Investigating the bioattenuation of emerging organic contaminants in managed groundwater environments to protect human health and the environment

Objectives
The discharge of stormwater and wastewater from urban environments is increasing at a global scale while population growth and climate change are concurrently placing many cities under increasing water stress. Managed aquifer recharge (MAR), where water is captured and stored in controlled aquifers underground, presents an opportunity to reuse this stormwater and wastewater. Many emerging organic contaminants (EOCs), such as pesticides, pharmaceuticals and firefighting foams are becoming ubiquitous in the environment, including in the water used to recharge aquifers. This is leading to increased concern regarding the risks that water from MAR could pose to public health.

Design and Methodology

Natural biological processes, referred to here as bioattenuation, are often key to EOC removal in water environments, either directly through biodegradation or indirectly by facilitating suitable conditions for chemical degradation or sorption to take place. This study utilises novel batch and column experiments to determine how factors such as biofilm formation and water composition affect EOC bioattenuation. Authentic aquifer materials were used in experiments. Reverse-phase HPLC was used to quantify EOC concentrations and CLSM microscopy to visualise and quantify biofilm formation.

Original data and results
Experimental data from batch studies display how biofilm effects the material’s adsorptive properties. Column experiments contrast how transport behaviour changed under three experimental conditions: biological activity suppressed, standard operating conditions by conditioning with stormwater, and enhanced biological activity by conditioning with nutrient rich wastewater. By contrasting these three experimental conditions, it will be possible to discern the physical, chemical and biological factors which affect transport of EOCs in MAR environments.

Conclusion
By better understanding the fate and transport of organic contaminants in MAR schemes, better informed management decisions can be made. This in turn assists in ensuring this important water reuse solution can be implemented in a safe and sustainable manner.