Seasonal Survey of Bacterial Species and their Bioremediation Potentials in Leachates from a Nigerian Municipal Solid Waste Dumpsite

Abstract

Myriads of microorganisms present in dumpsite leachates produce varieties of extracellular enzymes that can degrade toxic compounds to innocuous products. The present study involved a seasonal survey of bacterial species and their bioremediation potentials in leachate from the Ikueniro open solid waste dumpsite situated in Uhunmwode Local Government Area, Edo State, Nigeria. Bacterial isolation and enumeration of the leachate samples was carried out using pour plate technique. Phenotypic techniques and 16S rRNA gene analysis identified the bacterial isolates. The bacterial mastermix for bioremediation of the leachate consisted of a consortium of bacterial strains isolated from leachate discharging from the Ikhueniro dumpsite. The bioremediation efficiency of the leachate was deduced by measurement of heavy metals and other chemical analytes using standard methods prescribed by the American Public Health Association. The bacterial species isolated from Ikueniro dumpsite such as Bacillus licheniformis strain EGBON & OKORIE 103 and Klebsiella aerogenes strain EGBON & OKORIE 108 were deposited in the United States NCBI GenBank. A consortium of these bacterial strains served as inocula for the bioremediation setup. A huge removal of ammonia from the leachate was observed during the 28-day bioremediation experiment, amounting to a mean bioremediation efficiency of 80.65%. The removal of the heavy metals from the raw leachate by the bacterial mastermix in increasing order was as follows: nickel<copper<zinc<lead<iron<cadmium<arsenic<mercury. Bioremediation of the leachate using indigenous bacteria promises to be an effective tool for management of toxicants from leachates of open solid waste dumpsites.