Aspectos geotécnicos e ambientais para a disposição adequada de lodo de esgoto

Abstract

Despite the fact that sewage systems are highly efficient in removing organic matter, pathogens and nutrients, sewage treatment plants have experienced challenges related to the management of the generation of solid waste. The major concern with the generated sewage sludge (biosolids) is that it presents in its composition elements that on contact with the ground and groundwater may compromise their quality, contaminating them. In this context, there have been studies aimed at verifying the potential contamination of sewage sludge, as well as studies on the mechanical behaviour of the soil under the action of this disposal process. The objective of this research was to investigate the transport of sewage sludge contaminants in nature state, and the monospecies transport of nickel and chromium solutions and further to verify how the sludge constituents can change the soil strength characteristics. This survey conducted geotechnical soil characterization tests, geo-environmental tests (diffusion and sorption) in the laboratory, and diffusion in the field, and also soil strength tests (consolidation and direct shear and simple compression). Results indicate that the soil under consideration is a typical laterite soil from the DF, and its coefficient of permeability allows the soil to be used as a compacted liner. Contaminant transport results showed that the contaminant in nature state suffers from dispersion, due to the intense biological activity and increased capacity of the soil cation exchange. However, results of the synthetic monospecies solutions indicate the tendency for this type of test, the concentration decreases as a function of time. The strength results demonstrated that the sewage sludge contaminants have characteristics that may change the cementation connections. The results in simulating successive applications of sewage sludge on the soil (five applications), were the ones the showed lower cohesion values and higher strains in the consolidation curve. On the other hand, the soil contaminated with sewage sludge and lime, was the one that showed the lowest cohesion values. Thus, it can be seen that the constituents of the sewage sludge, can migrate to the soil contaminating it, and that its constituents may decrease its strength.

Effectiveness of Polyvinylidene Fluoride Fibers (PVDF) in the Diffusion and Adsorption Processes of Atrazine in a Sandy Soil

“…The fiber absorption test has no specific existing standard, so the test performed in this research followed the procedure of two absorption tests in the literature [20,21], based on the [21] that portrays the determination of water absorption by immersion in concrete.…”