Biosorption of Pb by Chlorella vulgaris (Chlorophyceae) at laboratory scale

REGALDO, L.; GAGNETEN, A.M.; GERVASIO, S.; RENO, U.; TROIANI, H.

Bertlín

Congreso; 6th SETAC world Congress ? SETAC Europe 22nd Annual Meeting.; 2012

SETAC WORLD - SETAC EUROPE

In the lower Salado River (Santa Fe Province, Argentina) were reported levels of Cu, Cr and Pb in water, higher than permitted standards, thus highlighting the urgency of implementing remedial measures. Among the conventional methods to capture metal ions from aqueous solutions are ineffective when the volume of wastewater is high and the concentration of metal ions to be removed is low (1-100 mgL-1). An alternative is biosorption technology, using materials of biological origin. In the present study we analyze the efficiency of Chlorella vulgaris (Chlorophyceae) to remove Pb at laboratory scale.The microalgae were harvested in exponential growth phase, centrifuged and resuspended twice in ultrapure sterile distilled water. After measure of algae concentration, we used three real concentrations of Pb+2 (Pb (NO3)2: 1.951 [C1], 2.826 [C2] and 4.830 [C3] mgL-1 with their respective controls, all in triplicate (50 mL-1). The vessels were maintained in an incubation chamber under controlled temperature (23±1°C), continuous illumination (3000 lux) and daily shaking. At 10 and 30 min, 1, 12 and 24 h of exposure, they were centrifuged for 10 min at 3000 rpm, separating the supernatant from the pellet of algae. Both matrices were analyzed by atomic absorption spectrophotometry. For each time and concentration, we calculated the % of removal, the concentration factor (CF= [metal algae] / [metal water]). Pearson correlations were performed to relate the concentration of Pb accumulated by C. vulgaris and the remaining in the supernatant.C. vulgaris removed 50% and 47% of Pb at 10 min of exposure; 100% and 87% at 1 h exposure in C1 and C2 respectively. The maximum percentage (72 %) was obtained at 12 and 24 h in C3. After 12 h, we observed desorption of Pb, with concentrations ranging from 2.62 mgL-1 to 2.58 between 12 h and 24 h in C2. In C3, 3.27 mgL-1 (12 h) and 3.01 mgL-1 (24 h). The CF in C1 was >1 at 1 h of exposition, in C2 at 12 h was 0.93, falling slightly at 24 h. In C3 the CF was