives are: 1) to examine physical and chemical variables of effluent from fish tanks treated with Eichhornia crassipes and probiotics, 2) to quantify the green biomass produced by Eichornia crassipes grown in effluents from fish tanks and 3) to propose the development of viable technology in the region for treating pisciculture effluents through bioremediation technique, using Eichhornia crassipes and probiotics. The research was done in the laboratories of the Universidade Federal da Paraíba, Areia/Pb, using fiberglass recipients capable to contain 310 litres of fish tanks effluents, submitted to 3 different treatments: T1 (with Eichhornia crassipes), T2 (with probiotics), T3 (with Eichhornia crassipes and probiotics) and and 1 control recipient (with nor Eichhornia crassipes neither probiotics). The treatments were divided into 3 experimental blocks, and samples for physical and chemical analyses were collected every four days, with a total of twelve days for each block. The delineation was in full randomised blocks. The results of analyses were subjected to variance analysis (ANOVA-one-way) and average values were compared by Tukey's test (p<0,05). The results showed qualitative improvement of physical and chemical properties of the effluents submitted to treatments 1 and 3, presenting significant differences (p<0,05) between the average values of CO 2 , pH and turbidity; BOD diminished in all three treatments but without significant differences. The removal of Total Inorganic Nitrogen in treatments 1, 2, and 3 were of, respectively, 70,9, 54,1 and 73,5 %; the removal of total Phosphorus in treatments 1, 2, and 3 were, respectively, of 85,8, 25,0 and 89,0 %. At the end of the experiment we found in the Eichhornia crassipes submitted to treatments 1 and 3 an increase of humid biomass of, respectively, 132,8 and 134,1%. We observed, also, that through techniques of bioremediation utilizing Eichhornia crassipes it is possible to improve the quality of fish farming effluents and that its association with probiotics does not increase significantly its performance. To great advantage in the use of these vegetables is in their easy handling, quick adaptation and, mainly, in their high primary productivity, being able to temper the load of nutrients thrown in effluents it and decelerate the process of eutrophication of the receiver bodies.