Heavy metals removal in dual media filters

Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente – Perfil de Engenharia Sanitária

The purpose of this study was to investigate physicochemical mechanisms for the removal of heavy metals from the effluent of Harnaschpolder’s WWTP Pilot Installation in the South of Netherlands. This effluent is partially submitted to tertiary treatment in a water reuse pilot which aims the production of water for two different end‑uses: crop irrigation in greenhouses and surface‑type water. Tertiary filters were mounted and started up at the reuse pilot and specific concentrations of heavy metals were dosed in the filters. Removal efficiencies were then calculated after the end of the experiments. As a parallel research project, the removal of HM was also carried out by inoculating selected bacteria (biosorption). Solubility curves were calculated for the dosed heavy metals (Cd, Cu, Ni, Zn) using PHREEQc programme, to predict if heavy metal precipitation occurred in the filters (using the same experimental data: temperature, pH , alkalinity, etc.). Results show that physicochemical precipitation was not the primary removal mechanism for heavy metals. The results suggest that other mechanisms such as adsorption and/or chelation may be involved in the removal of these species.