Eutrophication of surface waters is a major environmental concern and poses risks to the European economy, the environmental and public health. One of the most polluting compounds of surface waters is nitrogen. Wastewater treatment facilities have to comply with the strict nitrogen discharge standards of the Water Framework Directive. Another major concern is climate change. The emission of greenhouse gasses (GHGs) should be reduced to mitigate climate change. Recent studies indicate that wastewater treatment facilities contribute to the uncontrolled release of methane into our atmosphere. The EU member states have committed to a climate and energy policy framework to be achieved by 2030. Considering its contribution to climate change, a focus on limiting methane emissions could contribute significantly to meet the 2015 Paris Agreement to limit global warming to a maximum of 2 degrees Celsius.
The aim of this project was to investigate the market potential of a novel wastewater treatment method that combines two microbial processes to remove nitrogen and dissolved methane from wastewater. The two key processes are anaerobic ammonium oxidation (anammox) and nitrate- or nitrite-dependent anaerobic methane oxidation (N-damo). A wastewater treatment system based on these two microbial processes tackles two major environmental concerns in one efficient system by decreasing the nitrogen discharge to surface waters and reducing the emission of the potent GHG methane.
A three-step approach was applied to assess the economic potential of simultaneous methane and ammonium removal in two business cases: a municipal wastewater treatment plant and an industrial wastewater treatment plant. In the first step, the daily performance of different treatment set-ups was calculated using a set of four parameters. These parameters were derived from the expected unique selling points (USPs) of the anammox/N-damo system: 1) higher nitrogen removal efficiency; 2) lower aeration costs; 3) lower sludge production; and 4) lower carbon footprint. To see the economic weight of each of the performance parameters in the annual benefits, the parameters were given a financial value (step 2). In the third step, the economic potential was explored by taking into account different price scenarios.
Both business cases show annual benefits in the performance of the anammox/N-damo treatment set-ups compared to the already applied anammox systems. The set-ups showed to be more energy-efficient in nitrogen removal and had a lower carbon footprint. The treatment set-ups in this project showed a potential reduction of GHG emissions of about 30 to 50 % compared to already applied anammox systems. Both case studies showed that there is an economic potential in a greenfield situation, however, there is no solid economic potential for a situation of retrofitting an existing anammox system.
At this moment there is no financial incentive to apply methane oxidation to reduce the carbon footprint of a wastewater treatment plant. Methane is not taken into account yet in the carbon trading system of the European Union (EU-ETS). However, there is a growing awareness about the actual contribution of methane to the global warming effect. This may lead to changes in the carbon trading system and to the number of greenhouse gasses to be monitored. A growing number of countries and regions have introduced a form of carbon pricing or taxing. The high carbon prices tested in this business case may become very realistic in the next ten to fifteen years.
The results of this Proof of Concept project makes a strong business case by showing the added value of a combined anammox/N-damo treatment process for an energy-efficient nitrogen removal and reduced carbon footprint. It adequately addresses both concerns of nitrogen pollution and GHG emissions and is therefore a ‘future-proof’ option worth exploring in further detail. One of the business case locations has shown interest and the industrial partner is considering to develop a pilot plant installation.
