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Water industry joins forces in global call for investment to tackle process emissions  

Water industry trade bodies around the world have joined forces in a call for investment to tackle the emissions associated with processing wastewater. 

Process emissions occur when wastewater is treated before returning it to the environment, producing several by-products including the potent greenhouse gases nitrous oxide, biomethane and carbon dioxide.  

Water UK, EurEau, the US Water Alliance, the Water Services Association of Australia, and Water New Zealand call for Governments and the global water industry to commit to working together to tackle process emissions, which constitute around half of the water sector’s total emissions.   

By working together, Governments can help to secure long-term funding to enable water companies to go further and faster in reducing processing emissions.   

Supporting the call to action are: 

The group is also committed to establishing: 

  • a research directory to help accelerate the sector’s global efforts to reduce nitrous oxide and methane emissions;
  • a global forum to share research conclusions and collaborate on future activity to expedite the reduction of greenhouse gas emissions. 

Christine McGourty, CEO of Water UK, said: “The water sector cannot play its full part in net zero without the reduction of emissions from processing wastewater. Governments around the world need to concentrate their efforts on one of the great challenges of our time, emulating the success of wind power, enabling a step change of technology at systems-scale.   

“Developing and investing in the best solutions will also unlock new materials for the circular economy, and help others decarbonise.” 

Mami Hara, CEO of the US Water Alliance, said: In addressing the climate crisis, we all win or we all lose. As the global water community accelerates climate mitigation efforts, we must continue to come together to share critical information and innovative strategies on how best to do so.

“In 2021, we launched a national Imagination Team with 36 diverse representatives creating a shared vision and pathway for greenhouse gas reductions across the US water sector. It is so exciting seeing water stakeholders step up to be part of the climate solution. Process emissions remain a significant challenge, and we’re proud to collaborate across the globe on this important area and ensure a more equitable, sustainable future for all.” 

Adam Lovell, Executive Director of the Water Services Association of Australia, said: “We know that fugitive emissions from wastewater processing is one of the significant challenges ahead – if we can all work together and play our part, we can meet this challenge, with typical water industry perseverance and innovation.” 

Lesley Smith, Insights and Sustainability Advisor, Water New Zealand said: “Wastewater process emissions can be a large proportion of emissions controlled by public sector organisations, many of whom have set ambitious climate reduction targets. The drivers are in place. What is missing is the science. With a better understanding of these emissions sources, this is an area we can make real gains in emissions reduction.  

“Ultimately, we need to transition from a wastewater to resource recovery mindset. The shift has the potential to transform our wastewater assets from net greenhouse gas producers to carbon sinks, enabling a range of broader environmental gains.” 

Oliver Loebel, Secretary General, EurEau, said:The European water sector is making significant efforts to reduce its emissions footprint. Nitrous oxide (N2O) - one of the by-products of wastewater treatment - for example, has a greater global warming potential than methane (CH4) and carbon dioxide (CO2). We need to identify the mitigation measures that we can implement which will have the most impact, and prioritise these. 

“Our government leaders should need to focus on climate neutrality and not only on energy neutrality. By doing so, a balance is needed between energy efficiency and renewable energy generation on the one hand and reducing N2O and methane emissions on the other. This is crucial to ensure that the benefits of energy efficiency are not reduced by large-scale emissions of N2O and methane from i.e. energy recovery.  

“We need committed investment in infrastructure and innovation to realise our zero GHG emission goal and potential contribution our sector can make to a sustainable, affordable future for us all.” 

Carl-Emil Larsen, CEO of DANVA, Danish Water and Wastewater Association, said: The Danish Ministry of Environment and the Danish water companies have jointly stated a goal for an energy- and climate neutral water sector in 2030.  

“Furthermore, there is a political agreement from the Danish Parliament, that all wastewater treatment plants (WWTP) above 30.000 PE must reduce their N2O emission with 50 % starting from 2025. A new report about CHemission from biogas plants situated on the WWTP shows, that the emission is five times higher than earlier expected. Therefore is it very important for us as well as the global water sector, that we get new tools and technology for reducing our GHG-emissions.

Steve Kaye, CEO of UK Water Industry Research, said:Our recent research has shown that it is not easy to remedy this situation based on existing research. There are wide ranges in emission estimates, and very few field-based studies on which to base any revised emissions factors. We need to address this global knowledge gap by generating robust emission data for individual wastewater treatment processes to enable appropriate control measures to be identified.”  

Maria Manidaki, Global Technical Lead for Net Zero at Mott MacDonald and co-author of the Water UK 2030 Net Zero Routemap, said: “Process emissions from wastewater operations, mainly methane and nitrous oxide, are one of the sector’s biggest decarbonisation challenges around the world. Exploiting novel treatment technologies, digital tools and improving operational responses will have a role in cutting these. However, to make informed investment decisions we first need to understand the source of these emissions, their magnitude and seasonal characteristics before we can adequately mitigate them. Immediate investment in mass monitoring systems would help the water sector unlock the necessary science and accelerate efforts to a net zero transition in the most cost-effective way.” 

Amanda Lake, Head of Process, Water Europe, Jacobs, said: “Process emissions are the largest source of carbon emissions from the urban water cycle as we decarbonise electricity. If we focus on asset health and process optimisation, and trial innovative modelling and circular economy treatment processes, we will find we have practical solutions to monitor and mitigate methane and nitrous oxide today. There is much to learn from around the world. It is exciting – and necessary – and we must do it together, now.” 

Ellen van Voorthuizen, Lead Consultant Greenhouse Gas Emissions of Royal HaskoningDHV said: “The water sector does play a vital role in the daily life of many people as they are responsible for water and wastewater services. To full fill this responsibility in the future, the sector wants to step up and reach Net Zero Carbon in 2030.” 

Patrick Decker, President and CEO of Xylem said: “We believe technology solutions and partnerships will be key to address the climate change mitigation and adaptation challenges the water sector faces. As a trusted global water technology provider we look to partner with utilities and the users of water and others to ensure we are advancing the most innovative technologies and effectively reduce emissions associated with processing wastewater. Together, the water sector will serve as an example of accelerated and effective transition to net zero.”

Jose Porro, CEO of Cobalt Water Global, said: “We have the knowledge and tools to start addressing water sector process emissions today, so it is now our responsibility to immediately start taking action.” 

Mikkel Holmen Andersen, Chief Technology Officer of Unisense, said:Today, nitrous oxide process emissions from wastewater treatment are by far the biggest scope 1 water sector challenge. There is massive talent and engineering power in the water sector but to tackle the problem, we need governments to provide funds and incentives to decouple ‘return of investment’ from process emission mitigation technologies unless we induce regulations and carbon taxes on process emissions.”

Further information:

US Water Alliance 

The US Water Alliance is a national organization advancing policies and programs that build a sustainable and equitable water future for all. Our network of over 150 members is transforming the way our nation views, values, and manages water. 

Our Climate Action Through One Water Initiative unites diverse interests in the water sector, including utilities, consulting firms, local government agencies, environmental organizations, community partners, and social practice artists, to address the climate crisis and foster equitable solutions through adaptation, resilience, and mitigation strategies.   

As part of this initiative, the Alliance is leading a sector-wide team in an Imagination Challenge to set goals for climate mitigation through water and identify strategic paths to get there, including how to address process emissions. A second phase of this work will kick off in 2022 working with water and wastewater utilities in the US to implement these strategies.   

Water New Zealand 

Water New Zealand has been working to support wastewater service providers to determine their greenhouse gas emissions. To this end we have developed guidance on determining wastewater emissions and begun benchmarking greenhouse gas emissions from wastewater.  

The guide is available to be purchased at this link: Carbon Accounting Guidelines for Wastewater Treatment: CH4 and N2O 

A link to a free webinar outlining content of the guide and subsequent questions flowing from their development is available here:  

The guidelines have been developed our Climate Change Group, a network or New Zealand water professionals who have formed to ensure the New Zealand water sector plays its part in adapting and limiting the worst impacts of climate change. We are now developing researcher partnerships to further knowledge gaps identified in our guideline, and welcome further collaboration with the international community to this end. 


EurEau is the voice of Europe’s water sector. We represent drinking water and waste water operators from 29 countries in Europe, from both the private and the public sectors.  

Our members are 34 national associations of water services. At EurEau, we bring national water professionals together to agree European water sector positions regarding the management of water quality, resource efficiency and access to water for Europe’s citizens and businesses. The EurEau secretariat is based in Brussels.  

With a direct employment of around 476,000 people, the European water sector makes a significant contribution to the European economy. 

UK Water Industry Research (UKWIR) 

UKWIR has been working on several UK based projects on process emissions. The latest is on quantifying and reducing direct greenhouse gas emissions from wastewater treatment processes in the UK and Ireland. This will help address the knowledge gaps in actual emissions from wastewater treatment processes used in the UK and Ireland and identify potential measurement, reporting and control measures. Essentially it will be a `proof of concept’ trial that can be widened to further validate a new approach for water and wastewater companies to adopt. 

Professor Jason Ren, Paul Busch Award Winner on Water GHG emission Research, Princeton University 

Dr Z. Jason Ren is the winner of the 2021 Paul L. Busch Award from the Water Research Foundation (WRF). With the $100,000 research prize, Dr. Ren will develop an inventory and digital tools to easily measure and track greenhouse gas emissions from the wastewater sector. A video explaining his award can be found here:  

Dr Ren is a Professor in the Department of Civil and Environmental Engineering and the Andlinger Center for Energy and the Environment at Princeton University in New Jersey. He is a leading expert on the water-energy nexus and has received notable recognitions, including the 2020 Walter L. Huber Civil Engineering Research Prize from the American Society of Civil Engineers for “producing groundbreaking technological advancements that are transforming water infrastructure for energy and resource recovery.”   

Dr Ren’s proposed research articulates an actionable approach to modernize wastewater treatment toward decarbonization and digitization. He understands the critical needs of the water and wastewater sectors in developing greenhouse gas (GHG) emission monitoring and mitigation programs, considering the sector’s commitment to energy efficiency and GHG emission reductions. Dr Ren plans to leverage state-of-the-art sensing technologies to measure emissions from specific sites, and then use machine learning (ML) tools to derive industry trends from the new data. Dr Ren was selected because of his novel, data-driven approach to quantifying emissions, and the tools and web applications he plans to create to make that data usable by water utilities looking to manage the emissions from their facilities. 

Mott MacDonald 

Mott MacDonald is a US$2bn engineering, management and development consultancy whose purpose is to improve society by considering social outcomes in everything they do; relentlessly focusing on excellence and digital innovation, transforming our clients' businesses, our communities and employee opportunities. Responding to climate change is embedded in its work, core to its operations and projects. The consultancy looks at everything through a climate lens, and seeks out new and more effective solutions to the climate challenge. 

Its strong global water team works closely with clients across the water sector value chain shape and implement their decarbonisation plans. Mott MacDonald’s work on process emissions ranges from supporting the development of the New Zealand wastewater emissions guidelines to its involvement in developing the Water UK 2030 Net Zero Routemap and supports individual water utilities with their decarbonisation plans.  

In the absence of monitoring information, Mott MacDonald is helping clients assess the range of process emissions and delivering solutions to manage those through the use of digital tools and novel wastewater treatment technologies. The consultancy has a long track record in implementing solutions for effective biosolids management and resource recovery and has also been working closely with supply chain partners to explore more agile ways for monitoring process emissions in wastewater treatment. 


At Jacobs, we’re challenging today to reinvent tomorrow by solving the world’s most critical problems for thriving cities and resilient environments. With decades of experience delivering innovation in wastewater treatment, we are delivering the UKWIR research on process emissions as well as collaborative monitoring and mitigation work with partners across the world - creating a zero carbon, circular economy water sector for all. Process emissions insights: 

Royal HaskoningDHV 

Royal HaskoningDHV has been involved in the research on greenhouse gas emissions from wastewater treatment plants since 2008 in the Netherlands. Based on these research activities we see opportunities to reduce the emission of methane and nitrous oxide straight away via: 

  • Capturing the emitted methane from sludge storage tanks after sludge digestion and valorize the methane in a sustainable energy source. 
  • A robust design and operation of the wastewater treatment plant to avoid high levels of nitrous oxide emission and in the meantime sustain or even improve the effluent quality. 

Cobalt Water Global 

Cobalt Water Global is providing AI and machine learning platform to mitigate N2O emissions from wastewater treatment works. Implementing their approach, they have reduced up to 70 percent of the total process emissions from just making smart process adjustments.  They have launched the We Can Stop N2O Emissions Challenge with an interim goal of reducing 25k tons of CO2e by next Climate Week NYC and are giving free access to their platform for the first five to join the challenge by the end of COP26. 


Unisense leads the development and proof-of-concept of the world’s only dissolved nitrous oxide sensor for wastewater monitoring and GHG emission control. Working extensively with equipment for environmental monitoring for wastewater real-time N2O mitigation controllers and modelling focused on the sensor technology, including novel aeration, COD, and deammonification controls enabling net-zero emission from wastewater treatment.