Bringing European harmony to wastewater treatment

A new European standard comes into force from July 2008 which will harmonise individual countries' testing for small wastewater treatment systems. Alison Anderson, a member of the team that developed the new standard, explains why it will bring clarity to the industry.

The absence of clear performance guidelines for small wastewater treatment systems, which achieve their results in different ways and use a wide variety of biological processes, has always made product comparison difficult.

It has also made it awkward for manufacturers to trade across Europe, since they have been required to test their products to different standards for different countries.

However, a new European standard – EN12566 Part 3: Small Wastewater Treatment Systems – is being introduced to bring much-needed conformity to the industry and to make it easier for purchasers to compare the quality and effectiveness of different products.

The standard covers up to 50 population equivalents package or site-assembled domestic WwTWs. It defines the minimum requirements for these products and requires manufacturers to submit them for rigorous tests.

The key results of the tests will be clearly stated on the CE (Communauté Européenne) marking label, which allows approved manufacturers to trade across the European Union.

The minimum product requirements outlined by the new standard include the fact that the equipment must be watertight and corrosion resistant, and fitted with an alarm to indicate operational failure. It must also be designed to allow easy access for routine maintenance, sampling and sludge removal.

Plants may be constructed from concrete, steel, PVC-U, polythene (PE), polypropylene (PP) and glass reinforced polyester (GRP). The standard lays down the individual requirements for each type of material.

The standard also states that the hydraulic design of the plant, internal pipework and connections must ensure no back-flows, blockage or surcharging occur during normal operation.

Depending on the end use, factors given by national regulations, or codes of practice valid in the country of use, will determine the loads for which the plants are designed.

The performance tests are being conducted over a 38-week period by independent researchers in Germany, Belgium and Finland.

All plants must be assessed against the following core parameters – total chemical oxygen demand (COD), biochemical oxygen demand (BOD), suspended solids (SS), power consumption, daily hydraulic flow and temperature.

Efficiency ratios

Manufacturers must provide details of the design parameters used to size each system. These are usually based on total population loading, minimum and maximum

daily organic load or hydraulic volume.

While treatment efficiency ratios for BOD and SS are mandatory, other treatment efficiencies may also be declared to provide added reassurance for purchasers. These may include levels of ammonia, phosphate, and sludge production, for instance.

Performance tests are mostly conducted under normal (ie nominal flow) usage

conditions, which include defined intermittent flows during a 24-hour period. The performance of the product in the event of a problem, such as power failure, underloading, or overloading, is also assessed.

Following the successful completion of the tests, the product’s key statistics,

including its daily hydraulic load, treatment efficiency and electrical consumption, will be clearly recorded in documentation.

Other tested performance indicators, such as the nitrogen parameters and total phosphorus, may also be included. In addition, the manufacturer’s name and address will also be clearly identified, and a label indicating the product’s test status may be supplied.

Other significant information highlighted in the test report includes how much maintenance was required during the testing, how easy it was to access the components and how much power was required to operate the unit.

The standard has been prepared by the Technical Committee CEN/TC 165 “Wastewater Engineering” under a mandate provided by the European Commission and the European Free Trade Association (EFTA), and supports key EU directives.

Klargester, the sewage solutions provider, completed the testing in June 2005, with its BioDisc WwTW passing with flying colours. The company believes that it is the first manufacturer in the UK to complete the performance testing.

Manufacturers now have a transition period in which to carry out the performance and other specified tests enabling them to ensure that their products comply with the standard’s requirements. The normal 12-month transition period has been extended to allow for the lengthy performance test and expires in July 2008.

Manufacturers who do not test their products to the standard will not be able to export them for use in other European Union countries, unless they can prove to regulators by some other means that their goods will perform and are of a sufficiently high quality.

It is understood that the UK environmental regulators will recommend the installation of CE-marked products.

Alison Anderson is process manager for Klargester.

T: 01371 850537.

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