Position Paper on EU's Urban Wastewater Treatment Directive | Aquatech
Wastewater Sludge Europe

EU Urban Wastewater Treatment Directive: experts call for facility-level monitoring

Sunday, 26 March 2023

Addressing nitrous oxide emissions

The EU has recently published a draft revision of its established regulations to guide the management of wastewater and align it with its energy and circular economy strategies. 

A coalition of technology and application experts has come together to produce a position paper on the European Union’s (EU) Urban Wastewater Treatment Directive (UWWTD).

AM-Team, Bentley, Cobalt Water Global, Jacobs, Ragn-Sells, Royal HaskoningDHV, Suez, Unisense, Variolytics, Veolia and Xylem have developed a paper calling for the monitoring of process gas emissions in wastewater treatment plants to be included in the proposed revision.

“As technology and application experts, we welcome the latest ambitious proposal for a revised UWWTD, however, we now feel there is a need to specifically address the monitoring and mitigation of process gas emissions and suggest important amendments to the UWWTD proposal to address this,” the report said.

Addressing nitrous oxide emissions

The coalition’s key concern is that the UWWTD fails to address the mitigation of nitrous oxide emissions, which represent a global warming potential 273 times higher than that of carbon dioxide. 

Emissions of process gases such as nitrous oxide (N2O) and methane (CH4), from wastewater and sludge treatment, make up 60-70 per cent of the greenhouse gas emissions from wastewater treatment plants, making them the leading contributor to the overall environmental footprint of wastewater operations.

A previous whitepaper covered on Aquatech Online examined nitrous oxide from wastewater treatment.

The coalition would like to see facility-level monitoring to gather evidence on nitrous oxide generation and release and the specific emission factors. This is to support accurate greenhouse gas accounting and to support mitigation. 

“To reduce the potent greenhouse gas emissions from wastewater treatment, we recommend Member States be required to monitor the emissions of all process gas, including nitrous oxide, produced by the operational activities of the water utilities, in addition to the energy used and produced by urban wastewater treatment plants of above 10 000 p.e,” the report states.  

Increased awareness of the impact of nitrous oxide and methane on global warming over the last decade has accelerated the technical development of monitoring and mitigation technologies in activated sludge treatment.

Online sensors, advances in biokinetics and flow mechanics, as well as modeling approaches, offer reliable and affordable solutions for monitoring real time emissions of nitrous oxide in wastewater treatment. 

Further treatment technologies

Beyond the application of demonstrated mitigation approaches, the coalition also states that there are significant opportunities to further develop treatment technologies, optimize the harvesting of resources, and prevent the generation of nitrous oxide. 

While they said this approach “remains very much untapped and requires an understanding of nitrous oxide emissions through site-level monitoring”, they believe that only with a requirement for nitrous oxide monitoring in the UWWTD proposal will Member States be able to support near-term mitigation and accelerate the technology development required for advanced wastewater treatment options.