Everyone is talking about KARL. No, not the Karl from next door, nor KARL the Great, the famous Emperor Charlemagne of the Frankish Empire, nor the last Austrian Emperor Karl I, and certainly not 'Der Herr KARL' (which is actually a well-known Austrian theatre play), because the correct German term would be DIE KARL (female) - the German acronym for the European Union's Urban Waste Water Treatment Directive. The acronym in the English language is UWWTD. A bit boring, isn't it? KARL sounds much more charming, I guess. So, we're going to stick with KARL for now. Strictly speaking, it could also be called 'KARL the Second', as this is the revised version of the 1991 Directive, the 'mother' of modern wastewater treatment in Europe (Council Directive 91/271/EEC of 21 May 1991 concerning urban wastewater treatment).
After 30 years: Time for a revision of the Urban Waste Water Directive
In October 2022, 30 years after its entry into force, the EU Commission published a draft for a new version of the Directive with numerous amendments and new requirements. After intensive discussion of the draft by various stakeholders, both the European Parliament and the European Council submitted their amendments. In a trialogue with the Commission, the proposals were finally merged into a joint Parliament and Council text. The Parliament approved it on 10 April 2024 and the Council finally approved it on 5 November 2024 due to the elections in June. The Directive is therefore deemed to have been adopted and was published in the Official Journal of the European Union on 12 December 2024 as
Directive (EU) 2024/3019. It will enter into force two weeks after publication. Member States will then have 30 months (i.e. until July 2027) to transpose it into national law.
New version, but what is actually new about the Urban Waste Water Directive?
There are some significant changes compared to KARL I:
- For example, the obligation to construct urban waste water treatment plants will be extended to all agglomerations of at least 1000 inhabitants (the current limit is 2000 inhabitants).
- In addition, the requirements for nutrient elimination (i.e. removal of nitrogen and phosphorus) will be tightened.
- Integrated urban waste water management plans will be developed at local level to better control combined sewer overflows (urban waste water and storm water overflows). These are expected to increase as heavy rainfall events become more frequent due to climate change.
- In addition, urban waste water will be subjected to additional treatment (4th stage) to remove a wide range of micropollutants.
- A binding energy-neutrality target will be introduced at Member State level for the urban waste water treatment sector.
- New monitoring obligations will be introduced, including the monitoring of microplastics (including sewage sludge) and certain viruses such as SARS-CoV-2 in urban wastewater.
- Member States will be required to improve and maintain access to sanitation for all, in particular for vulnerable and disadvantaged people.
- New provisions on public information, access to justice and compensation are also included.
Read also: Wastewater treatment simply explained: the 4 purification stages
Support for the implementation of the recast of the Urban Waste Water Directive
There are at least three areas in which the
Donau Chemie Group can provide significant support to wastewater treatment plants.
New threshold limits for phosphorus and nitrogen (Article 7)
Gradual implementation of nutrient elimination by 2045
In the past, many wastewater treatment plants were not required to remove nutrients (tertiary treatment). Only those discharging into sensitive water bodies were obliged to do so. For example, plants with 100,000 p.e. or more had to comply with a limit of 1 mg/l phosphorus in the effluent. For smaller plants (10,000 p.e. and above), a limit of 2 mg/l was defined, unless more stringent requirements were laid down in national legislation. However, as large wastewater treatment plants in particular contribute significantly to eutrophication, all wastewater treatment plants with a population equivalent of 150,000 p.e. or more (even in non-sensitive areas) will have to remove nitrogen and phosphorus from their effluent.
In addition, all agglomerations of 10,000 p.e. or more will have to remove nutrients if they discharge their effluent into sensitive water bodies, some of which are defined in the Directive and others may be defined by Member States.
Phosphorus limits for large and small plants
The future limit values for phosphorus are 0.5 mg/l for large plants and 0.7 mg/l for smaller plants. Implementation will be phased in, with the first plants to comply by the end of 2033. By 31 December 2039, all wastewater treatment plants with a population equivalent of 150,000 or more must have implemented tertiary treatment, and by 31 December 2045, plants with a population equivalent of 10,000 or more in sensitive areas must have done so.
The fourth treatment step (Article 8)
So-called micropollutants, i.e. substances that can pose a risk to public health and the environment even at very low concentrations - a few micrograms per litre - will have to be removed as part of more advanced treatment.
Priority for large plants and sensitive waters
As with nutrient elimination, this obligation applies primarily to large plants (>150,000 p.e.) and also to plants with 10,000 p.e. or more that discharge into water bodies that are classified as sensitive with regard to micropollutants. These may be waters where the effluent from the treatment plant is a significant contributor to the water discharge (dilution ratio less than 10), or waters used for drinking water extraction, aquaculture or bathing. Member States must identify these sensitive areas by the end of 2030 and reassess them for the first time in 2033 and every six years thereafter.
Substances to be considered
The Directive also sets out a list of 12 substances in two categories to be considered for the fourth treatment step. The requirements of the Directive are considered to be met if at least six of these substances are removed from the influent load by an average of 80%. Twice as many substances from category 1 must be removed as from category 2. The list will be kept under review by the Commission and adapted as necessary. By 31 December 2033 at the latest, the first installations and by the end of 2045 all installations with more than 150,000 p.e. and all installations with more than 10,000 p.e. in sensitive areas must comply with the requirements of Article 8.
Financing via Extended Producer Responsibility
Under Extended Producer Responsibility, 80% of the costs of the 4
th treatment step (investment and operating costs) are to be borne by the producers of the micropollutants. This requires the establishment of an organisation in each member country to which the manufacturers pay their contributions. The UWWTD only lays down minimum requirements for these organisations, the establishment of which is the responsibility of the Member States.
Energy neutrality of wastewater treatment (Article 11)
Use of biogas, heat pumps and photovoltaic systems
Wastewater treatment plants both have high energy demands (especially for aeration in aerobic wastewater treatment) and a high potential for covering these demands themselves. Wastewater contains a lot of energy. For example, there are already wastewater treatment plants that use heat pumps to recover the thermal energy in the water. Biomass has long been converted into biogas in digesters and used in combined heat and power plants to generate heat and electricity. Sewage treatment plants often have large areas that could be used to install photovoltaic systems. For this reason, the Directive sets energy neutrality at national level as a target by the end of 2045. At national level because not all wastewater treatment plants have the same conditions for sufficient use of renewable energy. The Directive also allows renewable energy installations outside the treatment plant to be taken into account, provided they belong to the operator or owner of the treatment plant.
Carrying out energy audits
Energy audits must be carried out at least every four years. They should assess the potential for using renewable energy, identify energy savings and consider issues such as the use of excess thermal energy (e.g. for district heating). The first energy audits must be carried out by the end of 2028 for installations with more than 100,000 p.e. and by 31 December 2032 for installations with more than 10,000 p.e.
Urban Waste Water Directive: How can the Donau Chemie Group contribute?
Phosphate precipitation is the core competence of our
water technology products. Donau Chemie has more than 30 years of experience in the production and application of iron and aluminium based coagulants. They will continue to play an important role in the future due to stricter requirements for nutrient elimination. In this context, customers in the water industry can rely on competent support with products and know-how.
What if you could combine phosphorus and micropollutant removal in one product? Could that work?
Yes, it is possible. The patent-pending Donau PAC Aquaclear is, as far as we know, the first product on the market that can both precipitate phosphate and meet the requirements of the Directive on the elimination of micropollutants. As a long-term stable combination of activated carbon and coagulant, dosed as usual with a dosing pump,
Donau PAC Aquaclear is easy to use. The product is particularly suitable for systems that do not intend to make any structural changes. Larger systems may need to invest in their own systems, e.g. activated carbon filters. Here
Donau Carbon's expertise and products, including ready-made filters, can provide competent support.
And can the Donau Chemie Group also contribute to energy neutrality?
Quite clearly: Absolutely! The
production of biogas will be an important element. In order for biogas to be used in gas engines, it must meet certain quality criteria. For example, the content of sulphur compounds and certain silicon compounds (siloxanes) must be very low, otherwise the engine can be damaged. Suitable products (e.g.
Donau Bellamethan) can be used to fix sulphides in the sludge and prevent volatile sulphides (H
2S) from entering the gas phase. In addition, suitable activated carbons can be used to further reduce the sulphur content of the biogas, and the siloxanes can also be adsorbed on the activated carbon. In addition, systematic pre-precipitation allows more organic load to be introduced into the digestion process with the primary sludge. This increases biogas production and reduces the load on the aerobic step. This saves aeration energy and reduces direct greenhouse gas emissions in biological wastewater treatment, as shown in a
study by the
Swedish IVL Institute in cooperation with
INCOPA, the Association of European Coagulants Producers). In addition, the carbon footprint of coagulants is very small compared to other sources in wastewater treatment due to the use of secondary raw materials. Coagulants therefore make an important contribution to Europe's circular economy (see
Life Cycle Assessment (LCA) study on the production of coagulants).
Long-term support
As you can see, even after more than 30 years, there are always new issues in wastewater treatment. But one thing is certain - Donau Chemie Group and its products will continue to be relied on in the future - even if KARL III should come in 30 years' time.