From wastewater to renewable energy production: Opportunities and challenges in mid-sized cities in Latin America and the Caribbean

The adoption of circular economy principles for methane recovery in wastewater treatment plants is already widespread in most mega-cities of Latin America and the Caribbean. The next step is to promote the adoption of this technology in intermediate wastewater treatment plants for which, this paper estimates its economic and environmental impacts. It does so by calculating the benefits from the methane recovery and electricity generation in plants that together serve 33 million people, distributed in the region, since they are from Bolivia, Colombia, Costa Rica, Mexico, and Peru. The results show an estimated cost of USD $251 million required for these investments, or USD $7.6 person equivalent (p.e.). These investments would allow obtaining incomes for 20 years of USD $10.2 p.e., representing a benefit/cost ratio of 1.34. Regarding environmental benefits, an 88% reduction in methane emissions into the atmosphere would be achieved, equivalent to a third of Nicaragua's total emissions in 2018. Thus, the article shows that this type of investment is feasible in intermediate plants. This is essential to accelerate the achievement of both SDG 6 and seven targets but requires innovative governance as well as access to finance and technological support. One main conclusion is that these endeavors are at the heart of setting standards that allow societies to live within planetary limits.