Related Experiment Videos
Bioleaching of spent refinery processing catalyst using Aspergillus niger with high-yield oxalic acid
Deenan Santhiya1, Yen-Peng Ting
1Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge Crescent, Singapore 119260, Singapore.
Journal of Biotechnology
|January 25, 2005
Summary
This study shows Aspergillus niger can bioleach metals from spent refinery catalysts. Stimulating oxalic acid production with MES buffer accelerated metal extraction, particularly for molybdenum.
Area of Science:
- Biotechnology and Bioengineering
- Environmental Science and Engineering
- Materials Science and Engineering
Background:
- Spent refinery catalysts contain valuable heavy metals like aluminum, nickel, and molybdenum.
- Traditional disposal methods for spent catalysts pose environmental risks.
- Bioleaching offers a sustainable alternative for metal recovery from industrial waste.
Purpose of the Study:
- To investigate the bioleaching efficiency of Aspergillus niger for metal extraction from spent refinery catalysts.
- To evaluate the impact of catalyst particle size and pulp density on metal recovery.
- To explore the use of MES buffer to enhance organic acid excretion and accelerate bioleaching.
Main Methods:
- Physical and chemical characterization of spent refinery catalyst.
- Bioleaching experiments using Aspergillus niger with varying catalyst particle sizes and pulp densities.
- Monitoring biomass dry weight, pH, and organic acid excretion.
- Analysis of heavy metal concentrations in leach liquor using ICP-OES or similar techniques.
- Comparative study with and without MES buffer to assess its effect on metal extraction.
Main Results:
- Spent catalyst contained significant amounts of Al (33.3%), Ni (6.09%), and Mo (13.72%).
- Decreasing catalyst particle size (<37 microm) increased oxalic acid secretion and metal extraction.
- Highest metal recovery achieved: 54.5% Al, 58.2% Ni, and 82.3% Mo in 60 days.
- MES buffer stimulation significantly accelerated metal extraction, achieving comparable results in half the time.
- Buffered cultures showed significantly higher Mo extraction compared to non-buffered cultures.
Conclusions:
- Aspergillus niger is effective in bioleaching valuable metals from spent refinery catalysts.
- Optimizing particle size and using buffer-stimulated organic acid excretion can enhance bioleaching efficiency.
- Bioleaching presents a viable and eco-friendly method for metal resource recovery from industrial waste.