Efeito da aplicação de lixiviado tratado de aterro sanitário urbano nas características vegetativas do capim elefante (Pennisetum purpureum Schum)

Abstract

The fate given to solid urban waste generated by modern society is one of the major environmental concerns of today. Its inadequate disposal is directly related to contamination of soil, water and air. Landfill is the final disposal of solid urban waste with greater social and economic benefits and lower risks of environmental degradation. Urban waste presents a very complex mixture of materials of diverse nature. The liquid by-product, generated from the decomposition of the grounded material together with the rainwater entering the system through surface drainage and percolating into the compacted layers of waste, is called landfill leachate. When properly treated, this effluent can be reused for other activities such as the production of biomass for the vegetation cover of landfills. The present study aimed to evaluate the changes in the physical and chemical quality of the treated effluent from percolated urban solid waste aiming the agricultural reuse through its application in elephant grass and to quantify the vegetative characteristics of the elephant grass under different applications of the treated effluent. The study was developed in an experimental area of 55 m2 installed in a landfill located in the Metropolitan Region of Recife. At the site, 28 experimental units were delimited, seven treatments repeated four times in a randomized complete block design. Each experimental unit had a 1.0 m × 1.0 m (1.0 m2) and 0.30 m plot size, in which elephant grass (Pennisetum purpureum Schum.) was grown in soil classified as typical Eutrophic Yellow Argissolo. The following treatments were used: T1 - supply water (SW); T2 -1 L percolated effluent; T3 - 2 L percolated effluent; T4 - 3 L percolated effluent; T5 - 4 L percolating effluent; T6 - 5 L percolating effluent; and T7 - 6 L percolating effluent. Concomitantly with the experimental period, the physical-chemical characteristics of the soil, the physical-chemical and microbiological characteristics of the percolate and the water supply and the vegetative characteristics of the elephant grass were analyzed. The results showed that the treated effluent from percolated urban solid waste satisfactorily met the analyzed water quality parameters for irrigation. High concentrations of this effluent presented better performance in relation to the growth parameter (plant height) of the elephant grass and also the dry matter production of the leaves.