TY - JOUR
T1 - Wastewater Treatment for Carbon Dioxide Removal
AU - Masindi, Vhahangwele
AU - Foteinis, Spyros
AU - Renforth, Phil
AU - Chatzisymeon, Efthalia
N1 - Funding Information:
The authors of this manuscript would like to convey their sincere gratitude to Magalies Water (MW), University of South Africa (UNISA), University of Pretoria (UP), and the Council for Scientific and Industrial Research (CSIR) for extending their facilities toward the fulfillment of the objectives of this study. Funding was also provided from the European Union’s Horizon 2020 Research and Innovation Program under grant 869357 (project OceanNETs: Ocean-Based Negative Emission Technologies, analyzing the feasibility, risks, and cobenefits of ocean-based negative emission technologies for stabilizing the climate).
Publisher Copyright:
© 2023 The Authors. Published by American Chemical Society.
PY - 2023/10/31
Y1 - 2023/10/31
N2 - Wastewater treatment is notorious for its hefty carbon footprint, accounting for 1-2% of global greenhouse gas (GHG) emissions. Nonetheless, the treatment process itself could also present an innovative carbon dioxide removal (CDR) approach. Here, the calcium (Ca)-rich effluent of a phosphorus (P) recovery system from municipal wastewater (P recovered as calcium phosphate) was used for CDR. The effluent was bubbled with concentrated CO2, leading to its mineralization, i.e., CO2 stored as stable carbonate minerals. The chemical and microstructural properties of the newly formed minerals were ascertained by using state-of-the-art analytical techniques. FTIR identified CO3 bonds and carbonate stretching, XRF and SEM-EDX measured a high Ca concentration, and SEM imaging showed that Ca is well distributed, suggesting homogeneous formation. Furthermore, FIB-SEM revealed rhombohedral and needle-like structures and TEM revealed rod-like structures, indicating that calcium carbonate (CaCO3) was formed, while XRD suggested that this material mainly comprises aragonite and calcite. Results imply that high-quality CaCO3 was synthesized, which could be stored or valorized, while if atmospheric air is used for bubbling, a partial direct air capture (DAC) system could be achieved. The quality of the bubbled effluent was also improved, thus creating water reclamation and circular economy opportunities. Results are indicative of other alkaline Ca-rich wastewaters such as effluents or leachates from legacy iron and steel wastes (steel slags) that can possibly be used for CDR. Overall, it was identified that wastewater can be used for carbon mineralization and can greatly reduce the carbon footprint of the treatment process, thus establishing sustainable paradigms for the introduction of CDR in this sector.
AB - Wastewater treatment is notorious for its hefty carbon footprint, accounting for 1-2% of global greenhouse gas (GHG) emissions. Nonetheless, the treatment process itself could also present an innovative carbon dioxide removal (CDR) approach. Here, the calcium (Ca)-rich effluent of a phosphorus (P) recovery system from municipal wastewater (P recovered as calcium phosphate) was used for CDR. The effluent was bubbled with concentrated CO2, leading to its mineralization, i.e., CO2 stored as stable carbonate minerals. The chemical and microstructural properties of the newly formed minerals were ascertained by using state-of-the-art analytical techniques. FTIR identified CO3 bonds and carbonate stretching, XRF and SEM-EDX measured a high Ca concentration, and SEM imaging showed that Ca is well distributed, suggesting homogeneous formation. Furthermore, FIB-SEM revealed rhombohedral and needle-like structures and TEM revealed rod-like structures, indicating that calcium carbonate (CaCO3) was formed, while XRD suggested that this material mainly comprises aragonite and calcite. Results imply that high-quality CaCO3 was synthesized, which could be stored or valorized, while if atmospheric air is used for bubbling, a partial direct air capture (DAC) system could be achieved. The quality of the bubbled effluent was also improved, thus creating water reclamation and circular economy opportunities. Results are indicative of other alkaline Ca-rich wastewaters such as effluents or leachates from legacy iron and steel wastes (steel slags) that can possibly be used for CDR. Overall, it was identified that wastewater can be used for carbon mineralization and can greatly reduce the carbon footprint of the treatment process, thus establishing sustainable paradigms for the introduction of CDR in this sector.
UR - http://www.scopus.com/inward/record.url?scp=85176747629&partnerID=8YFLogxK
U2 - 10.1021/acsomega.3c04231
DO - 10.1021/acsomega.3c04231
M3 - Article
C2 - 37929097
AN - SCOPUS:85176747629
SN - 2470-1343
VL - 8
SP - 40251
EP - 40259
JO - ACS Omega
JF - ACS Omega
IS - 43
ER -
