Pós tratamento de efluente de reator anaeróbio via flotação por ar dissolvido e adsorção para remoção de nitrogênio e fósforo de esgoto sanitário

Abstract

The high content of nutrients such as phosphorus and nitrogen in effluents can trigger excessive algal growth (eutrophication). The present study aimed to evaluate the removal of these nutrients with the use in the post-treatment of effluents from anaerobic reactors through dissolved air flotation with the use of zeolite and calcined eggshell as adsorbents. The adsorbents were used separately and together to evaluate the turbidity, phosphorus and nitrogen analyses. Adsorption offers several advantages such as low cost, high efficiency, selectivity and simplicity of operation. Analyzes were performed on a bench scale (Flotest), using aluminum sulfate as a coagulant. They were divided into three stages, the first using zeolite as adsorbent, varying the coagulant dosages by 5, 10 and 15 mg/L, to promote nitrogen removal, showing an average efficiency of 21.4%, reaching a maximum of 31.7 %. The average efficiency in removing phosphate was 68.2% and for decreasing turbidity it was 66.5%. In the second stage, with the study of the calcined eggshell adsorbent, in amounts of 0.5, 1 and 2g/L, the analyzes obtained an average efficiency of 70.2% for phosphate removal, reaching 95% in one treatment. For nitrogen removal of 23.7% and turbidity decrease of 64.4, having samples with increased turbidity compared to raw sewage. And in the third step, the adsorbents together, the average efficiency was 61.1% in phosphorus removal, 21.4% in nitrogen removal. And despite the low removal of turbidity, 15.9%, it was possible to conclude that the use of these adsorbents in flotation was promising.