A new international study aims to provide insights into the global and regional potential of the some 380 billion m3 of wastewater produced annually around the world as water, nutrient and energy sources, as well as the economic returns and environmental benefits its proper management could represent.
The paper, Global and regional potential of wastewater as a water, nutrient and energy source, offers important approximations of global and regional wastewater volumes and insights into its potential benefits, despite the fact that in many countries official data on wastewater is often scattered, poorly monitored and reported, or simply unavailable.
Wastewater production globally is expected to increase by 24% by 2030 and 51% by 2050 over the current level, the paper states. The potential for recovering these resources from waste streams remains under-explored, the paper’s authors argue; however, they also note a positive shift towards research and practice supporting collection, treatment and fit-for-purpose productive use of treated municipal wastewater.
“Municipal wastewater is of increasing interest within the Water–Energy–Food nexus, given that it allows the recovery of all three resources – water, energy and nutrients for crop production,” the paper’s introduction states. “It also provides wastewater treatment with an additional value proposition aside from the protection of our aquatic environment.”
While acknowledging the limitations of current resource recovery opportunities and promoting efforts to fast-track high-efficiency returns, the new study, funded by the Government of Canada and the UN University Institute for Water, Environment and Health provides estimates and projections based on a new analysis of the world’s total annual wastewater production. The study is published by the Wiley in Natural Resources Forum, a UN Sustainable Development Journal.
Among major nutrients, annual global wastewater production contains 16.6 Tg (Tg = 1 million metric tons) of nitrogen; 3.0 Tg of phosphorus; and 6.3 Tg of potassium. The full nutrient recovery from wastewater would offset 13.4% of the global demand for these nutrients in agriculture, the study found.
Based on reasonable global demand, the recovery of these nutrients from wastewater could result in revenue generation of $13.6 billion globally, with $9 billion from the recovery of nitrogen, $2.3 billion from phosphorus and $2.3 billion from potassium.
Based on 53 wastewater quality datasets from across the world, the study’s authors estimated the average concentrations of nutrients in wastewater with nitrogen (43.7 mg/L), phosphorus (7.8 mg/L), and potassium (16.5 mg/L).
“Wastewater is a rich source of organic matter and thus a carrier of chemical energy,” the paper states. “The organic compounds present in wastewater can be converted into methane-rich biogas via anaerobic digestion.”