A new NEREDA^® System in Switzerland: Same footprint, Double capacity

The Kloten Opfikon treatment plant is to double its capacity with an unchanged area.

Following successful pilot testing, the Kloten Opfikon (AKO) wastewater treatment plant decided to enlarge its facility based on the Nereda® process and has commissioned WABAG Water Technology Ltd. in Winterthur in autumn 2016 with the realisation of the project, which has a value of more than EUR 8 million. The capacity of the existing plant is to be increased from 65,000 to 125,000 p.e. but does not require any additional area. This space- and cost-saving expansion is possible through the employment of aerobic granulated activated sludge using the Nereda® system, as this high-performance process can be easily integrated into the existing activation tanks. WABAG is the sole supplier of Nereda® in Switzerland.

AKO treats the wastewater from the towns of Kloten and Opfikon, and from Zurich Airport. The growing population, stricter requirements regarding the quality of the purified wastewater, as well as the wish for a modern and energy-saving plant meant that comprehensive conversion work and expansion had become necessary. Therefore, the customer looked for a suitable, space-saving solution for the planned enlargement and together with WABAG successfully tested the innovative Nereda® process at the treatment plant for roughly one year.

The results showed that the process delivered outstanding performances regarding nutrient (ammonia, nitrogen, phosphorus) and solids removal. Using the Nereda® technology, the activated sludge largely assumes a compact granular form and thus settles very quickly, which as compared to other processes allows much higher activated sludge concentrations. This is a major advantage with regard to the enlargement of the Kloten Opfikon treatment plant since the extension can be realised by a relatively simple heightening of the existing activated sludge tanks. As a result, biological treatment capacity can be almost doubled using the existing area. Consequently, the conversion under continuous operation will be possible in three construction stages.

Opfikon means the second Nereda® order for WABAG in Switzerland. In the autumn of 2015, the Sarneraatal treatment plant in Alpnach (65,000 p.e.) opted for WABAG as a partner using the Nereda® process as a basis. The plant will become operative in 2017/2018.

The construction work on the Kloten Opfikon treatment plant will commence in 2019 and commissioning will take place in several stages between 2021 and 2024.

The Nereda® process was developed at the University of Delft and is marketed in the Netherlands by Royal HaskoningDHV with whom WABAG concluded a cooperation agreement at the end of 2014. To date, the process has been installed in some 30 municipal plants worldwide of which roughly half are already operational.