Carbon footprints of Scandinavian wastewater treatment plants

Abstract

This study estimates the carbon footprints of 16 municipal wastewater treatment plants (WWTPs), all situated in Scandinavian countries, by using a simple model. The carbon footprint calculations were based on operational data, literature emission factors (efs) and measurements of greenhouse gas emissions at some of the studied WWTPs. No carbon neutral WWTPs were found. The carbon footprints ranged between 7 and 108 kg CO2e P.E.(-1) year(-1). Generally, the major positive contributors to the carbon footprint were direct emissions of nitrous oxide from wastewater treatment. Whether heat pumps for effluents have high coefficient of performance or not is extremely important for the carbon footprint. The choice of efs largely influenced the carbon footprint. Increased biogas production, efficient biogas usage, and decreased addition of external fossil carbon source for denitrification are important activities to decrease the carbon footprint of a WWTP.

Carbon Footprint Analyses of Mainstream Wastewater Treatment Technologies under Different Sludge Treatment Scenarios in China

“…On the other hand, under the big backdrop of global and national actions to achieve carbon neutrality or even carbon negative development, the Chinese wastewater treatment sector will inevitably need to follow the lead to reduce GHG emissions and cut energy consumption to mitigate its climate change impact. Carbon footprint accounting thus should be adopted as a tool to measure climate change impact in developing technology roadmaps for wastewater treatment and in the decision-making process for taking precautionary measures [10]. With the development of urbanization in China, more WWTPs will be constructed and operated in small and medium cities in the near future; therefore, plants with an average flow rate of 20,000 cubic meters per day (m 3 /day) will be the mainstream scale of newly built WWTPs.…”

“…The treatment and disposal of raw sludge with increasing production from wastewater treatment process not only brings about potential pollution to the environment, i.e., metals and trace pollutants contained might pollute underground water and soil, but also require energy and chemicals during the process. In previous studies on GHG accounting, most are focused on the GHG emissions from the liquor treatment [4,[10][11][12][13] or sludge treatment [14][15][16] separately; less attention has been paid to quantify GHG emissions to a larger extent, with the integration of both wastewater and sludge treatment in the system boundary. The measurement of GHG emissions including both the wastewater and sludge treatment process could shed light on the water-energy-GHG nexus relationship and contribute to the GHG mitigation efforts in WWTPs with synergy effects.…”

Review of Upflow Anaerobic Sludge Blanket Reactor Technology: Effect of Different Parameters and Developments for Domestic Wastewater Treatment

“…In the United States and other developed countries, methane generated from anaerobic digestion is combusted for energy production, at large treatment plants, and is at least flared and converted to CO 2 at smaller plants [47]. Increased biogas production, efficient biogas usage, and in turn decreased addition of external fossil will lead to reduction of carbon footprint of a wastewater treatment plant [48].…”

Comparative analysis of energy intensity and carbon emissions in wastewater treatment in USA, Germany, China and South Africa

“…Some WWTPs have even changed their whole perspective on ''waste" to ''input" from which energy, nutrients (N and P), and treated water can be produced with a substantial social value, shifting the operation from a cost to a profit center [4,[16][17][18][19][20][21][22][23][24][25]. In addition, WWTP designers and operators can make substantial contributions to the reduction of greenhouse gases (GHGs) through energy capture and process modifications [26,27].…”