Ultrafiltration/complexation process for metal removal from pulp and paper industry wastewater

A process for metals removal from totally chlorine free (TCF) wastewater using water-soluble polymeric ligands (WSPL) in combination with ultrafiltration is described. The polymeric ligands addition, contact time between the polymeric ligands and the wastewater, and pH were evaluated. The UF experiments were carried out in dead-end stirred cell and the pressure applied was controlled by nitrogen gas. The membranes used were made from polyvinilidene fluoride (PVDF) by the phase inversion method. Wastewater from “Klabin” Pulp and Paper Industry was used. The performance of water-soluble polymeric ligands poly(vinyl alcohol) (PVA) and polyethyleneimine (PEI) was evaluated by determining metal, color, turbidity and chemical oxygen demand (COD) removal. In general, the complexation/ultrafiltration process was efficient in the removal of those parameters from wastewater, leading to a better effluent quality when compared to ultrafiltration without any ligands addition.

Promising results were obtained for metals removal from TCF (Totally Chlorine Free) bleaching wastewater by coupling complexation with WSPL and ultrafiltration process. This process has increased the wastewater final quality, compared to the single ultrafiltration. The contact time influenced metals removal significantly in both systems, PEI and PVA added wastewater. The obtained permeates from the complexation/ ultrafiltration process were clean having great possibilities of being reused by the industry. The process still has to be optimized in order to reduce contact time between wastewater and WSPL, searching for industrial viability of the process.