IVL Swedish Environmental Research Institute

I denna studie undersöks effekter av ett avgiftssystem för utsläpp av kväve och fosfor från avloppsreningsverk som bygger på samma principer som det svenska NOx-systemet för förbränningsanläggningar, vilket innebär att en avgift tas ut per kg utsläppt fosfor och kväve. Pengar betalas sedan tillbaka till avloppsreningsverken utifrån en återföringsnyckel.Avgiftssystemet utvärderades i Mälarens och Mörrumsåns avrinningsområden, samt vid utvalda avloppsreningsverk. Studien baseras till största delen på kontakter med ett 20-tal kommunala avloppsreningsverk där frågor om verkens teknik och aktuella data diskuterades. Ett syfte har varit att teoretiskt jämföra effekten av avgiftssystemet vid olika avgiftsnivåer med Baltic Sea Action Plan-betinget för Sveriges havsbassänger genom att skala upp resultaten inom Norra Östersjöns vattendistrikt. Resultaten i studien talar för att en avgift på 200 kr/kg kväve med bred marginal skulle uppfylla BSAP-målet att minska belastningen på havet med 3 000 ton årligen. Kostnaden för detta skulle emellertid bli likartad ett system med generella reningskrav och denna avgiftsnivå skulle innebära stora investeringar för många reningsverk. Vid en avgift på 75 kr/kg N skulle en kvävereduktion på ca 2 100 ton kväve/år kunna nås — dvs. ca 70 % av målet. I kombination med omprövningar av tillstånd som ändå kommer att ske för vissa reningsverk, för att klara vattenförvaltningens krav på god ekologisk status i recipienterna, är sannolikt  ett system med en avgift på 75 kg/kg N  ett  kostnadseffektivt sätt att uppnå såväl BSAP som övriga miljömål. För fosfor är det troligt att man redan idag utan ytterligare åtgärder kommer att klara det uppsatta målet att minska utsläppen med minst 15 ton/år.

The objective of this study was to investigate effects of a refunded emission payment system for nitrogen and phosphorus applied in municipal wastewater treatment plants. The system has been suggested by The Swedish Water & Wastewater Association and is inspired by the Swedish NOx abatement system for combustion plants where taxes are fully refunded to the polluting firms in proportion to market shares. In the investigated system for nutrients, the refunding is based on the number of persons connected to each plant. The exact refunding scheme was one of the key challenges in the project with new insights provided by discussions with potential participants. The emission payment system was evaluated in two catchments with different characteristics; the relatively dense populated catchment of Lake Mälaren and the more sparsely populated catchment area of River Mörrumsån, plus a small number of selected water treatment plants. One intention was also to theoretically compare the effect of the emission payment system with the Swedish commitment according to the Baltic Sea Action Plan (BSAP), by scaling up the results within the administrative region of Northern Baltic Proper including plants > 2 000 pe. The project also investigated how retention, i.e. reduction of the amount of nitrogen and phosphorus between the source and the sea, may affect the design of the system.  The study was largely based on contacts with around 20 municipal wastewater treatment plants, where issues about treatment technology and monitoring data were discussed. Questions regarding possible new technologies and costs of construction and operation were superficially investigated for some plants and more in depth for other plants. In this way cost-effective measures at the plants at certain payment levels were identified. The estimated reduction of nitrogen and phosphorus in an applied emission payment system were further used to scale up the results to national estimates for the Kattegat and the Baltic Proper for comparison with environmental goals and specifically with the Swedish commitment within the BSAP. An emission payment system is more likely to come into existence for nitrogen, and it was found that payment level of 200 SEK/kg N would obtain the target to reduce the annual nitrogen load to the sea by 3 000 tonnes per year (compared with 2006) with a broad margin. This reduction corresponds to the requirements on the Swedish wastewater treatment plants before 2021 related to the BSAP signed by the Swedish government. The cost for this reduction would however be similar to a system with general requirements (for all plants), and it would involve large investments for many plants. With a payment level of 75 SEK/kg N, a nitrogen reduction by 2 100 tonnes could be obtained — i.e. 70% of the target. Combining a 75 SEK/kg N payment level with renegotiations of existing regulations for selected wastewater treatment plants necessary to achieve good ecological status according to the Water Framework Directive (WFD) may be a more cost-efficient way to achieve BSAP as well as other environmental goals. For phosphorus it is likely that the established goal to reduce annual emissions by at least 15 tonnes (compared with 2006) will be achieved without further measures. For this reason, further reductions will likely be motivated by local requirements according to the WFD. With a general emission payment system a cost of around 3 000 SEK/kg P would be required to achieve significant emission reductions according to this study. There are probably advantages with an emission payment system compared with permit regulations, both regarding costs and performance. Importantly, administrative costs seem to be lower on a societal level. At the below mentioned workshop several participants question if it would even be possible to renegotiate all relevant existing permit regulations within the time frame of BSAP. In contrast, an emission payment system could be applied shortly and rapidly deliver process optimization and better use of the existing capacity in treatment plants. In addition, it is likely that the acceptance for such a system would be greater among participants than for general regulation of emissions by new requirements or renegotiations of existing permits, which is a non-trivial factor for reaching the goal. In a workshop concerning economic policy instruments arranged by IVL together with the Swedish Environmental Protection Agency and The Swedish Water & Wastewater Association in connection with this project, a principle was discussed in which an emission payment system could be designed so that the participating treatment plants may claim quantifiable measures in the recipients such as nitrogen and phosphorus uptake by cultivating mussels or tunicates.