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., , , # **The potential of wastewater treatment on carbon storage through ocean alkalinity enhancement**

[https://doi.org/10.5061/dryad.2547d7x2d](https://doi.org/10.5061/dryad.2547d7x2d)

**Description of the data and file structure**

HydroWASTE (Macedo et al., 2022) has supplied a spatially explicit global database of wastewater treatment plants (WWTPs), with 0.14 km3 day−1 of discharge from the 9,480 WWTPs located within 10 km of the ocean and with outfalls in the sea.

Salinity, dissolved inorganic carbon, and total alkalinity levels in seawater near the WWTP outlets were from the Ocean Carbon and Acidification Data System (OCADS) (Jiang et al., 2023).

Lehmann et al., 2023 and Cai et al., 2008 reported total alkalinities in rivers across latitudes.

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