Trace metal accumulation and phytoremediation potential of four crop plants cultivated on pure sewage sludge

Phytoremediation is a viable strategy to remove trace metal contaminants from sewage sludge but still is poorly investigated. The aim of this study was to quantify the trace metal removal of B. napus, B. juncea, H. annuus, Z. mays grown on pure sewage sludge. Each species was grown on six different sewage sludge for 8 weeks and sludge were analysed for trace metal content and physico-chemical characteristics. Our results confirmed that all the tested sludge supported plant growth. The tested sludge showed a plant vigorousness lower (46% of sludge) or similar/increased (54% of sludge) compared to control treatment. B. juncea and B. napus were the most efficient species in the bioaccumulation, of trace metals. The average percentage of metals removed by the selected species was 0.2% for As, 0.85% for Cd, 0.09% for Cr, 0.36% for Cu, 0.36% for Ni, 4.2% for Se, 1.2% for Zn. In conclusion, our results showed that phytoremediation can be applied to sewage sludge, despite the chosen species have low efficiency in trace element removal. Further studies using hyperaccumulator species are needed which may lead to a higher efficiency of the process opening up new possibilities for the management strategies of this waste.