Energy Consumption and Carbon Footprint of Greek Wastewater Treatment Plants

Nikos Goliopoulos,Christos Kounadis,Constantinos Noutsopoulos,Argyri Dimopoulou,Daniel Mamais

doi:10.3390/w14030320

Abstract

Wastewater treatment plants (WWTPs) exhibit significant energy consumption and produce large amounts of Greenhouse Gas emissions (GHG emissions). Energy efficiency and reduction in GHG emissions in WWTPs have become important issues, especially in view of the climate crisis. The core objective of this work is to assess the energy and carbon footprint of Greek WWTPs and to propose methods to improve energy efficiency and reduce GHG emissions. Data were collected from 31 Greek WWTPs with an average treatment capacity between 250 and 3,650,000 population equivalents (PE). The total population served by the 31 WWTPs was over 6,000,000, which is more than half of the population in Greece with access to WWTPs. Based on the results, the annual average energy consumption for small, medium and large WWTPs equals 137 kWh/PE, 48 kWh/PE and 32 kWh/PE, respectively. Accordingly, annual average GHG emissions, both biogenic and non-biogenic in small, medium and large WWTPs are equal to 207 kgCO2e/PE, 144 kgCO2e/PE and 89 kgCO2e/PE, respectively. Annual average on-site GHG emissions are equal to 56.5 kgCO2e/PE, while the average off-site GHG emissions account for 16.9 kgCO2e/PE. Based on the results, acceptable and attainable targets for WWTPs energy consumption and GHG emissions are proposed.

Highlights

Academic Editor: Xuliang ZhuangWWTPs are traditionally designed to achieve effluent requirements and prevent pollution of receiving water bodies
The present study aims at presenting a holistic overview of the Greek WWTPs energy consumption and greenhouse gas emissions (GHG) emissions and proposes equations to calculate the acceptable level of energy consumption and GHG emissions based on the capacity of a plant
Studies for the optimization of energy efficiency of WWTPs have been carried out for decades, but the climate crisis is making the reduction in energy consumption and GHG

Summary

Introduction

Academic Editor: Xuliang ZhuangWWTPs are traditionally designed to achieve effluent requirements and prevent pollution of receiving water bodies. During the last few years, energy-saving and energy efficiency are progressively becoming more urgent issues, mainly due to the problems associated with the climate crisis [1]. In view of this pressure, the wastewater industry is urged to face such challenges by adopting more sustainable practices such as the reduction in energy consumption and greenhouse gases emissions [2]. WWTPs are important energy consumers with an estimated 3–4% share of total U.S. electricity consumption attributed to the water industry [4]. The average annual energy consumption in WWTPs in the USA is approximately 29 kWh/PE, ranging from 16 to 71 kWh/PE [7]

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Conclusion