Micro and vermicompost assisted remediation of heavy metal contaminated soils using phytoextractors

Heavy metals (HMs) contamination is a serious environmental concern in different parts of the world. In this study, two indigenous phytoextractors, Sida acuta and Melissa officinalis L. were used and assisted with plant growth promoting bacteria (PGPB) and vermicompost by-product (vermicast) produced for remediation purposes. The concentration of heavy metal accumulation in plants were determined using atomic absorption spectrophotometry and analyzed by canonical discriminant analysis (CDA). Pre- and post-remediation analysis of the physico-chemical properties of the soil was conducted. M. officinalis L components in the primary location were able to remove HMs, particularly lead (Pb) and cadmium (Cd) with metalloid (arsenic (As) concentration in plant ranges from 0.09 to 4.39 ppm, 0.07–10.35 ppm and 0.007–0.33 ppm, correspondingly. In the contaminated soil after remediation, the amount of Pb varied from 5.88 to 12.37 ppm, Cd concentration was between (0.026–0.58 ppm) while As was between 0.32 and 5.48 ppm. HMs concentration of soil remediated with Sida acuta had Pb, Cd, As varied from (1.68–10.7 ppm), (0.002–0.43 ppm) and As (0.27–3.79 ppm) individually. The organic carbon and nitrogen concentration before (C: 0.27; N: 0.01) and after (C:6.40; N: 0.70) the remediation process showed a significant increase, pointing to less contaminated soil. The role of vermitechnology in phytoremediation is important and could be employed to restore a contaminated soil with HMs as reported in this study.