The objective of this study was to investigate the disinfection efficiencies of E. coli and coliforms during the solar disinfection (SODIS) process with the presence of zero-valent iron and/or citric acid. The experimental results from a series of batch experiments showed that a treatment with neither sole UV-A (365 nm wavelength), zero-valent iron, nor citric acid effectively decreased the fraction of viable E. coli and coliforms under the experimental conditions investigated in this study.

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... ever, the simultaneous addition of zero-valent iron and citric acid during the UV-A illumination effectively decreased the fraction of viable E. coli and coliforms, meaning the co-existence of these three are required to effectively produce oxidants such as hydroxyl radical and ferryl ion. It was also demonstrated through field experiments that the technology proposed in this study can be easily implemented in our daily life using lemon juice rich in citric acid.