Phytoextraction potential of wheat and study on the applicable ratio of converter sludge in some soil-sludge mixtures

Abstract

Converter sludge is a by-product of the “steel industry”, at the wet cleaning process of the converter gas. The sludge might contain heavy metal oxides, more particularly of lead- (Pb) and zinc (Zn) oxides. Our aim is to investigate the accumulation ratio of these components within the different parts of some selected plants during the potential phytoremediation, phytoextraction processes. The investigation was implemented with the collaboration of students, who gained practical knowledge in sample preparation, analysis and data evaluation. The gained knowledge is a good complement to what the students have been learned in higher education and provides useful practical insights into environmental analysis. For the preparation of the laboratory experiment of this research, we made seedling growth tests with white mustard (Sinapis alba) seeds on the 20-40-60-80% mixtures of converter sludge and different kinds of soils. According to the germination results we determined that the most capable mixtures were the converter sludge and the loess mixtures. Wheat (Triticum aestivum) was chosen as a test plant for the experiments. The mixing ratio of the converter sludge was 5-10-15-20-25%. The metal content of the sludge-soil mixtures and the different parts of the wheat plants (shoot, root) were analyzed by XRF instrument. The results showed that the most effective and tolerable ratio of converter sludge can be the 10 and 15% in loamy soil mixtures. Wheat plants seem to be applicable on decreasing of the metal content from the sludge-soil mixtures. The decreasing average ratio was 50 % for Pb, 53 % for Zn, at using the lowest applied ratio into the soils. Further aim is to find other potential industrial plants for decreasing of the ratio toxic elements from the converter sludge.