Isaac Volschan

Study of the recovery of phosphorus from struvite precipitation in supernatant line from anaerobic digesters of sludge

The goal of this work was to study the effective recovery of phosphorus from the supernatant of anaerobic digestion of sewage sludge by precipitation as struvite. The formation of struvite is envisioned as a promising process for nutrient removal and subsequent recovery, thus providing a strong incentive for its implementation, since the sewage is a renewable source of phosphorus. Struvite precipitation was obtained by controlled addition of Mg(OH)2 or MgCl2. We evaluated the removal of ammonia and phosphate under equimolar conditions of magnesium and magnesium stoichiometric excess of 100 to 200% relative to the limiting reagent, under a stirring speed of 300 rpm at pH 8, 9 and 10. The best condition was MgCl2 in 1:1 molar ratio to phosphate, considering the stoichiometric ratio [PO4(3-)]:[NH4(+)] of 0.13 (presented by raw sample). The results show the best cost-benefit ratio, removal of phosphate of 90.6% and ammonium removal of 29%, resulting in 23 mg l(-1) PO4(3-) and 265 mg l(-1) NH4(+) concentration in effluent.

A evolução do processo de avaliação e gerenciamento de material relacionado às atividades de dragagem no Brasil: Uma análise comparativa entre as Resoluções CONAMA n° 344/04 e n° 454/12

In 2004, the National Council for the Environment (Conselho Nacional do Meio Ambiente - CONAMA) approved the first Brazilian regulation on procedures for evaluation of dredged material: CONAMA Resolution No. 344/04. This normative act established that, within five years from the date of its publication, there would be a revision of the national guideline values that ​were established for the classification of dredged material. This review took place, culminating in the publication of CONAMA Resolution No. 454/12. This article presents a comparative analysis between the CONAMA Resolution No. 344/04 and CONAMA Resolution No. 454/12, in order to check the main changes and additions that were made. We conclude that the CONAMA Resolution No. 454/12 not only refined the national guideline values ​​for the classification of dredged material, but also regulated relevant aspects related to the environmental licensing of dredging activities and to the management and disposal of dredged material.