Utilization of waste humate product (iron humate) for the phosphorus removal from waters

Iron humate (IH) produced as a waste by-product during an industrial manufacture of humic substances from young brown coals was tested as a new cost-effective sorbent for the removal of inorganic phosphorus from waters. The sorption capacity approaching ca. 10 mg P g(-1) was comparable with that reported for other non-conventional sorbents, and was nearly independent on pH in a slightly acidic to neutral working range of the sorbent. It was found that the phosphate binding to IH is a relatively slow process requiring several days to attain equilibrium. The kinetics of the phosphate sorption was described by a recently introduced modified pseudo-n-order (MPnO) rate equation. Extraction tests showed that a major part of phosphorus in IH is associated strongly with iron-containing compounds or humate matrix of the sorbent and may be hardly liberated into the environment. Only minor fraction of phosphorus is readily mobilizable by leaching with water. (C) 2010 Elsevier B.V. All rights reserved.