Applied Catalysis B: Environmental 198 (2016) 431–446 Contents lists available at ScienceDirect Applied Catalysis B: Environmental j ourna l h om epage: www.elsevier.com/locate/apcatb Review Solar disinfection is an augmentable, in situ-generated photo-Fenton reaction—Part 2: A review of the applications for drinking water and wastewater disinfection Stefanos Giannakis a , María Inmaculada Polo López b,c , Dorothee Spuhler a , José Antonio Sánchez Pérez c,∗ , Pilar Fernández Ibá ˜ nez b,c,∗ , César Pulgarin a a SB, ISIC, Group of Advanced Oxidation Processes, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 6, 1015 Lausanne, Switzerland b Plataforma Solar de Almería—CIEMAT, P.O. Box 22, 04200 Tabernas, Almería, Spain c CIESOL, Joint Centre of the University of Almería-CIEMAT, 04120 Almería, Spain a r t i c l e i n f o Article history: Received 1 April 2016 Received in revised form 28 May 2016 Accepted 2 June 2016 Available online 3 June 2016 Keywords: Near-neutral photo-Fenton Drinking water Secondary wastewater disinfection Unconventional photo-Fenton Natural solar radiation Compound parabolic collector a b s t r a c t This is the second part of a comprehensive review article about photo-Fenton reaction at near-neutral pH used for water and wastewater disinfection. In this part, a critical revision of the fundamental physi- cal, chemical and biological parameters affecting the photo-catalytic process efficiency are discussed. The effects of the chemical aspects, considered either as facilitators or competitors of photo-Fenton are deeply analyzed, with special focus on organic matter and its effect over bacterial inactivation. The role of sol- ubilized iron and the biological nature of different pathogens are deeply assessed according to reported experimental data. Water temperature, turbidity, and radiation parameters like solar UV energy, ligh scattering and absorption during photo-Fenton are pictured in terms of treatment efficiency and suitable reactor design. Recent unconventional photo-Fenton strategies using iron chelates, iron oxides (including zero valent iron) and iron-based materials are also highlighted as new approaches to this process. Finally, the existing pilot scale studies in real conditions using photo-Fenton at near-neutral pH are revised, while alternative options and further research for real implementation are proposed. © 2016 Elsevier B.V. All rights reserved. Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 432 2. Chapter I: secondary MWWTP effluents: antagonism and synergy in the photo-Fenton reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433 2.1. Differences between natural waters and secondary effluents—extrapolation from nature to man-made effluents . . . . . . . . . . . . . . . . . . . . . . . . .433 2.2. Facilitators of the photo-Fenton reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433 2.3. Solubilization of iron in MWWTP secondary effluents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434 2.4. Competitors and inhibitors of the disinfection process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435 2.5. Influence of the nature (natural & collection) and microorganism species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435 3. Chapter II: effect of the operational parameters—shifting the equilibrium of the photo-Fenton process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437 3.1. Fenton reagents (Iron/H 2 O 2 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437 3.2. Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 438 3.3. Solar radiation: irradiance, cumulative dose & time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 438 Abbreviations: AOP, advanced oxidation process; ARB, antibiotic-resistant bacteria; ARG, antibiotic-resistant genes; CPC, compound parabolic collector; DBPs, disinfection by-products; DOM, dissolved organic matter; EDDS, (S,S)-Ethylenediamine-N,N ′ -disuccinic acid; EDT, effective disinfection time; EfOM, efluent organic matter; HO • , hydroxyl radical; MWWTP, municipal wastewater treatment plant; NOM, natural organic matter; NTU, nephelometric turbidity unit; NP, nanoparticles; PET, polyethylene tetrapthalate; QUV, cumulated solar UV-A energy; ROS, reactive oxygen species; SOD, superoxide dismutase; SODIS, solar disinfection; TOC, total organic carbon; UV, ultraviolet (light); UVA, ultraviolet A (light); Vis, visible (light); ZVI, zero valent iron; NZVI, nanoscale zero valent iron; ZVINP, zero valent iron nanoparticles. ∗ Corresponding authors at: CIESOL, Joint Centre of the University of Almería-CIEMAT, 04120 Almería, Spain. E-mail addresses: jsanchez@ual.es (J.A.S. Pérez), pilar.fernandez@psa.es (P.F. Ibá ˜ nez). http://dx.doi.org/10.1016/j.apcatb.2016.06.007 0926-3373/© 2016 Elsevier B.V. All rights reserved.