Cardiff University | Prifysgol Caerdydd ORCA
Online Research @ Cardiff 
WelshClear Cookie - decide language by browser settings

Bioremediation of wastewaters utilising iron oxide-bearing wastes

Al-Obaidi, Safaa 2021. Bioremediation of wastewaters utilising iron oxide-bearing wastes. PhD Thesis, Cardiff University.
Item availability restricted.

[thumbnail of PhD Thesis]
PDF (PhD Thesis) - Accepted Post-Print Version
Download (4MB) | Preview
[thumbnail of Cardiff University Electronic Publication Form] PDF (Cardiff University Electronic Publication Form) - Supplemental Material
Restricted to Repository staff only

Download (291kB)


Iron oxides bearing sludge, including mine water treatment sludge (MWT), a mix of mine water treatment and wastewater treatment sludge, herein termed mixed sludge (MX), and water treatment sludge (WT) were investigated as microbial substrates to remediate recalcitrant aromatic hydrocarbons in textile and BTEX bearing wastewaters. Also, these sludges were used to treat municipal wastewater. The concept of the experimental work is based on using iron oxide bearing sludges, which are abundance waste materials generated from mining activity and water treatment processes, to remediate industrial and municipal wastewaters using a practical and simple application. The textile wastewater experiments included three phases of work based on different influent recipe compounds and the types of iron oxides bearing sludge used as a column’s substrate. Dye decolourisation during textile wastewater experiments varied between 60 - 99 % during these phases. A maximum MWT adsorption capacity was 3.50 mg/g and the highest normalised methyl orange (MO) removal rate was 178 g/m3/day by MWT sludge. It was shown that the dye removal during these experiments was mostly due to biodegradation rather than adsorption. Furthermore, iron-reducing microorganisms and the affiliated bacteria in MWT sludge mineralised 3000 g/m3/day and 216 g/m3/day of the total influent carbon (TC) and total nitrogen (TN) during phase two as a maximum normalised removal rate. The indigenous MWT consortia degraded MO as a sole carbon source by reduction of the azo dye double bond as a first step then oxidation of the aromatic hydrocarbon ring. Furthermore, it was found that adding additional organic carbon as glycerol accelerated the MO decolourisation during textile wastewater experiment. In municipal wastewater experiment, iron oxides bearing sludge microbial community included iron-reducing bacteria and the affiliated genera efficiently degraded carbon and transform nitrogen contaminants. The highest normalised TC removal rate was 301 g/m3/day by MWT, and the highest normalised TN removal rate was 159 g/m3/day by MX columns. Anaerobic ammonium oxidation under iron-reducing condition (Feammox) in addition to anaerobic ammonium oxidation (Anammox), might be the main mechanisms for nitrogen transformation during municipal and textile wastewater treatments. In the BTEX bearing wastewater experiments, initial anoxic and II aerobic microcosms conditions were undertaken to degrade benzene, toluene, ethylbenzene, and xylene (BTEX) using iron oxides bearing sludge as substrates. The indigenous microbial community, including iron-reducing microorganisms, degraded BTEX as a sole carbon source more efficiently for the initial anoxic condition. The next-generation sequencing confirmed that iron-reducing bacteria, e.g., Geothrix, Geobacter Gallionella, Prevotella, Rhodoferax, and Clostridium were detected in most of the post-test sludge which were used in all wastewater experiments. Iron-reducing bacterial genera were affiliated with other bacterial species as a consortium. This consortium degraded azo dye by cleavage of the azo bond and the aromatic hydrocarbon ring without generating aromatic amines, and it mineralised the BTEX. It also degraded carbon and transform nitrogen contaminants during wastewater treatments. The microbial consortia that flourished in post-test sludge degraded recalcitrant wastewater contaminants as a sole carbon source to simplest compounds without pre-acclimatisation. The experimental work demonstrated that the iron oxide bearing sludge and their indigenous microbial consortia are feasible substrates to degrade recalcitrant wastewater contaminants to simplest compounds as a sole carbon source without pre-acclimatisation. It can be concluded that iron oxides bearing sludge can be used as reactive bioremediation media in a simple flow-through system to treat wastewater and groundwater pollutants with effective contaminant removal.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Engineering
Uncontrolled Keywords: Iron reducing bacteria; Bioremediation; Azo dye degradation; Aromatic amines mineralisation; wastewater treatment; textile wastewater treatment.
Date of First Compliant Deposit: 23 February 2021
Last Modified: 30 Oct 2021 01:20

Actions (repository staff only)

Edit Item Edit Item


Downloads per month over past year

View more statistics