Efficiency assessment of pure Fe oxidizing microorganisms in iron supplemented and non-supplemented medium and pure S oxidizing microorganisms for bioleaching of mobile phone printed circuit boards

The microbial culture as well as the components of the bioleaching medium affects the efficiency of microbial leaching. The present study on mobile phone printed circuit boards (MPPCBs) was conducted to know that whether the addition of energy source is required during the microbial leaching or microorganisms can utilize the iron (Fe) content of the MPPCB. The study was conducted with pure Fe oxidizers in Fe supplemented (9g/L, pure Fe 9K), non-supplemented (0g/L, pure Fe 0K) medium and pure sulfur (S) oxidizers supplemented with 3g/L of elemental sulfur (Pure S 3g/L S-0). The copper (Cu) content of the feed material was 26.3% (w/w) by X-Ray Fluorescence (XRF) spectroscopy. The Cu recovery in pure Fe 0K and pure Fe 9K was 100% while with pure S oxidizers it was 39.41%. The acid consumption in pure Fe 0K and pure Fe 9K was 579.65kg/ton and 559.05kg/ton respectively. The bioleaching rate of Cu was 0.128g/L/h, 0.075g/L/h and 0.023g/l/h in order of pure Fe 9K> pure Fe 0K>pure S. Bioleaching with pure Fe oxidizers in 0K medium was found to be efficient and economical in terms of metal recovery and acid consumption, whereas, bioleaching with pure Fe 9K showed the maximum Cu leaching rate. The Cu recovery was same in both Fe supplemented and non-supplemented medium and microorganisms can utilize the Fe present in feed (PCB) itself.