ANAMMOX sidestream treatment of sludge dewatering reject liquors operational experience and lessons learned: PRESENTATION ONLY

Driessen, W.1, Veldhoven, J.2, Janssen, M.2, Went, C.3, Hobbs, E.3, van Loosdrecht, M.4, 1Paques bv,2 De Dommel, The Netherlands, 3Severn Trent Water, 4Delft Technical University, The Netherlands


Anaerobic digestion (AD) of biosolids has become a well-established process for treating biosolids. Sludge dewatering reject liquors from mesophilic anaerobic digestion (MAD) can represent a significant amount of the overall nitrogen load of the receiving sewage treatment works. This is especially true in case of combined application of thermal hydrolysis (THP) of biosolids and in case of sludge (cake) imports. Dedicated effective separate treatment of these sidestream dewatering liquors is paramount to mitigate any adverse negative effect on the receiving main sewage treatment works.

Long term operational experience of several sidestream case studies on treatment of (THP) MAD dewatering reject liquors will be presented and discussed. The sidestream treatment plants discussed have an Anammox® reactor as core technology for the removal of ammoniacal nitrogen. The Anammox® process is a single stage continuous aerated system using aerobic granular sludge (AGS) as active biomass.

Examples of lessons learnt include the addition of micro-nutrients overcoming any deficiencies of essential trace elements. Furthermore, the potentially inhibiting characteristics of THP-MAD reject liquor was successfully mitigated by various measures like pre-aeration and addition of dilution water. The sidestream plants demonstrated excellent performance in handling large fluctuations in load and composition producing effluent with stable low concentrations of ammoniacal nitrogen (NH4) and BOD.


Anaerobic digestion, Anammox, ammonia removal, Phospaq, Sidestream treatment, Thermal hydrolysis, THP


Abma, W. R., Driessen, W., Haarhuis, R. & van Loosdrecht, M.C.M. 2010 Upgrading of sewage treatment plant by sustainable & cost-effective separate treatment of industrial wastewater. Water Science and Technology WST Vol. 61 No 7, pp. 1715-1722.

Driessen, W., van Veldhoven, J.T.A., Janssen, M.P.M. & van Loosdrecht, M.C.M. 2020 Treatment of sidestream dewatering liquors from thermally hydrolysed and anaerobically digested biosolids. Water Practice and Technology WPT Vol 15 No 1. pp. 142-150. doi: 10.2166/wpt.2020.007

Driessen, W., Hendrickx, T., M. Remy & Haarhuis, R. 2018 Chapter 18: The Phospaq Process. In: Phosphorus: Polluter and Resource of the Future – Removal and Recovery from Wastewater. Edited by C. Schaum, IWA Publishing, London. UK. pp. 351-357. ISBN 9781780408354

Veldhoven, van, J.T.A., Leermakers-Doppenberg, I., Ringoot, D., Driessen, W., Vliegen, J & Klein Schiphorst, S. 2018 Building & operating a large centralised sludge treatment facility at WWTP Tilburg, Netherlands. In: Proceedings of the SMICE 2018 Conference – Sludge Management in Circular Economy, Rome, Italy, 23-25 May.

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