Enzymatically mediated bioprecipitation of heavy metals from industrial wastes and single ion solutions by mammalian alkaline phosphatase

Abstract

The study was aimed at investigating the potential use of calf intestinal alkaline phosphatase (CIAP) enzyme in the removal of heavy metals (Cd(2+), Ni(2+), Co(2+) and Cr(3+/6+)) from single ion solutions as well as tannery and electroplating effluents. CIAP mediated bioremediation (white biotechnology) is a novel technique that is eco-friendly and cost effective unlike the conventional chemical technologies. Typical reactions containing the enzyme (CIAP) and p-nitrophenyl phosphate (pNPP) as substrate in Tris-HCl buffer (pH 8 and 11) and either single ion metal solutions (250 ppm and 1000 ppm) or effluents from tannery or electroplating industry were incubated at 37°C for 30 min, 60 min and 120 min. The inorganic phosphate (P(i)) generated due to catalytic breakdown of pNPP complexes free metal ions as metal-phosphate and the amount of metal precipitated was derived by estimating the reduction in the free metal ion present in the supernatant of reactions employing atomic absorption spectrophotometer (AAS). Better precipitation of metal was obtained at pH 11 than at pH 8 and between the two concentrations of different metals tested, an initial metal concentration of 250 ppm in the reaction gave more precipitation than with 1000 ppm. Experimental data showed that at pH 11, the percentage of removal of metal ions (for an initial concentration of 250 ppm) was in the following order: Cd(2+) (80.99%) > Ni(2+) (64.78%) > Cr(3+) > (46.15%) > Co(2+) (36.47%) > Cr(6+) (32.33%). The overall removal of Cr(3+) and Cr(6+) from tannery effluent was 32.77% and 37.39% respectively in 120 min at pH 11. Likewise, the overall removal of Cd(2+), Co(2+) and Ni(2+) from electroplating effluent was 50.42%, 13.93% and 38.64% respectively in 120 min at pH 11. The study demonstrates that bioprecipitation by CIAP may be a viable and environmental friendly method for clean-up of heavy metals from tannery and electroplating effluents.

Enzymatic bioleaching of metals from printed circuit board

“…Enzymatic bio-Fenton process Enzymatic bioleaching of metals required less time and metal recovery efficiency was also higher. Application of enzymes for bioremediation is an emerging technology (Chaudhuri et al 2013). There are several benefits of using enzymes for environmental applications.…”

“…Enzymes are readily absorbed back into nature. They do not create disposal problems in bioremediation processes as in biomass produced using living cells (Alcalde et al 2006;Chaudhuri et al 2013). A use of microorganism for bioremediation has many limitations.…”

“…A series of enzyme-catalyzed reactions are involved in bioremediation process. Therefore, most of the above-mentioned adverse factors can be eliminated with a use of enzyme (Ahuja et al 2004;Sutherland et al 2004;Alcalde et al 2006;Chaudhuri et al 2013). Use of enzymes for bioleaching of metals will help to develop novel processes with better affinity, capacity, and selectivity.…”

Isolation and characterization of organophosphorus phosphatases from Bacillus thuringiensis MB497 capable of degrading Chlorpyrifos, Triazophos and Dimethoate

“…Bacterial cell pellets were resuspended in 1 ml of phosphate buffer with pH 7 and cells were disrupted using silica/glass beads. The lysate was centrifuged at 30,000 g at 4 C for 30 min to remove all cell debris and the supernatant was used as enzyme source for intracellular OPP activity [22]. The 3 ml of this supernatant enzyme extract was mixed with substrate buffer mixture (1 ml) after various time intervals and incubated for 30 min.…”

Application of alkaline phosphatase for heavy metals precipitation using ascorbic acid 2-phosphate as an effective natural substrate

“…The pH of the tannery and electroplating effluents was found to be 9 and 10, respectively. Acid digestion of the effluents was performed using a mixture of nitric acid and perchloric acid (5:1) as described before (Chaudhuri et al 2013b), and the quantification of the metals was done using atomic absorption spectrophotometer (AAS).…”