Water reuse nexus with resource recovery: On the fluidized-bed homogeneous crystallization of copper and phosphate from semiconductor wastewater

Green and sustainable strategies aim for the development of manufacturing processes that maximize the use of resources instigating semiconductor industry to adopt zero-liquid discharge policies. Complexity and variations of semiconductor wastewater effluents opens an opportunity for resource recovery (i.e. copper from chemical-mechanical polishing) including heavy metals and inorganic ions (i.e. phosphate from acid cleaning). This present work demonstrates the capabilities of fluidized-bed homogeneous crystallization as treatment technology to process water effluents for industrial reuse while simultaneously recovering precious resources such as copper and phosphate. Operational variables have been optimized considering the combination of both effluents to produce high quality copper phosphate granules. The optimum copper percentage removal and crystallization efficiency were 99% and 96.07% respectively obtained at pH_e 6.0–6.5, 1.25 [PO₄ ⁻³]_in/[Cu²⁺]_in at hydraulic retention time 22.5 min with 0.51 kg Cu²⁺/m² h and fixed [Cu²⁺]_in loading of 4.5 mM. The recovered crystals have an average particle diameter of ∼1 mm and were characterized identifying libethenite (Cu₂PO₄OH) as main recovered products.