Optimisation of biohydrometallurgical batch reactor process for copper extraction and recovery from non-pulverized waste printed circuit boards

The electronic waste is the fastest-growing solid waste all over the world. The printed circuit board (PCB), an essential part of all the electronic waste is a potential source of various metals thus known as Urban-mine. In this paper, a novel approach to enhance the extraction of copper from non-pulverized waste printed circuit boards (WPCBs) was carried out. WPCBs pre-treatment with NaOH for removal of the epoxy coating was optimized before the bioleaching process. The pretreatment resulted in the exposure of the metal present on WPCBs. Copper was extracted by two-step bioleaching process. In the first step ferric sulphate was biogenerated by Leptospirillum ferriphilum dominating iron oxidizing consortium with 1196.0 mg/L/h of average ferrous sulphate oxidation rate. In the second step, the biogenerated ferric iron was used for copper extraction from a single plate as well as from multiple plates in scale-up studies. In the scale-up study, 3 batches of eleven WPCB plates at a time were studied and an average 168 +/- 1.3 g copper was recovered at the end of the process, which corresponds to 99% leaching. The recovered copper was precipitated from the leachate by the cementation process using iron scrap and almost 99% copper was recovered after the process. The developed process shows the potential to be applied at commercial scale for recovery of metals and the management of electronic waste which leads to conservation of resources and environment.