Safe reuse of treated produced water outside oil and gas fields? A review of current practices, challenges, opportunities, and a risk-based pathway for produced water treatment and fit-for-purpose reuse

The oil and gas (O&G) industry has expanded significantly and brought to the surface large volumes of saline water called produced water (PW), which comprises of underground formation water, injection water, and chemical additives used during extraction and production. PW is traditionally managed via injection wells, evaporation/seepage pits, or recycling for on-site operations. There is increasing interest in PW treatment and reuse outside O&G fields due to freshwater scarcity and concerns about seismic events linked to deep-well injection. Adopting treated PW for reuse outside the O&G sector needs to address the challenges of complex water chemistry, limited toxicity data, and knowledge gaps for appropriate regulatory responses, including risk assessment frameworks on human health and the environment, socio-technical-economic assessments of treatment and reuse applications, and long-term demonstrations and monitoring of fit-for-purpose reuse. This opinion paper proposes a holistic, state-of-the-science pathway for PW treatment, management, and fit-for-purpose reuse outside O&G fields.