Addition of hydrogen peroxide enhances abiotic sunlight-induced processes to simultaneous emerging pollutants and bacteria abatement in simulated groundwater using CPC solar reactors

•2,4-D was removed by the addition of 10mgL−1 of H2O2 and sunlight irradiation.•E. coli viability was completely reduced by the addition of H2O2 and sunlight irradiation.•K. pneumoniae showed high resistance and its viability was partially reduced.•Different photo-induced processes are responsible of 2,4-D and E. coli removal. [Display omitted] Results revealed that almost 90% of 2,4-D (70μgL−1), present in simulated groundwater containing 0.3mgL−1 of iron at pH 7.0, was degraded after 320min (60min t30w) of natural sunlight irradiation while the viability of Escherichia coli cells (followed by DVC-FISH) was completely reduced after 220min (40min t30w) by simple addition of 10mgL−1 of hydrogen peroxide. Klebsiella pneumoniae exhibited an especial behavior since its viability was only reduced in 3.5logs after 320min of sunlight irradiation (60min t30w). Dark experiment (in presence 10mgL−1 of H2O2) showed that Fenton processes may also play an important role reducing the 40% of 2,4-D after 320min (60min t30w) while viability of E. coli and K. pneumoniae underwent a reduction of 2.5 and 2logs respectively. Photolysis experiments were not able to degrade 2,4-D and E. coli and K. pneumoniae viability was partially reduced (2logs). Results showed that high 2,4-D abatement could be due to photo-induced and/or dark processes such as photo-Fenton and Fenton (dissolved and colloidal iron), photocatalysis (colloidal iron) and UV-B photolysis of H2O2. Viability reduction of microorganisms should be related to combined effects of UV-A+B irradiation, rising of temperature (44°C), photo-Fenton, Fenton and photocatalytic processes.