Du, Tianhao; (2024) Remediation of acid mine drainage by using a consortium of algae, biochar and bacteria. Doctoral thesis (Ph.D), UCL (University College London).

Text Tianhao Du_PhD Thesis.pdf - Accepted Version Access restricted to UCL open access staff until 1 November 2025. Download (31MB)

Abstract

Acid mine drainage (AMD) is a severe issue that causes harmful environmental impacts. AMD contains high concentrations of heavy metals and has high acidity, making it toxic to plants, animals, and humans. Traditional treatments for AMD have been widely used for a long time; however, they have limitations, including low efficiency and the need for large areas. Consequently, bio-based materials such as biochar, algae, and bacteria are being developed to replace traditional treatment methods. This thesis investigates the removal of zinc from naturally occurring AMD using biochar, indigenous algae, sulphate-reducing bacteria (SRB), and consortia of algae-biochar, biochar-SRB, and algae-biochar-SRB. The batch experiments were conducted on a laboratory scale, and the zinc concentrations were analysed using inductively coupled plasma-optical emission spectrometry. The potential mechanisms of the removal processes by different materials were elucidated by analysing the absorbents before and after the removal process using scanning electron microscopy with energy dispersive X-ray spectroscopy and Fourier-transform infrared spectroscopy and by using kinetics models and removal equilibrium isotherm models based on the zinc removal results. The results showed that biochar produced from wheat straw pellets at 550˚C and Micractinium sp. exhibited superior zinc removal efficiencies of 93.45% up to 350 mg L-1 and 97.20% up to 50 mg L-1, respectively. For the SRB, simultaneous removal of zinc and sulphates was observed, with removal efficiencies ranging from 83.9% to 99.50% for zinc concentrations of 7.5 to 50 mg L-1 and from 30.4% to 34.4% for SO42- concentrations of 1400 mg L-1, respectively. Regarding the consortia, algae-biochar, biochar-SRB, and algae-biochar-SRB consortia exhibited removal efficiencies approximately 15% to 20% higher compared to the mono-absorbent method. Mechanism analysis results indicated that the precipitation of zinc by functional groups played a dominant role in zinc removal by biochar and algae. The main mechanism of zinc removal by SRB was the generation of insoluble ZnS. When using consortia to remove zinc from AMD, the mechanisms primarily involved an integration of all the materials. During the removal process, biochar served a protective role for biological material as well as absorbents to remove zinc. Meanwhile, algae and SRB provided nutrients to each other and facilitated metabolism in AMD to achieve higher removal efficiency. Therefore, using consortia formed by two or three algae, biochar, and SRB as an AMD remediation method is a novel, effective, and feasible approach that warrants further study and application in practice.

Download activity - last month

Export as CSVXMLJSON

Download activity - last 12 months

Export as JSONXMLCSV

Downloads by country - last 12 months

Export as JSONCSVXML

Archive Staff Only

View Item