English abstract
Constructed wetlands have been proven effective in treating the significant amounts
of produced water generated from oil extraction operations. However, with the
increasing use of partially hydrolyzed polyacrylamide (HPAM) in enhancing oil
recovery, and its natural degradation into its toxic acrylamide (AM) monomer, the
negative impacts of AM on the biological processes of wetlands have been gaining
increased research attention. Microbial mats in wetlands play a key role in the
bioremediation of hydrocarbons present in produced water, and the effect of this AM
contamination on the mats is still understudied. This project aims to investigate the
impact of AM on microbial mats, and their potential for AM degradation under
aerobic and anaerobic conditions at different AM concentrations, using GC and
HPLC techniques, respectively. Additionally, AM degradation by pure bacterial and
algal strains was explored. Results showed that AM generated CO2 in the mat
treatment groups (500, 1000, and 2000 mg/L AM), indicating that AM was being
used as a carbon source. The mats were also found to degrade AM efficiently within
28 days of incubation under aerobic conditions, while very slow rates were observed
under anaerobic conditions. Aerobic mat incubations at 500 mg/L and 1000 mg/L
AM resulted in 95 ± 0.1% and 90 ± 10.6% AM degradation, respectively. Moreover,
independent growth of bacterial and algal isolates in AM revealed interesting
degradation efficiencies, where some strains have fully degraded AM up to 1000
mg/L after 7 days and 34 days, respectively. It was concluded that wetland microbial
mats adapt well to AM and could maintain their respiration and hydrocarbon
degradation activities in the field
