Sustainable remediation and redevelopment of brownfield sites

Widespread pollution from industrial activities has driven land degradation with detrimental human health effects, especially in urban areas. Remediation and redevelopment of the estimated 5 million brownfield sites globally is needed to support the sustainable transition and increase urban ecosystem services, but many traditional strategies are often environmentally harmful. In this Review, we outline sustainable remediation strategies for the clean-up of contaminated soil and groundwater at brownfield sites. Conventional remediation strategies, such as dig and haul, or pump and treat, ignore secondary environmental burdens and socioeconomic impacts; over their life cycle, some strategies are more detrimental than taking no action. Sustainable remediation technologies, such as sustainable immobilization, low-impact bioremediation, new forms of in-situ chemical treatment and innovative passive barriers, can substantially reduce the environmental footprint of remediation and maximize overall net benefits. Compared with traditional methods, they can typically reduce the life-cycle greenhouse gas emissions by ~50–80%. Integrating remediation with redevelopment through nature-based solutions and sustainable energy systems could further increase the socioeconomic benefit, while providing carbon sequestration or green energy. The long-term resilience of these systems still needs to be understood, and ethics and equality must be quantified, to ensure that these systems are robust and just.