Environmental assessment of emerging contaminants towards safer wastewater reuse

Wastewater reuse allows turning source-separated and municipal (domestic) wastewater into precious resources, such as, in the form of fertilisers or as an alternative source of water supply. However, even after treatment, human wastewater can still contain hazardous chemical and microbial contaminants, which pose a challenge to safe reuse in the circular economy. Reuse of treated wastewater, through applications in agricultural fields as fertilisers or irrigation water, can therefore be a vector of contamination to recipient environmental compartments, e.g., from soil to freshwater bodies (surface water, groundwater) and biota. Humans may be exposed to these contaminants via food consumption due to their potential uptake by crops in agricultural fields fertilised or irrigated with wastewater, and via water consumption when wastewater is directly reused for drinking water production, or indirectly, when wastewater is discharged and mixed with freshwater as the source of drinking water production. The antibiotic resistance determinant, such as antibiotics, their related (bio)transformation products, and antibiotic resistance genes (ARGs), is a group of emerging contaminants of great concern as they can promote the emergence of antibiotic resistance that is considered as a major human and animal health threat in this century. The environmental behaviour, fate and toxicity of these contaminants is poorly understood, so their consequences to the environmental health are not well assessed. There is a clear need for evaluating whether wastewater reuse is safe regarding these emerging threats, as source-separated and municipal wastewater are wastes increasingly considered as an essential resource for many purposes.

My research goal is to advance our knowledge on the environmental fate and impacts of emerging contaminants resulting from the discharge and reuse of source-separated and municipal wastewater. The general aims are to establish innovative analytical strategies for comprehensive characterisation of these contaminants, to understand their environmental behaviour, from sources to recipients, and to evaluate efficiencies for available treatment techniques aiming at minimising the spread of the contaminants. In my lecture, I will present two case studies from my ongoing projects relating to these challenges. The first project aims to assess the environmental transport and distribution of emerging contaminants using blackwater as fertilisers in agricultural settings. The other one aims to examine and minimise emerging contaminants in domestic wastewater from on-site sewage facilities and their spread to groundwater, which is a source of drinking water production. The case studies represent unique examples of research-based investigations on the potential emergence and transmission of antibiotic resistance in the environment associated with wastewater discharges and reuse. The projects involve collaborations with researchers from SLU and abroad as well as stakeholders (municipalities and the Swedish Geological Survey). The research works will help the society to reach national and international environmental quality goals concerning water quality, resources and a non-toxic environment, such as several of the United Nations Sustainable Development Goals (SDGs) and the Swedish Environmental Quality Objectives.