The potential of wastewater treatment on carbon storage through ocean alkalinity enhancement

Ocean alkalinity enhancement (OAE) implemented through wastewater
treatment plants increases the alkalinity of the effluents and discharges
them into the ocean, referred to as wastewater-based OAE. However, the
alkalization capability and its carbon storage stability when adding
alkaline minerals to wastewater treatment are uncertain. In this study,
total alkalinity was enhanced to over 10 mmol kg−1 and phosphate removal
was improved when we added olivine to wastewater in a laboratory setting.
The alkalization rate by olivine dissolution in aerobically treated
wastewater was 20 times higher than in seawater. We estimated the
potential of carbon sequestration through wastewater-based OAE to be 18.8
± 6.0 Tg CO2 per year globally, with notable potential in the 20°N to 60°N
region.