Energy Efficiency Assessment of Wastewater Treatment Plants: Analyzing Energy Consumption and Biogas Recovery Potential

Artur Mielcarek (), Roksana Lubińska, Joanna Rodziewicz and Wojciech Janczukowicz
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Artur Mielcarek: Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Warszawska St. 117a, 10-719 Olsztyn, Poland
Roksana Lubińska: Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Warszawska St. 117a, 10-719 Olsztyn, Poland
Joanna Rodziewicz: Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Warszawska St. 117a, 10-719 Olsztyn, Poland
Wojciech Janczukowicz: Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Warszawska St. 117a, 10-719 Olsztyn, Poland

Energies, 2025, vol. 18, issue 19, 1-16

Abstract: Directive (EU) 2024/3019 on urban wastewater treatment requires municipal wastewater treatment plants (WWTPs) to achieve energy neutrality by 2045. This study assessed the energy efficiency of a WWTP in central Poland over eight years (2015–2022), considering influent variability, electricity use and cost, and biogas recovery. The facility served 41,951–44,506 inhabitants, with treated wastewater volumes of 3.08–3.93 million m 3 /year and a real population equivalent (PE) of 86,602–220,459. Over the study period, the specific energy demand remained stable at 0.92–1.20 kWh/m 3 (average 1.04 ± 0.09 kWh/m 3 ), equivalent to 17.4–36.3 kWh/PE∙year. Energy efficiency indicators (EEIs) per pollutant load removed averaged 1.12 ± 0.28 kWh/kgBODrem, 0.53 ± 0.12 kWh/kgCODrem, 1.18 ± 0.36 kWh/kgTSSrem, 12.1 ± 1.5 kWh/kgTNrem, and 62.3 ± 11.7 kWh/kgTPrem. EEI per cubic meter of treated wastewater proved to be the most reliable metric for predicting energy demand under variable influent conditions. Electricity costs represented 4.48–13.92% of the total treatment costs, whereas co-generation from sludge-derived biogas covered 18.1–68.4% (average 40.8 ± 13.8%) of the total electricity demand. Recommended pathways to energy neutrality include co-digestion with external substrates, improving anaerobic digestion efficiency, integrating photovoltaics, and optimizing electricity use. Despite fluctuations in influent quality and load, the ultimate effluent quality consistently complied with legal requirements, except for isolated cases of exceeded phosphorus levels.

Keywords: energy consumption; wastewater treatment; WWTP energy neutrality; EU wastewater directive; wastewater treatment costs; energy recovery; municipal wastewater quality (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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