Pharmaceuticals removal from natural water by nanofiltration combined with advanced tertiary treatments (solar photo-Fenton, photo-Fenton-like Fe(III)–EDDS complex and ozonation) S. Miralles-Cuevas a , F. Audino c , I. Oller a , R. Sánchez-Moreno a , J.A. Sánchez Pérez b , S. Malato a,⇑ a Plataforma Solar de Almería-CIEMAT, Carretera Senés km 4, 04200 Tabernas, Almería, Spain b Departamento de Ingeniería Química de la Universidad de Almería, Carretera Sacramento S/N, 04120 Almería, Spain c Departamento de Ingeniería Química de la Universidad de Nápoles ‘‘Federico II’’, Piazzale Vincenzo Tecchio 80, 80125 Nápoles, Italy article info Article history: Received 13 October 2013 Received in revised form 8 December 2013 Accepted 10 December 2013 Available online 17 December 2013 Keywords: Nanofiltration Permeate treatment Pharmaceuticals removal Solar photo-Fenton abstract The main purpose of the study was to compare three different advanced tertiary treatments, solar photo- Fenton, solar photo-Fenton-like Fe(III)–EDDS complex and ozonation. Five pharmaceuticals, carbamaze- pine, flumequine, ibuprofen, ofloxacin, and sulfamethoxazole, selected as model micropollutants for the study, were dissolved (15 lgL 1 ) in natural water. The nanofiltration system consisted of two 5.2 m 2 membranes operated in parallel. The solar photo-Fenton experiments were carried out in a 3 m 2 com- pound parabolic collector pilot plant having a 35 L total volume. The ozonation system was a pilot plant providing a maximum concentration of 8.82 g O 3 h 1 . Contaminants were measured by ultra-perfor- mance liquid chromatography, previously preconcentrated by solid phase extraction. Nanofiltration pro- vided a large volume of practically clean water (permeate) and a concentrated stream requiring further treatment. General advantages of the combined process over direct treatment due to reduction in the total volume to be treated were: (i) lower AOP treatment time, (ii) more efficient reagent consumption, and (iii) lower acid consumption for carbonate removal. The photo-Fenton-like Fe(III)–EDDS complex makes it possible to work at over pH6. Ozone consumption was lowered by combining ozonation with nanofiltration instead of using direct ozonation. Ó 2013 Elsevier B.V. All rights reserved. 1. Introduction The constant discovery of new potentially harmful contami- nants with the growing demand for water make it clear that fur- ther research is required [10]. These problems are further compounded because these new contaminants (detergents, phar- maceuticals, personal care products, flame retardants, antiseptics, industrial additives, steroids, hormones, etc.) are not eliminated by conventional biological treatments, which were designed to re- sist microorganisms [18]. The majority of hydrophobic compounds are expected to appear in higher concentrations in primary sludge because they have more affinity to solids, but the great majority of hydrophilic compounds (most pharmaceuticals and antibiotics) are contained in the effluent in ng L 1 to lgL 1 concentrations [18,21,36]. In view of this, recent studies have focused on the use of Advanced Oxidation Processes (AOPs) as tertiary treatments for eliminating such micropollutants in Municipal Wastewater Treatment Plants (MWTPs). AOPs can be defined as processes involving the formation of hydroxyl radicals (HO Å ) having an oxida- tion potential of 2.8 V, which is much higher than other traditional oxidants (for example, ozone 2.07 V; hydrogen peroxide 1.78 V; chlorine dioxide 1.57 V, and chlorine 1.36 V). These radicals are capable of oxidizing organic compounds and initiating a series of oxidative degradation reactions leading to the complete minerali- zation of contaminants [24]. The main AOPs tested for removal of these contaminants are dark oxidation, such as ozonation without radiation, Fenton or Fenton-like and oxidation processes with radi- ation, such as UV/H 2 O 2 , UV/TiO 2 or photo-Fenton. Ozonation is the dark oxidation method most used for removing micropollutants, with ozone doses of 0.1–30 mg L 1 [7,20,22]. Removal rates over 90% have previously been found for compounds, except X-ray con- trast media and clofibric acid, which seem to be more recalcitrant to dark oxidation than other contaminants [39]. AOPs using radia- tion, especially photo-Fenton, have also been highly successful for micropollutant remediation [42,28,8], and are of added interest, as solar irradiation can be used as a photon source, with removal rates over 99% [17]. On the other hand, physical processes, such as membrane nano- filtration (NF) and reverse osmosis (RO) have been shown to be the most promising systems for separation of these micropollutants [2,41]. It is known that these techniques are nondestructive, so 1383-5866/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.seppur.2013.12.006 ⇑ Corresponding author. Tel.: +34 95387940; fax: +34 950365015. E-mail address: sixto.malato@psa.es (S. Malato). Separation and Purification Technology 122 (2014) 515–522 Contents lists available at ScienceDirect Separation and Purification Technology journal homepage: www.elsevier.com/locate/seppur