Fit for 55: Research into nitrous oxide and methane emissions from WWTP’s

Dutch Water Authorities is carrying out intensive research at waste water treatment plants (WWTP’s) into the emission of greenhouse gases, such as nitrous oxide and methane. One of the topics is how the emissions of these greenhouse gases from WWTP’s can be reduced. With this research Dutch Water Authorities is replying to the European Commission’s plans to speed up the CO2 emission reduction.

Wednesday 14 July the European Commission presented new proposals to reduce more CO2 more quickly under the name ‘Fit for 55’. The plans stipulate that European CO2 emissions must be reduced by 55% rather than 40% by 2030. These plans represent a tightening of the 49% CO2 reduction target which was included in the Dutch Climate Agreement in 2019. Dutch Water Authorities states: “The water authorities are in favour of an ambitious national climate policy and it is clear that our WWTP’s face a tough challenge”.

Opportunities for more action

Dutch Water Authorities emphasises that the scope for action to reduce nitrous oxide and methane emissions is still relatively limited at present. “For methane, there are more possibilities than for nitrous oxide. Fortunately, we are gradually gaining more insight into the process control of nitrogen removal for nitrous oxide. We are leading the way in Europe in this respect. However, complete removal of nitrous oxide is not feasible.”

To measure is to know

According to the Intergovernmental Panel on Climate Change (IPCC), an average sewage treatment plant releases 700 kilotons of CO2 equivalents in nitrous oxide annually. Dutch Water Authorities: “That amount seems exaggerated and could be a factor 2 lower on average. The IPCC figures are based on international measurements at a limited number of treatment plants during a short period. This protocol is not easily applicable to the Dutch situation. That is why we are now measuring to the full how much nitrous oxide and methane is actually released at the treatment plants. Also we are investigating what we can do to reduce the emissions with control techniques.

Towards climate-neutral and circular purification

Dutch Water Authorities does not rule out the possibility that a new type of treatment will emerge in the future based on the ongoing research. The Water Factory concept is an example. “But the lifespan of existing wastewater treatment plants is more than thirty years. Because you can’t adapt the treatment plants immediately, you have to take other measures first. It would be great if we could capture CO2 and supply it to the horticultural sector or the process industry.”