Global and regional potential of wastewater as a water, nutrient and energy source

TLDR

Growing interest in recovering water, nutrients, and energy from municipal wastewater is driven by increasing volumes and advances in resource‑recovery technologies. The study aims to evaluate the global and regional potential of wastewater as water, nutrient, and energy sources, and to propose a step‑wise approach for high‑efficiency recovery that supports SDGs and climate‑change adaptation. Authors synthesize municipal wastewater data and calculate maximum theoretical amounts of water, nutrients, and energy to estimate this potential. They estimate that 380 billion m³ of wastewater is produced annually worldwide—five times the volume of water flowing through Niagara Falls—and that it contains 16.6 Tg of nitrogen, 3.0 Tg of phosphorus, and 6.3 Tg of potassium, enough to offset 13.4 % of global agricultural demand; the embedded energy could power 158 million households, and production is projected to rise 24 % by 2030 and 51 % by 2050.

Abstract

Abstract There is a proactive interest in recovering water, nutrients and energy from waste streams with the increase in municipal wastewater volumes and innovations in resource recovery. Based on the synthesis of wastewater data, this study provides insights into the global and regional “potential” of wastewater as water, nutrient and energy sources while acknowledging the limitations of current resource recovery opportunities and promoting efforts to fast‐track high‐efficiency returns. The study estimates suggest that, currently, 380 billion m 3 (m 3 = 1,000 L) of wastewater are produced annually across the world which is a volume five‐fold the volume of water passing through Niagara Falls annually. Wastewater production globally is expected to increase by 24% by 2030 and 51% by 2050 over the current level. Among major nutrients, 16.6 Tg (Tg = million metric ton) of nitrogen are embedded in wastewater produced worldwide annually; phosphorus stands at 3.0 Tg and potassium at 6.3 Tg. The full nutrient recovery from wastewater would offset 13.4% of the global demand for these nutrients in agriculture. Beyond nutrient recovery and economic gains, there are critical environmental benefits, such as minimizing eutrophication. At the energy front, the energy embedded in wastewater would be enough to provide electricity to 158 million households. These estimates and projections are based on the maximum theoretical amounts of water, nutrients and energy that exist in the reported municipal wastewater produced worldwide annually. Supporting resource recovery from wastewater will need a step‐wise approach to address a range of constraints to deliver a high rate of return in direct support of Sustainable Development Goals (SDG) 6, 7 and 12, but also other Goals, including adaptation to climate change and efforts in advancing “net‐zero” energy processes towards a green economy.