Planejamento experimental e modelagem estatística do efeito do uso do lodo de esgoto em solos

Abstract

Optimized mathematical models relative to the effects of the use of sewage sludge in the cultivation in the soils, Brazil, will be elaborated and validated here. The releasing of pollutants in the environment has been under severe control in developed countries, and there has been given greater importance to the matter in developing ones, such as Brazil. The greatest volume of it comes from domestic waste and from the wastewater treatment. Sewage sludge (SS) is a general denomination to the solid waste generated by the wastewater treatment system. The SS may present in its composition undesirable, from the environmental point of view, biological and chemical elements, that is, it may contain elements that may cause several diseases and contaminations in contact with men or with the fauna and the flora. Thus, any decision about the most appropriate final destination of the SS depends on the evaluation and the minimization of contamination risks to men and to the environment. There are plenty of these elements, and they may be classified in two groups: chemical contaminants and biological contaminants (many of them are pathogen organisms, which cause human diseases). Among the pollutants of the SS, the chemical contaminants (heavy metals) constitute the greatest group and must be constantly monitored because of the risks of contamination to men, animals and plants. Among the several existing alternatives to the disposition of the SS, it seems that the most convenient and one of the most promising, mainly from the economic point of view, is the agricultural utilization, not only because of its potential as conditioner and fertilizer of soils, but also because of the fact that the soils have, in general, a high power of clearance. In this work, it will be presented strategies to the definition of adequate conditions of experiments by means of planning techniques and of experimental optimization. From this methodology, it is hopeful to get the definition of working optimized conditions in a way that it may be obtained models of simulation to the effects of the sewage sludge in the cultivation of spices in the soils