Inactivation of simulated aquaculture stream bacteria at low temperature using advanced UVA- and solar-based oxidation methods

In this work the effect of water temperature (6 +/- 1 degrees C and 22 +/- 1 degrees C) on inactivation of bacteria (104 -106 CFU mL-1; Pseudomonas spp., Aeromonas spp. and Enterobacter spp.) in simulated aquaculture streams (SAS) using UVA based advanced oxidation processes (AOP) (H2O2-assisted UVA; photocatalysis; H2O2-assisted photocatalysis) and solar driven AOPs (H2O2-assisted solar disinfection, SODIS) was studied. Efficiency at 22 degrees C in terms of inactivation rate was higher using H2O2-assisted photocatalysis (H2O2/UVA-TiO2/polysiloxane) > H2O2-assisted UVA disinfection (UVA/H2O2 - 10 mg L-1) > photocatalysis (UVA-TiO2/polysiloxane) > UVA disinfection. At low temperature (6 degrees C) the inactivation rate increased with SODIS/H2O2 > SODIS > H2O2assisted UVA disinfection (UVA/H2O2 - 10 mg L-1) > H2O2-assisted photocatalysis (H2O2/UVA-TiO2/polysiloxane) > photocatalysis (UVA-TiO2/polysiloxane). The main results indicate that the inactivation rates increased when hydrogen peroxide (10 mg L-1) was used during H2O2-assisted UVA disinfection and photocatalysis. In addition, exposure of SAS to hydrogen peroxide for 24 h (in absence of light) at room temperature decreased the subsequent exposure UVA irradiation dose by almost four times. Drastic increase of inactivation rate was observed at low water temperature (6 +/- 1 degrees C) when UVA- and solarbased AOPs were employed compared to 22 +/- 1 degrees C. The treatment with SODIS proved to be more effective in Finland than in Spain. The effect of the low temperature (6 +/- 1 degrees C) was proposed as a critical factor during UVA disinfection (UVA/H2O2 and photocatalysis) that can increase the disinfection rate constant (kmax) by 1.3-5.2 times, leading to a reduction of the treatment costs ( euro m-3) by 1.3-3.3 times. The mechanism of observed enhanced disinfection at low water temperature (6 +/- 1 degrees C) when natural solar light and UVA are employed as irradiation sources for UVA/H2O2 and photocatalytic bacteria inactivation was proposed. No regrowth was observed in case of H2O2-assisted AOPs.This work was supported by a national research project (SUNRAS PROJECT, Project AGL2016-80507-R) funded by Ministerio de Economia y Competitividad (Plan Nacional de I + D + i (2013-2016). The research was also supported by a PIF contract (UCA/REC01VI/2017) funded by Vicerrectorado de Investigacion of Universidad de Cadiz. D. Sc. Juan Jose Rueda-Marquez is grateful for financial support from Academy of Finland within the project '' Combination of Advanced Oxidation Processes and Photobiotreatment for Sustainable Resource Recovery and Wastewater Reuse'' (application number 322339). T. Homola acknowledges financial support by Czech Science Foundation project 19-14770Y and project LM2018097 funded by the Ministry of Education, Youth and Sports of the Czech Republic. Documen

Post-treatment of real municipal wastewater effluents by means of granular activated carbon (GAC) based catalytic processes: A focus on abatement of pharmaceutically active compounds

Pharmaceutically active compounds (PhACs) widely present in urban wastewater effluents pose a threat to ecosystems in the receiving aquatic environment. In this work, efficiency of granular activated carbon (GAC) - based catalytic processes, namely catalytic wet peroxide oxidation (CWPO), peroxymonosulfate oxidation (PMS/GAC) and peroxydisulfate oxidation (PDS/GAC) at ambient temperature and pressure were studied for removal of 22 PhACs (ng L-1 level) that were present in secondary effluents of real urban wastewater. Concentrations of PhACs were measured using Ultra Performance Liquid Chromatography - Triple Quadrupole Mass Spectrometry (UPLC-QqQ-MS/MS). Catalytic experiments were conducted in discontinuous mode using up-flow fixed bed reactors with granular activated carbon (GAC) as a catalyst. The catalyst was characterized by means of N-2 adsorption-desorption isotherm, mercury intrusion porosimetry (MIP), elemental analysis, X-ray fluorescence spectroscopy (WDXRF), X-ray diffraction (XRD), thermal gravimetry and differential temperature analyses coupled mass spectrometry (TGA-DTA-MS). Results indicate that the highest efficiency in terms of TOC removal was achieved during CWPO performed at optimal operational conditions (stoichiometric dose of H2O2; TOC removal similar to 82%) followed by PMS/GAC (initial PMS concentration 100 mg L-1; TOC removal similar to 73.7%) and PDS/GAC (initial PDS concentration 100 mg L-1; TOC removal similar to 67.9%) after 5 min of contact time. Full consumption of oxidants was observed in all cases for CWPO and PDS/GAC at contact times of 2.5 min, while for PMS/GAC it was 1.5 min. In general, for 18 out of 22 target PhACs, very high removal efficiencies (> 92%) were achieved in all tested processes (including adsorption) performed at optimal operational conditions during 5 min of contact time. However, moderate (40 - 70%) and poor (< 40%) removal efficiencies were achieved for salicylic acid, ofloxacin, norfloxacin and ciprofloxacin, which can be possibly attributed to insufficient contact time. Despite high efficiency of all studied processes for PhACs elimination from urban wastewater effluent, CWPO seems to be more promising for continuous operation. (C) 2021 Elsevier Ltd. All rights reserved.Authors are grateful to staffmembers of Viikinmaki Wastewater Treatment Plant (Helsinki, Finland) for collaboration. D.Sc. Juan Jose Rueda-Marquez is thankful for financial support from Academy of Finland within the project "Combination of Advanced Oxidation Processes and Photobiotreatment for Sustainable Resource Recovery and Wastewater Reuse". D.Sc. Irina Levchuk is grateful for financial support obtained from KAUTE saatio(grant number: 201800116). D.Sc. Ana Rey is grateful for financial support from Ministerio de Economia y Competitividad (MINECO)Agencia Estatal de Investigacion (AEI) of Spain through the project CTQ2015-73168-JIN, co-financed by the European Funds for Regional Development (FEDER, UE). D. Sc. Javier Moreno-Andres is grateful for the financial support by the European Union under the 2014-2020 ERDF Operational Programme and by the Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia. Project reference: FEDER-UCA18-108023