Resource utilization of wastewater generated during the etching process in electrode foil production: An engineering case study

Abstract

The etching process in electrode foil production generates vast quantities of low-concentration acidic rinse water and high-concentration waste acid, posing severe environmental risks. This study presents an integrated engineering solution combining precipitation, ultrafiltration with ceramic membranes (UF), two-stage reverse osmosis (RO), resin softening, and advanced oxidation to achieve near-zero wastewater discharge. The system treats 1960 m³/d rinse water and 300 m³/d waste acid, achieving >95 % water recovery with effluent quality (TDS ≤200 mg/L, pH 6–9) meeting industrial reuse standards. Crucially, waste streams are valorized: RO concentrate, and waste acid are converted into 40,000 tons/year of high-purity coagulants (solid aluminum sulfate and sodium aluminum sulfate), compliant with GB/T 31060-2014 Class I standards. Economically, daily operational costs (1.224 million CNY) are offset by revenues from water reuse and coagulant sales (1.923 million CNY/day), yielding ∼20.97 million CNY/year net profit. This circular approach demonstrates scalable resource recovery simultaneously reclaiming water, acid, salts, and aluminum while addressing water scarcity and pollution in electrode foil manufacturing.