NEW EU STANDARD WILL BRING CONFORMITY TO SMALL WASTEWATER TREATMENT SYSTEM INDUSTRY by Alison Anderson, process manager for leading sewage solutions provider Klargester, and member of the team which developed the new standard.

Small wastewater treatment systems achieve their results in different ways and use a wide variety of biological processes. However, the absence of any clear performance guidelines for these products has made it difficult for specifiers to compare them.

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

However, this situation is changing with the introduction of a new European standard - EN12566 Part 3: Small Wastewater Treatment Systems - which covers up to 50 population equivalents Package and/or Site Assembled Domestic Wastewater Treatment plants.

The standard will bring much-needed conformity to the industry by defining minimum requirements for these products. It also involves rigorous performance tests, which are being conducted over a 38-week period by independent researchers in Germany, Belgium and Finland.

The minimum requirements include the fact that the products must be structurally durable, watertight and corrosion resistant. They should also be fitted with an alarm to indicate an operational problem, such as electrical, mechanical, or hydraulic failure.

Plants may be constructed from concrete, steel, PVC-U, Polythene (PE), Polypropylene (PP) and Glass Reinforced Polyester (GRP), and 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.

During the performance tests, 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.

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

Performance tests are mostly conducted under "normal" (i.e. 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, and supports key EU directives.

Klargester completed the testing in June 2005, with its BioDisc sewage treatment plant 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.

To conclude, sewage treatment plants are effective, yet complex solutions for off-mains drainage properties. With so many different makes and models on the market, the new standard will bring much-needed clarity and conformity to the industry. It will make it easier for specifiers and their customers to understand exactly what they are buying and rest assured they have chosen a safe and effective solution.

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