Eggshell: A green adsorbent for heavy metal removal in an MBR system

• Membrane necessity of the secondary settler from water treatment line.
• Effluent Clarification by MBR can be reach 100% of efficiency.
• The process shows a good flexibility to influent load change.
• Complete solid removal and to a strong reduction of the pathogenic load.
• Application of Eggshell and MBR has been investigated with new approach.

Presence of heavy metals as well as different metal ions in treated wastewater is a problem for the environment as well as human health. This paper aims to investigate the possibility to combine an MBR (membrane biological reactor) with an adsorption process onto powdered eggshell and eggshell membrane in order to improve metal removal from wastewater. The first step of the experimental analysis consists of the evaluation of the compatibility between the two processes. Then, a study about sorbent concentration and size effect on fouling was conducted, because the use of this kind of sorbent could affect membrane performance. The second step of the work concerns the check up of eggshell removal capacity as a function of sorbent size, achieved treating an aqueous solution containing Al3+, Fe2+ and Zn2+ as water pollutants. Finally, synthetic wastewater, containing the metal species, was treated by two alternative process schemes: one of them performs the metal uptake in a dedicated adsorption unit, before the MBR. In the second, the two processes take place in the same unit. Results demonstrate that the optimization of the first option could be a solution to MBR upgrading.