Emerging contaminants are newly recognized substances that pose potential risks to the environment and human health. These include pharmaceuticals, personal care products, endocrine disruptors, microplastics, and PFAS. They come from various sources like households, industries, and agriculture.

Managing emerging contaminants is challenging due to detection difficulties and limitations of conventional treatment methods. Advanced technologies are needed for effective removal, but they come with higher costs. Incomplete removal and formation of harmful byproducts during treatment are ongoing concerns.

Emerging Contaminants

Definition of emerging contaminants

• Substances recently discovered or recognized as potential environmental or public health risks
• Not currently regulated or undergoing the process of establishing regulatory guidelines
• Examples include pharmaceuticals and personal care products (PPCPs) (antibiotics, hormones, painkillers, cosmetic ingredients), endocrine-disrupting compounds (EDCs) (BPA, phthalates, certain pesticides), microplastics (tiny plastic particles < 5 mm), and per- and polyfluoroalkyl substances (PFAS) (used in non-stick coatings, stain-resistant fabrics, firefighting foams)

Sources of emerging contaminants

• Domestic sources introduce emerging contaminants through human excretion of PPCPs and improper disposal of unused medications down the drain
• Industrial sources contribute via manufacturing processes that use or produce emerging contaminants and leaching from landfills containing industrial waste
• Agricultural sources add emerging contaminants through runoff from fields treated with pesticides and veterinary pharmaceuticals
• Pathways include direct release into sewer systems from households and industries, stormwater runoff carrying contaminants from surfaces into wastewater collection systems, and infiltration of contaminated groundwater into sewer lines

Impacts of emerging contaminants

• Environmental impacts involve accumulation in aquatic ecosystems, leading to adverse effects on aquatic life such as endocrine disruption in fish and other organisms and developmental and reproductive issues in exposed wildlife
• Bioaccumulation and biomagnification in the food chain result in higher concentrations of contaminants in top predators
• Human health impacts occur through exposure via drinking water, food, and direct contact with contaminated water
• Potential risks include endocrine disruption affecting hormone balance and development, antibiotic resistance due to exposure to low levels of antibiotics, and long-term effects of chronic exposure to mixtures of contaminants

Challenges in managing emerging contaminants

• Detection and monitoring challenges arise from low concentrations (parts per trillion or parts per billion) making detection difficult, lack of standardized analytical methods for many emerging contaminants, and a continuously evolving list of contaminants to monitor
• Removal challenges in wastewater treatment stem from conventional treatment processes not designed to remove emerging contaminants, with many contaminants persisting through primary and secondary treatment
• Advanced treatment technologies required for effective removal, such as ozonation, advanced oxidation processes, activated carbon adsorption, and membrane filtration, come with higher costs and energy requirements
• Incomplete removal may still result in the release of contaminants into the environment
• Formation of potentially harmful transformation products during treatment processes poses additional challenges