UKWIR has published a new report ‘The greenhouse gas emissions of nature-based solutions for wastewater treatment’.

Abstract:

Using a systematic global literature review, factors were collated that increased or decreased emissions from methane, nitrous oxide and carbon from various typologies of constructed wetland, enhanced septic tank-nature-based solutions (NBS) and stabilisation ponds.  Responses were gathered from water companies, NBS installers and regulators specific to the UK and Irish context, on their interest and monitoring of greenhouse gases (GHGs) in these systems. Most research on this topic has been undertaken in Asia with few published findings for the UK. Most studies compared the GHG emissions from different types of constructed wetland, rather than comparing them to a conventional wastewater treatment plant. No factor was consistent across the three GHGs; what caused a decrease in methane often caused an increase in nitrous oxide, and vice versa. There is a need for long-term monitoring over the lifespans of nature-based wastewater treatment systems combined with consideration of the system’s operation, maintenance and plant-life.