Food Waste-Assisted Metal Extraction from Printed Circuit Boards: The Aspergillus niger Route
Carlotta Alias1, Daniela Bulgari2, Fabjola Bilo3
1B+LabNet-Environmental Sustainability Lab, University of Brescia, Via Branze 45, 25123 Brescia, Italy.
Microorganisms
|April 30, 2021
Summary
This study presents a novel, low-energy process using food waste to produce citric acid (CA) for extracting metals from electronic waste. This sustainable method efficiently recovers valuable metals like tin and iron from WPCBs.
Area of Science:
- Biotechnology
- Environmental Science
- Materials Science
Background:
- Urban waste valorization is crucial for sustainability and affordability.
- Electronic waste, particularly waste printed circuit boards (WPCBs), poses significant environmental challenges.
- Traditional metal extraction methods often involve harsh chemicals and energy-intensive processes.
Purpose of the Study:
- To develop a low-energy, eco-designed process for urban waste valorization.
- To produce citric acid (CA) from urban food waste using solid-state fermentation.
- To investigate the efficacy of biologically produced CA in extracting metals from WPCBs.
Main Methods:
- Solid-state fermentation of urban food waste by *Aspergillus niger* NRRL 334 to produce citric acid.
- Utilizing the biologically produced CA solution to leach metals from waste printed circuit boards (WPCBs).
- Comparing the metal leaching efficiency of biological CA with commercial CA.
Main Results:
- Citric acid (CA) was produced with a yield of 20.50 mg/g from urban food waste.
- The biological CA solution effectively leached metals from WPCBs, comparable to commercial CA.
- Tin (Sn) and Iron (Fe) were the most leached metals, with notable recovery of Nickel (Ni).
- This process achieved metal extraction without pre-treatment of WPCBs and without sugar supplementation for *A. niger*.
Conclusions:
- A novel, sustainable, and low-energy pathway for urban waste valorization and metal recovery from e-waste has been established.
- Citric acid produced via solid-state fermentation of waste materials can be effectively used for metal extraction.
- This green approach offers a promising alternative for recovering valuable metals from electronic waste.
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