Otimização preliminar da adsorção de nitrato em mananciais subterrâneos do município de Pedra Branca/CE

Abstract

Problems related to the quality of surface water sources, and their scarcity, have strongly favored the use of underground water sources as a supply source for diverse uses. In this context, even though they are considered more protected than surface water, groundwater can also be polluted or contaminated. Among the various pollutants responsible for the contamination of underground sources, nitrate is the most frequent and has received increasing attention in recent years through the investigation of new technologies for its removal. In this work, Powdered Activated Carbon (PAC) of plant origin was tested for removal by adsorption of nitrate from groundwater. The water used in the experiments was collected in the municipality of Pedra Branca - CE. The Central Composite Design (CCD) was applied, combined with the analysis of contour curves and response surfaces in the study of the variables adsorbent dosage (Powdered Activated Carbon) and contact time, in order to maximize the responses nitrate removal and conductivity removal. The highest nitrate removals (above 2%) were found between 0.04 and 2.00 g/L for the dosage and involving the entire range studied of contact time, that is, from 5 to 122.16 minutes. For conductivity removal, it is observed that the best performance (above 10%) was found between 60 and 122.16 minutes and a dosage between 0.04 and 2.50 g/L. Based on the experiments carried out and analysis of variance (ANOVA), the models were classified as statistically significant. However, no experimental validation was found, and interference in the adsorption process may have occurred. The modeling and optimization by factorial design associated with the response surface methodology can generate statistically valid models, but due to the low removal efficiencies, it is recommended to carry out further investigations in order to bring improvements to the optimization process.