Resíduo do lodo da estação de tratamento de água da Região Metropolitana de Belém em substituição parcial ao cimento Portland em argamassa

Abstract

As a result of the growth of cities and the greater demand for quality of life, the demand for drinking water has increased in recent decades. Like any industrial process, the production of water for human use generates large quantities of by-products, being the main designated residue of waste, sludge or sludge of Water Treatment Station (WTPS). So far, the most common destination for the WTPS is the watercourse, although it is considered a solid waste. These factors motivate research aimed at alleviating the problems caused by incorrect waste disposal in the environment. In this sense, the present paper presents an alternative proposal for the disposal of WTPS in mortar, partially replacing cement, whose extraction and employment also cause environmental impact. The WTPS was used in the mortar with the least possible alteration of the residue, that is, its in natura use to avoid energy expenditure and to enable its use. The characterization of the materials used, as well as the physical, chemical, mineralogical and thermal characterization of the sludge extracted from WTP Bolonha, located in the metropolitan area of Belém, was carried out. The analyzes provided data that were the basis for investigations of viable applications for the residue. The first investigation studied its use as pozzolan in Portland cement, for which the tests that analyzed its potential reactivity with lime and cement were carried out. The investigation of the pozzolanic activity, both with lime and cement CP II-F-32, showed that mortars with replacement contents obtained lower results than required by the respective standards, discarding their use for this purpose. The second research analyzed the effects of the use of the residue as a filler in Portland cement, the reference mortar (without addition of sludge) and traces with additions of 6, 8 and 10% were used. In the compressive strength the 6% replacement content of the cement Portland CP I-25 by WTPS produced a resistance increase of 8,93% at 7 days and 3,24% at 28 days of age, in relation to the reference mortar, besides absorbing 7,81% water less than conventional mortar. Although the use of sludge occurs in small quantities, its use is feasible, since its incorporation will reduce the consumption of the raw material required for the production of mortar.