Chemistry and Ecology, 2014 Vol. 30, No. 5, 428–439, http://dx.doi.org/10.1080/02757540.2013.868889 Phosphorus removal by a fixed-bed hybrid polymer nanocomposite biofilm reactor M. Oliveira a ∗ , A.L. Rodrigues b , D. Ribeiro b , A.G. Brito b , R. Nogueira c and A.V. Machado a a Department of Polymers Engineering, Institute of Polymers and Composites/I3N, University of Minho, Guimarães, Portugal; b Department of Biological Engineering, Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, University of Minho, Braga, Portugal; c Department of Civil Engineering, Institute of Sanitary Engineering andWaste Management, University of Hannover, Hannover, Germany (Received 25 February 2013; final version received 15 November 2013) Eutrophication is one of the main challenges regarding the ecological quality of surface waters, phospho- rus bioavailability being its main driver. In this context, a novel hybrid polymer nanocomposite (HPN-Pr) biofilm reactor aimed at integrated chemical phosphorus adsorption and biological removal was conceived. The assays pointed to removal of 1.2 mg P/g of reactive phosphorus and 1.01 mg P/g of total phosphorus under steady-state conditions. A mathematical adsorption–biological model was applied to predict reac- tor performance, which indicated that biological activity has a positive effect on reactor performance, increasing the amount of reactive phosphorus removed. Keywords: eutrophication; phosphorus adsorption; hybrid nanocomposite 1. Introduction The leaching of surplus fertilisers from agriculture and the discharge of phosphorus (P)-rich wastewaters are among the most significant anthropogenic pressures on river basins.[1,2] As a consequence, severe loss of ecosystem biodiversity occurs and water abstraction is at risk when toxins are released following cyanobacteria blooms.[3] The eutrophication of aquatic environ- ments, such as lakes or rivers, has been noted since the 1950s, and the phenomenon is far from being solved, affecting 53% of European lakes and many others around the world.[4] The Euro- pean Water Framework Directive (WFD-2000/60/EC) aimed to restore water body quality by 2015, but derogations have been claimed when eutrophication is the main pressure. Currently, even when external P sources are eliminated, slow recuperation is observed due to the redisso- lution of P accumulated in sediments.[5,6] Furthermore, polyphosphates may also have a crucial role, since they gradually hydrolyse into phosphates.[2,7,8] The search for and development of technologies for P removal started in 1950s, with the aim of reducing the amount of P arriving at the water surface. Nowadays, chemical precipitation is the main commercial process used to remove P from eutrophic mediums and wastewater. It is based on the direct application of salts like aluminium, iron or calcium, industrial byproducts and ∗ Corresponding author. Email: moliveira@dep.uminho.pt, avm@dep.uminho.pt © 2014 Taylor & Francis Downloaded by [b-on: Biblioteca do conhecimento online UMinho] at 04:25 14 June 2014