CE Marking and declaration of conformity for constructed wetlands for up to 50 PT built in series exemplary explained with the initial type test of the treatment efficiency performance

In order to ensure free movement of goods within the European Economic Area and the European Community, the EC Treaty (Treaty of Rome) requires manufacturers to declare the conformity of their products with the EC Directives and Regulations applicable to their product. Manufacturers confirm this with the CE marking on their products. A product may only be CE marked and placed on the market or used if it complies with all EU directives applicable to the product.

Constructed wetlands are used for the decentralized treatment of domestic wastewater and, with the appropriate size, fulfil the same function as other small wastewater treatment plants. Thus, a constructed wetland is a special form of the wastewater treatment plant.

This paper will discuss how the proof of conformity can be provided according to the construction products regulation (CPR) for constructed wetlands and, thus, fulfil one of the most important requirements for CE marking (NN, 2011).

Commonly called the CPR, the regulation (EU) no. 305/2011 of the European Parliament and of the Council of 9 March 2011 laid down harmonized conditions for the marketing of construction products (NN, 2011). This regulation is one of the ‘New Approach’ directives of the European Union, which are intended to ensure the free movement of goods. As part of the conformity assessment procedure, the CPR is the most important specification to be applied to this product – constructed wetlands – under the relevant directives and regulations. The Low Voltage Directive (2006/95/EC), the Directive on Electromagnetic Compatibility (89/336/EEC) and the Machinery Directive (98/37/EC) should be named here as examples of further guidelines that can be applied with regard to conformity but shall not be respected in further detail.

According to Article 2, Paragraph 1 and 3 in accordance with the CPR, a ‘construction product’ is to be understood as any product that is produced for incorporation in a permanent structure of building construction as well as in civil engineering work. Like small wastewater treatment systems, constructed wetlands are used in civil engineering and are connected via the line of the influent to the building construction. Therefore, they are to be regarded as a construction product.

An essential requirement of the CPR stipulates that construction products may only be placed on the market if they are suitable for their intended use. Construction products have to meet the following essential requirements according to Annex I of the CPR:

1. Mechanical resistance and stability

2. Safety in case of fire

3. Hygiene, health and the environment

4. Safety and accessibility in use

5. Protection against noise

6. Energy economy and heat retention

7. Sustainable use of natural resources

A product is assumed to be fit for use in Europe, if it is conform to a harmonized standard or a European technical approval.

Three standards of the European standard series EN 12566 ‘Small wastewater treatment systems for up to 50 PT’ are especially decisive for constructed wetlands.

Since November 2014 CE-marking requirements apply to certain types of wetlands, soil filters and other treatment systems in flexible sheets. Two parts of the particularly relevant European standard EN 12566 ‘Small wastewater treatment systems for up to 50 PT’ are decisive for flexible sheet systems. The scope of both parts of the European harmonized standard EN 12566-6: 2013, as well part 12566-3: 2005 + A2: 2013, which were published in November 2013 respectively August 2014 in a revised version, now include small wastewater treatment plants, constructed in containers of flexible sheets. Also affected by this extension of the scope is standard EN 12566-7:2013, harmonized also in August 2014.

For CE marking initial type tests are required by the EN 12566 standards for treatment efficiency performance, structural behavior, water tightness, durability, release of dangerous substances and fire resistance and have to be executed by an accredited testing laboratory a so called ‘notified body’ as shown in Table 1.

In the following, the treatment efficiency test will be explained in more detail.

The results of the testing are documented in a report, which serves the manufacturer to declare the treatment efficiency of his constructed wetland as part of the declaration of performance as basis for the declaration of conformity of the product to harmonized European construction regulations. The results of the treatment efficiency testing are expressed in treatment efficiency ratios expressed in %. There is no pass or fail as an outcome. The standard does not give any limits. There are also the effluents characteristics documented as result of the testing, which can be used for national approvals under the aspect of water law.

For prefabricated parts of the plant, the manufacturer has to perform a factory production control including documentation to ensure that products placed on the market comply with the declared performance. This production and quality control involves comprehensive aspects of production, such as calibration or inspection and maintenance of all equipment used in the manufacturing process, documentation of all raw materials and components and documentation of the design process. In addition, each plant must be identifiable and traceable regarding their production and the individual system must carry a clear identification.

This explanation applies to small sewage treatment plants built in series. The CPR allows exceptions to the obligation to draw up a declaration of performance. If plants were individually manufactured or custom-made in a non-series process in response to a specific order, and installed in a single identified construction work, by a manufacturer who is responsible for the safe incorporation of the product into the construction works, a manufacturer may refrain from drawing up a declaration of performance when placing a construction product covered by a harmonized standard on the market the method of initial type testing can be replaced by a ‘specific technical documentation, ’ with which the conformity of the product is detected with the applicable requirements.

However, in this case he must prove that the procedures used are equivalent to the conditions laid down in the harmonized standards process. The test methods of the standard are very special in particular for determining the treatment efficiency performance and demonstrating equivalence is very difficult. The bottom line is that for products corresponding to the scope of the EN 12566 standard series it is the easier way to draw up a declaration of performance.

For an explanation of the term ‘built in series’ in relation to small wastewater treatment plants, the German authors Sieder/Zeitler/Dahme/Knopp (2016) deliver following explanation in their publication ‘Wasserhaushaltsgesetz und Abwasserabgabengesetz’ (‘Water Act and Wastewater Charges Act’): ‘For the production in series not the existing number is significant, but the manufacturer's intention to manufacture additional copies of this design in the future (…) site assembled production does not prevent a production in series’. In November 2015 the member states met to find a more detailed definition of the term ‘built in series’, but could not come to an agreement so far.

Currently not many European manufacturers of constructed wetlands built in series are aware, that they have to CE-mark their product. But this regulation also gives the manufacturer the chance to trade their product more easily anywhere on the European market. If it was proven with an initial type test that the system is fit for use no additional national demands concerning the design need to be respected, as the judgement of the European Court C-100/13 against Germany shows. The manufacturers can build their systems according to their practical experience and their expertise and demonstrate the ability of the product to function in an initial type test. Provided that the results show that they comply with the different national requirements for the effluent requirements, the installation, operation and maintenance, they can also be operated. The latter criteria are not part of the European standards of the standard series EN 12566 since these are standards under the CPR and it includes only statements on the design and execution of the construction product.

Constructed wetlands are construction products and if they are designed for up to 50 PT and built in series the standards of the EN 12566 need to be respected and the product CE-marked. This regulation also gives the manufacturer the chance to trade their product more easily anywhere on the European market and no additional national demands concerning the design need to be respected. This gives manufacturers the freedom to build their systems according to their practical experience and their expertise. The results of the initial type testing can additionally be the basis for applying for national approvals under the aspect of water law.