Removal and recovery of heavy metals by bacteria isolated from activated sludge treating industrial effluents and municipal wastewater

Abstract

A total of nineteen metal-resistant and non-resistant bacteria from activated sludge treating both metal-contaminated industrial effluents and municipal wastewater were isolated and identified. These included both Gram-positive (e.g. Micrococcus) and Gram-negative (e.g. Pseudomonas) bacteria. The biosorption capacity of these strains for five different heavy metals (copper, nickel, zinc, lead and chromium) was determined at pH 5 and initial metal concentration 100 mg/L. Pseudomonas pseudoalcaligenes and Micrococcus luteus were found to be capable of removing significant amounts of copper and lead. Hence, they were selected for further investigations. Langmuir adsorption isotherms adequately represented the distribution of copper and lead for both species. The study of pH effect on metal removal for both species indicated that the metal biosorption increased with increasing pH from 2 to 6. The effect of competing cations on biosorption of P. pseudoalcaligenes was studied. Sulphuric acid (0.05 M) was the most efficient desorption medium among the eleven reagents tested. Over 90% of copper sorbed on the cells of M. luteus could be recovered by washing with 0.05 M sulphuric acid within five minutes. The biosorbent was used for at least five biosorption and desorption cycles without loss of copper removal capacity. Immobilization of M. luteus in 2% calcium alginate and 10% polyacrylamide gel beads increased copper uptake by 61%.

Isolation and characterization of heavy metal tolerant Gram-positive bacteria with bioremedial properties from municipal waste rich soil of Kestopur canal (Kolkata), West Bengal, India

“…Low removal of nickel at lower pH range by Pencillium chrysogenum has also been reported (Tian-Wei et al 2004). Removal of copper and lead (Leung et al 2000) and chromium and nickel (Congeevaram et al 2007) by Micrococcus luteus also followed the same trend. Very few bacterial species are known to remove metals at pH above 8.…”

Bioremediation of Chromium from Fortified Solutions by Phanerochaete Chrysosporium (MTCC 787)

“…Low removal of nickel at lower pH range by Pencillium chrysogenum has also been reported [46]. Removal of copper and lead by Micrococcus luteus [47] also showed the same trend. And the reason behind this results is that the percentage removal of chromium at high pH is depends upon the negative charge present on the fungal surface [48] due to the functional groups which helpful in the binding of cation Cr (VI) up to the optimum range of pH while at lower pH, due to the protonation of binding site resulting from high concentration of proton, negative charge intensity on the site is reduced which results in the reduction or inhibition for the binding of metal ion.…”

Nickel biosorption by Acinetobacter baumannii and Pseudomonas aeruginosa isolated from industrial wastewater

“…In similar studies with other metal cations, Malekzadeh et al (11) isolated a strain of Pseudomonas sp. highly capable of accumulating uranium at pH 6.5; also, Leung et al (10) found that lead and copper uptake by P. pseudoalcaligenes and Micrococcus luteus increases as pH values raise from 2 to 6.…”