Waterboard Hollandse Delta (STW Rotterdam)

Meeting strict demands on nitrogen levels with ANAMMOX®

Sewage Treatment System (STW) Rotterdam has a capacity of 620,000 population equivalents and consists of two stage AB process. Waterboard Hollandse Delta was the first to decide on ANAMMOX® as the preferred process for the recovery of nitrogen from the reject water. Fifteen percent of STW’s nitrogen load originates from the digester reject water. When discharge limits became more stringent, Waterboard Hollandse Delta decided to extend the existing reactor with cost efficient and sustainable process, as treatment of the reject water from the centrifuge consumed large quantities of methanol and electric power.

The ANAMMOX® technology saves over 250 tonnes of methanol per year and 275,000 kWh electric power. Sludge production of reject water treatment is reduced by 40 tonnes of dry matter. ANAMMOX® resulted in annual savings of € 125,000 in operational costs and a reduction of STW’s carbon footprint by 500 tonnes per year. In addition, the ANAMMOX® reactor removes over 95% of the ammonium and over 85% of the nitrogen from the reject water, whilst only requiring 72 m3 of space.