Fungal bioleaching of aluminum, iron & titanium from coal fly ash using Aspergillus niger NBRC 31125

• Main Author: Querido, John Gabriel R.
• Format: text
• Language: English
• Published: Animo Repository 2016
• Subjects: Bacterial leaching; Leaching; Fly ash
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/5742
• Institution: De La Salle University

Global production of coal ash, composed of fly ash and bottom coming from coal fired power plants, reached 780 million tons while the utilization rate for it is roughly 53.5% which means there are other ways for it to be used like using it as a secondary source to leach out metals present within it. Bioleaching process has several advantages including environment friendly, high heavy metals removal, simple operation & cheap to maintain, no raw material composition, etc. Within this process, heterotrophic fungi are an interesting research because it has not been used as widely as bacteria but it has several advantages including consumption of organic carbon source, can survive at high pH, can survive at wide temperature range of 25-40 °C and could tolerate presence of metals. Coal fly ash is the material to be tested to see what metals can be recovered since it could bring economic value based on metals recovery. Since there is not much research conducted especially using Aspergillus niger NBRC 31125 on coal fly ash, the parameters to be tested are sucrose concentration of 1, 2.5 and 4 g/200 ml, 1, 3, 5 g of coal fly ash loading of introduced to the system and bioleaching time (1, 3 and 5 days) for the bioleaching process which could affect the extraction of % aluminum, % iron and % titanium. This study was conducted in several 300 ml Erlenmeyer flask with varying sucrose concentration, coal fly ash loading and placed in a shaker with constant temperature of 30 °C and 120 rpm. The pH of the system was monitored using Horiba pH meter and metal concentration is monitored using Seiko Instruments Inc. SPS7800 Plasma Spectrometer. In % Al leached, highest yield is 23.16% with sucrose concentration of 2.5 g/200 ml, coal fly ash loading of 1 g at bioleaching time of 1 day. In % Fe & Ti leached, highest yields are 78.53% and 68.41% respectively with sucrose concentration of 4 g/200 ml, coal fly ash loading of 1 g and 5 days of bioleaching time. Based from the Design Expert Version 10 software; sucrose concentration (g/200 ml), coal fly ash loading (g) and bioleaching time (day) are significant factors on the bioleaching process of coal fly ash using Aspergillus niger NBRC 31125. Comparison of bioleaching and chemical leaching and it shows mixed results depending on specific metals to be extracted.