Alice Oliveira Aguiar

Laura Hamdan de Andrade; Wadson L. Pires; Luiza B. Grossi; Alice Oliveira Aguiar; Míriam Cristina Santos Amaral

ABSTRACT The aim of this study was to evaluate an innovative treatment route for gold-mining effluents rich in calcium, arsenic, and sulfate. This treatment route comprised two nanofiltration (NF) stages and a two-step intermediate precipitation. Arsenic and iron coprecipitation (first step) and calcium carbonate precipitation (second step) were assessed aiming to treat the first-stage NF concentrate and increase the permeate recovery rate in a second-stage NF. The pH, the molar ratio of Fe/As (first step), and the molar ratio of CO3/Ca (second step) were optimized by using rotational central composite design. Under optimal conditions, the arsenic removal was 99.8% (at pH = 7.0 and Fe/As = 4.0), and the calcium removal was 99.5% (at pH 11.5 and CO3/Ca = 3.5). The supernatant of Ca precipitation had very basic pH and had to be acidified before the second-stage NF. The pH 8.5 proved to be the best one regarding retention efficiency and flux. The flux decay of the second-stage NF was attributed to both osmotic pressure increase and reversible fouling resistance. It was concluded that the proposed treatment system is efficient for the treatment of gold-mining wastewater, ensuring higher production of treated effluent and an easy disposable of the final concentrate.

Laura Hamdan de Andrade; Alice Oliveira Aguiar; Wadson L. Pires; G. A. Miranda; Míriam Cristina Santos Amaral

ABSTRACT This study aimed to evaluate the effect of feed pH (2.2 - original effluent pH – up to 6.0) and temperature (20 up to 40°C) on the performance of integrated ultrafiltration (UF) and nanofiltration (NF) applied to gold mining effluent. pH increase led to a significant decrease in UF permeate flux. NF showed high retention efficiencies of ions when temperature was below 30°C. Retention of high-valence counter-ions to balance the charge of retained co-ions seemed to be the strongest NF mechanisms. Process performance at feed pH of 5.0 was superior in terms of fouling, retention efficiency, and investment cost.

Bárbara C. Ricci; Carolina D. Ferreira; Alice Oliveira Aguiar; Míriam Cristina Santos Amaral

Alice Oliveira Aguiar; Laura Hamdan de Andrade; Bárbara C. Ricci; Wadson L. Pires; Gisele A. Miranda; Míriam Cristina Santos Amaral

Laura Hamdan de Andrade; Bárbara C. Ricci; Luiza B. Grossi; Wadson L. Pires; Alice Oliveira Aguiar; Míriam Cristina Santos Amaral

Laura Hamdan de Andrade; Alice Oliveira Aguiar; Wadson L. Pires; Luiza B. Grossi; Míriam Cristina Santos Amaral

Laura Hamdan de Andrade; Alice Oliveira Aguiar; Wadson L. Pires; G. A. Miranda; L. P. T. Teixeira; G. C. C. Almeida; Míriam Cristina Santos Amaral

Alice Oliveira Aguiar; Laura Hamdan de Andrade; Luiza B. Grossi; Wadson L. Pires; Míriam Cristina Santos Amaral

Laura Hamdan de Andrade; Alice Oliveira Aguiar; Wadson L. Pires; Míriam Santos Amaral

Alice Oliveira Aguiar; Aline Barros Felix De Sousa; Bárbara C. Ricci; Lorena Nunes Dias; Mariana Da Mata Sacramento