Decreasing dietary nitrogen consumption improves wastewater treatment efficiency and carbon footprint

Abstract

This article aimed to connect protein consumption with the nitrogen load to wastewater treatment plants (WWTPs) in Finland. The influence of the changes in nitrogen consumption on the WWTP environmental footprint was estimated using process simulation. As the main result, a connection was found between nitrogen loads from food consumption and the incoming load to a WWTP. This was done by analysing protein consumption data from the Food and Agriculture Organization of the United Nations (FAO) and incoming nitrogen load data from the Finnish environmental institute, SYKE. The impact of nitrogen consumption was estimated using different diet scenarios. Decreasing dietary nitrogen consumption by 16–24% could decrease nitrous oxide emissions by 16–24% and aeration energy (AE) consumption by 6–11%. An increase in dietary nitrogen consumption of 6–42% could increase AE consumption by 2–14% when effluent requirements were met. When considering the environmental impact of this increased aeration, it corresponds to an increase of 2–16%. Furthermore, nitrous oxide emissions could rise by 6–42% This information can be valuable to WWTPs and even consumers for influencing incoming nitrogen loads. HIGHLIGHTS Dietary choices affect the nitrogen load to the wastewater treatment.; Protein consumption and nitrogen load to the wastewater treatment have a strong correlation.; Recommended diets would decrease the environmental impact of wastewaters.; Nitrogen load strongly influences the climate impact of wastewater treatment.;

Keywords

• dietary nitrogen consumption
• environmental impacts
• greenhouse gas emissions
• nitrogen load to water bodies
• nitrogen removal
• wastewater treatment