Bioavailability and leachability of heavy metals during water hyacinth composting

Abstract

The bioavailability and leachability of heavy metals is important role when considering their toxicity during composting following land application. Therefore, studies were carried out on Zn, Cu, Mn, Fe, Ni, Pb, Cd and Cr during 30 days agitated-pile composting of water hyacinth (Eichhornia crassipes). This study investigated the influence of parameters such as pH, temperature and organic matter content on the distribution of heavy metal bioavailability and leachability during composting of water hyacinth. Results showed that the contents of total metal concentration increased during the composting process. The bioavailability of heavy metals was investigated in the form of water soluble and diethylene triamine pentaacetic acid (DTPA) extractable. In the water soluble, DTPA and leachable Zn, Cu, Mn, Ni and Cr reduced but there was a gradual increase in the Fe concentration during the composting process. Furthermore, in water soluble and leachable Ni, Cd and Pb were not detected and in DTPA extractable Cd and Pb were also not detected during 30 days of composting.