Characteristics and Distribution of Metallic Elements in Landfill Leachates

Abstract

In this study we have examined the leachates from a small sanitary landfill paying attention to the characterization of the colloids in the leachates by their size and the distribution of the metallic elements associated to the colloids in the leachates. The following points are noticed: iron is the most abundant metallic element in the leachate. Its concentration is found to be from 0.4 to 4.0 mg l−1. Other metallic elements such as Cr, Ni, Mn, Cu, Co, Al and Zn exist as trace amounts (from 0.1 to 1.0 mg l−1). Heavy metals such as Pb and Cd barely exist as a dissolved form. Total solids (TS) content in the raw leachates is around 14.9 g l−1. About 90 % of the TS are due to the solutes of which size is less than 1.2 nm. Fixed solids (FS) content is around 8.99 g l−1 being about 60% of the total solids. The relative distribution of the solutes becomes more important as the molecular size diminishes. Most of the alkaline and alkaline-earth metal ions were found in the filtrate collected through filter papers where molecular cut-off size is less than 500. Most of the iron ions are associated with the colloids of larger size than the alkaline or alkaline-earth metals ions. The major part of the solids in leachates is composed of mineral materials. It seems that most of the Cr exists in association with the colloids of 0.45–2.8 µm in size.