REDUCTION OF CARBON EMISSIONS IN A MEDITERRANEAN URBAN WASTEWATER TREATMENT PLANT

In the last few decades, with the rapid growth of population, and more than half of them living in cities, the urban wastewater treatment has become a big challenge that consumes many resources, namely energy. In a climate change scenario, the Mediterranean region is facing more frequent water scarc...

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Bibliographic Details
Published in:WIT Transactions on Ecology and the Environment 2021-07, Vol.251, p.87
Main Authors: MANUELA MOREIRA DA SILVA, CRISTOVÃO, LUÍS, Marinho, Duarte, Esteves, Eduardo, Fraqueza, Gil, MARTINS, ANTÓNIO
Format: Article
Language:English
Subjects:
Activated carbon
Activated sludge
Aeration
Ammonia
Biological activity
Carbon dioxide
Chemical oxygen demand
Climate change
Control systems
Denitrification
Drinking water
E coli
Effluent standards
Effluents
Emissions
Energy consumption
Nitrification
Organic matter
Oxidation
Quality standards
Real time
Reduction
Seasonal variations
Treated water
Wastewater treatment
Wastewater treatment plants
Water reuse
Water scarcity
Water treatment
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Summary:In the last few decades, with the rapid growth of population, and more than half of them living in cities, the urban wastewater treatment has become a big challenge that consumes many resources, namely energy. In a climate change scenario, the Mediterranean region is facing more frequent water scarcity periods, and urban water reuse can be a solution, at least for supplying some non-potable water uses. In this context, the performance of urban wastewater treatment plants (WWTP) is of utter importance, to produce environmentally safe treated water while reducing energy consumption and carbon emissions (CE). Activated sludge is the biological process most widely used in wastewater treatment and requires aeration systems in order to promote the oxidation of organic matter and ammonia. It is known that the energy consumed in the aeration processes is of major importance for the global WWTP CE. This study was carried out in a WWTP in southern Portugal, wherein an aeration control system that responds in real time to ammonia and nitrate concentrations was tested. The system is set to optimize the duration of the aerated and non-aerated periods, for nitrification and denitrification. During the experimental period, BOD, COD, Escherichia coli, TN and TP were monitored in the treated effluent, in order to verify the quality standards that allow its reuse. The aeration control system contributed to a decrease of about 13% of the specific energy consumption, when compared with the corresponding period in previous years, representing a CE reduction of about 1.2 t CO2 eq, during the experimental period. The treated effluent maintained its high quality standards and can be used, for example, in agricultural irrigation of local crops. Aeration control systems reacting in real time can have an important role to decrease CE of urban WWTPs; however, further research is needed, including more WWTPs and analyzing seasonal variations in energy consumption over the year.
ISSN:1746-448X
1743-3541
DOI:10.2495/WS210091