Fighting the hidden threat: Antibiotic resistance in wastewater treatment
By Dr Muhammad Noor Hazwan Jusoh
Antibiotics, essential for combating illnesses in humans and animals, are more prevalent in our environment than most people realise. Beyond medical use, they permeate industries such as aquaculture, veterinary therapy, and stock farming.
However, up to 90 per cent of these antibiotics are not fully metabolised and are excreted in urine and faeces, making their way into wastewater treatment plants (WWTPs) through sewage systems. In some cases, they are even discharged directly into rivers when proper facilities for treating municipal effluents are lacking.
This widespread presence of antibiotics in wastewater has dire consequences. The diverse bacteria found in these waters can develop resistance when exposed to antibiotics, leading to the emergence of antibiotic-resistant bacteria (ARB). This process, known as Antimicrobial Resistance (AMR), involves the spread of antibiotic-resistant genes (ARGs) among bacterial populations.
WWTPs, which handle wastewater from residential, medical, industrial, and agricultural sources, are crucial battlegrounds in this fight. These plants are designed to remove harmful contaminants, yet they often fail to fully eliminate ARB and ARGs. Consequently, these resilient bacteria and their genes are released into aquatic ecosystems, posing a continuous threat to public health.
In tackling this issue, WWTPs employ a combination of physical and biological processes. Physical treatments, such as bar screening and sedimentation, remove suspended solids. Biological processes, leveraging microbial metabolism, break down complex organic compounds into less harmful substances. Techniques like the activated sludge process and rotating biological contactors play a key role in this phase.
Despite these efforts, conventional treatments often fall short in eradicating antibiotic compounds, including sulfonamides, tetracyclines, and macrolides, which persist at trace levels. To enhance effectiveness, advanced treatment methods such as UV disinfection, ozonation, and membrane filtration are employed, although they come with high costs and energy demands.
Even with these advanced methods, residual antibiotics and ARB can remain in treated wastewater. When this effluent is discharged into surface waters, it has the potential to spread resistance genes to other bacteria and pathogens, reducing the efficacy of antibiotics and raising healthcare costs due to more challenging infections.
To combat this, communities must take proactive steps. Implementing antibiotic stewardship programs can curtail unnecessary prescriptions and encourage responsible use. Educating the public about the dangers of overusing antibiotics and the importance of following prescribed treatments is crucial in raising awareness and promoting adherence.
Dr Muhammad Noor Hazwan Jusoh, a lecturer in the Department of Civil and Construction Engineering at Curtin University Malaysia, holds a PhD in civil engineering from Universiti Teknologi Malaysia (UTM). His research expertise includes water treatment, wastewater engineering, and environmental sustainability. Dr Muhammad Noor Hazwan has led national and international research projects and published extensively in peer-reviewed journals, book chapters, and conference proceedings. For more information, contact Dr Muhammad Noor Hazwan at mn.hazwan@curtin.edu.my.
