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.