The fractions of metals remediated (%) by varying ratios of com-post and soil mixtures are shown in Fig. 2. A similar trend of metal removal was observed in the two treatments i.e., bioremediation with ‘compost-only’ and ‘compost +plant ’. The remediation ability of the treatment with compost and plant effectively removed greater percentage of metals than the ‘compost-only’ treatment . In ‘compost+plant ’ treatment, higher fractions of Mn (31%), Fe(49%), Cu (51%) and Zn (31%) were removed than in ‘ compost-only ’treatment. An exception is that, Cr showed a higher removal rate(64%) in ‘compost-only’ treated soil than in ‘compost+plant ’ treatment.
Treatments with 1:1 compost/soil mixtures were able to remove the highest fractions of metals while treatments with 1:5 ratios removed the least amount of metals. This may be attributed to high organic matter content present in the 1:1 compost/soil mixtures,which have the highest compost concentration compared to other treatments. Mn was the highest remediated metal followed by Fe and Zn while Cr was the least remediated metal.