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The interest in developing alternative water disinfection methods that increase the access to irrigation water free of pathogens for agricultural purposes is increasing in the last decades. Advanced Oxidation Processes (AOPs) have been demonstrated to be very efficient for the abatement of several kind of pathogens in contaminated water. The purpose of the current study was to evaluate and compare the capability of several solar AOPs for the inactivation of resistant spores of agricultural fungi. Solar photoassisted HO, solar photo-Fenton at acid and near-neutral pH, and solar heterogeneous photocatalysis using TiO with and without HO, have been studied for the inactivation of spores of Curvularia sp., a phytopathogenic fungi worldwide found in soils and crops. Different concentrations of reagents and catalysts were evaluated at bench scale (solar vessel reactors, 200mL) and at pilot plant scale (solar Compound Parabolic Collector-CPC reactor, 20L) under natural solar radiation using distilled water (DW) and real secondary effluents (SE) from a municipal wastewater treatment plant. Inactivation order of Curvularia sp. in distilled water was determined, i.e. TiO/HO/sunlight (100/50mgL)>HO/sunlight (40mgL)>TiO/sunlight (100mgL)>photo-Fenton with 5/10mgL of Fe/HO at pH3 and near-neutral pH. For the case of SE, at near neutral pH, the most efficient solar process was HO/Solar (60mgL); nevertheless, the best Curvularia sp. inactivation rate was obtained with photo-Fenton (10/20mgL of Fe/HO) requiring a previous water adicification to pH3, within 300 and 210min of solar treatment, respectively. These results show the efficiency of solar AOPs as a feasible option for the inactivation of resistant pathogens in water for crops irrigation, even in the presence of organic matter (average Dissolved Organic Carbon (DOC): 24mgL), and open a window for future wastewater reclamation and irrigation use.

Highlights• Commercial cartridge filters are effective in household water treatment systems.• Upon cake formation, two pleated filters in series removed 100% of turbidity.

In this study, disinfection of urban wastewater (UWW) with two solar processes (H2O2-20 mg/L, and photo-Fenton 10 mg/L-Fe 2+ /20 mg/L-H2O2 at natural water pH) at pilot scale using a 60L-Compound Parabolic Collector reactor for irrigation of raw-eaten vegetables (lettuce and radish) has been investigated. Several microbial targets (total coliforms, Escherichia coli, Salmonella spp, and Enterococcus spp) naturally occurring in UWW and 74 organic microcontaminants (OMCs) were monitored. Disinfection results showed no significant differences between both processes, showing the following inactivation resistance order: Salmonella spp. < E. coli < total coliforms < Enterococcus spp. Reductions of target microorganisms to concentrations below the limit of detection (LOD) was achieved in all cases with cumulative solar UV (QUV) ranged from 12 to 40 kJ/L (90 min to 5 hours). Solar photo-Fenton showed a reduction of 66% of OMCs and solar/H2O2 of 56% in 4 hours treatment. Irrigation of radish and lettuce with solar treated effluents, secondary effluents and mineral water was performed for 6 and 16 weeks, respectively. The presence of bacteria was monitored in surfaces and uptake of leaves, fruit and also in soil. The bacterial concentrations detected were below the LOD in the 81.2% (lettuce) and the 87.5% (radish) of the total number of samples evaluated. Moreover, uptake of OMCs was reduced above 70% in crops irrigated with solar treated effluents in comparison with secondary effluents of UWW.