Published on 9 November 2023
FAQs on phosphorus recycling
The amended Waste Ordinance no longer sets a deadline for phosphorus recovery. Once a phosphorus recovery plant is operational, it must run at full capacity until the required quota is met, i.e. until 16kg of phosphorus per tonne of sewage sludge dry matter has been recovered, or until phosphorus has been completely recovered from animal and bone meal. For sewage sludge, this quota corresponds to treating approximately 60% of sewage sludge in Switzerland. The rest can continue to be used as fuel.
However a new deadline has been set for the cantons to include phosphorus recovery in their waste or sewage sludge disposal plans. This means that by 1 January 2028 the cantons must decide whether sewage sludge will be delivered to a phosphorus recovery plant or may be used as fuel without recovery (Art. 51 para. 2 ADWO).
Switzerland relies heavily on phosphorus imports, especially to meet the need for phosphorus fertilisers in agriculture. Natural deposits of phosphorus-containing minerals are concentrated in a few countries (e.g., Morocco, China, Russia). Phosphorus fertilisers using phosphorus from primary deposits often contain undesirable concentrations of heavy metals (e.g., cadmium and uranium). Switzerland has strict limits for heavy metal concentrations in mineral fertilisers and can therefore only source phosphorus from a limited number of mines. For this reason, Switzerland has until now imported much of its mineral phosphorus fertiliser from mines in Russia. The war in Ukraine has again highlighted the issue of Switzerland's reliance on imports and the importance of an independent supply of phosphorus.
The processes are based on different principles and have different starting points. In decentralised processes, phosphorus is extracted directly from the wastewater and sewage sludge streams at wastewater treatment plants (WWTPs). Centralised processes currently treat the sewage sludge ash after incineration and can take place at other locations independently of the wastewater treatment plants. In recent years, the spectrum of sufficiently well-developed and feasible recovery processes has narrowed considerably and wet-chemical extraction or digestion using sewage sludge ash has become the preferred method. The advantages are a high recovery rate and compliance with the limits for heavy metals in phosphorus fertilisers. In Switzerland, there are currently projects in the pipeline for three processes: Phos4Life, REALphos and ZAB.
The cantons are responsible for the disposal of municipal waste and sewage sludge (Art. 31b para. 1 EPA). They are thus obliged to implement the requirements for phosphorus recovery, or to ensure they are implemented, in accordance with ADWO.
Various stakeholders will need to work together to implement the phosphorus recycling requirement. The SwissPhosphor platform was set up under the leadership of the FOEN to ensure coordination and the exchange of information. The platform brings together the FOEN, FOAG, the cantons, wastewater treatment plants and wastewater management associations, existing users of wastewater sludge, representatives of the fertiliser industry, agriculture and the scientific community.
The cost of the development, construction and operation of phosphorus recovery plants are expected to exceed the market revenue from the sale of the recycled phosphorus products. Depending on the process, the additional costs are likely to be in the range of CHF 5 per citizen per year. These costs will be covered by wastewater charges.
There will be two main products: phosphoric acid and phosphorus fertiliser. Phosphorus fertilisers are used in agriculture and horticulture. In Switzerland, industry association requirements for secondary source phosphorus fertilisers are stricter than the legal limits for fertilisers containing recycled phosphorus. However, compliance with these stricter limits should be feasible at the planned installations. High-quality technical phosphoric acid is used as a raw material in the chemicals/industrial sector.
The export of recycled phosphorus products is possible under the applicable Swiss environmental legislation. The circular economy does not mean products have to be used in the place they are produced. The main principle is to extend the lifecycle of a product for as long as possible, regardless of where it is used. For example, a phosphorus fertiliser made from recycled phosphorus may be exported to Spain to fertilise courgettes. The courgettes are then imported for consumption in Switzerland. Any foreign import of Swiss recycled phosphorus fertilisers would be subject to the rules in that country. Switzerland's limits are also important with regard to exports, however. A recycled phosphorus fertiliser is only considered a 'product' if it complies with the national minimum requirements for fertilisers (MinRec limits, ORRChem). Hence any fertiliser produced using sludge must meet the Swiss requirements even if it is intended for export, as it would otherwise have to be exported as 'waste' and not a 'product’. If the export was deemed to be 'waste', it would be subject to the requirements in Art. 15 ff. and Art. 17 Waste Movements Ordinance (OMW).
The legal requirements for mineral recycling fertilisers are listed in the Chemicals Risk Reduction Ordinance (ORRChem; SR 814.81) in Annex 2.6, Section 2.2.4. In the course of the total revision of the Fertiliser Ordinance (SR 916.171), the designation ‘mineral recycling fertilisers’ in ORRChem will be replaced by the component material categories, CMC12 and CMC 13, as of 1 January 2024. The existing limit values for mineral recycling fertilisers will be adopted and supplemented with some new EU limit values. The limit values for CMC 12 and CMC 13 will be found in ORRChem in Annex 2.6 under Section 2.2.2.2.