A Robust High-Pressure RO Technology to Overcome the Barriers to Full Circularity in Cr(III) Electroplating Operations

Electroplating is a widely used technology for anticorrosion
materials
and decorative coatings. In view of the transition to a circular economy,
the current electroplating wastewater treatment disposing of heavy
metal sludge and wastewater severely lacks sustainability. Authors
recently reported the successful recycling of electroplating agents
using hybrid semibatch/batch reverse osmosis technology (hybrid RO).
Despite promising results, technology assessment to treat new, second-generation
electrolytes, enhance boric acid recovery, close the water loops,
and evaluate process robustness is still needed. This study investigates
the viability of a high-pressure (120 bar) hybrid RO system, working
with the DuPont XUS180808 membrane, to reclaim valuable second-generation
plating components and water from electroplating rinses. The pilot-scale
system showcased resilience in processing artificial electroplating
wastewaters of variable concentration, achieving water recoveries
of ≤87.7%, increasing chromium and sulfate to electrolyte levels
(>6 g/L and >80 g/L), with low energy consumptions (≤2.7
kWh/m3), underlining its potential as a circular treatment
in the
chromium electroplating industry. A second-pass RO treatment strategy
was explored, addressing residual boric acid in the permeate and leveraging
solubility interactions to enhance its rejection, enabling water reuse.
Based on these findings, an RO designed for industrial application
was proposed for future scale-up and evaluation within a real-world
production environment.