SODIS with hydrogen peroxide: an effective household water treatment option under sub-tropical climatic conditions of bangladesh.

ABSTRACT

Solar disinfection (SODIS) is an affordable and sustainable Household Water Treatment (HWT) method endorsed by WHO. However, its limitations include longer sunlight exposure requirements, incomplete microbial inactivation, and post-SODIS microbial regrowth during monsoon and winter seasons in subtropical climates. To address these limitations, the performance of SODIS with H2O2 for microbial inactivation during the monsoon and winter seasons in Bangladesh was evaluated following the WHO HWT protocols. Moreover, the process was verified using drinking water samples collected from restaurants, households, and slums. All SODIS experiments were conducted using reflective reactors with PET bottles and plastic bags, adding 10 mg/L of H2O2, and exposing them to sunlight for 6 h. The results showed that E. coli was completely inactivated within 2 h in plastic bags and within 3 h in PET bottles during the monsoon season, achieving an LRV of > 5. In winter, both achieved an LRV > 5 within 3 h and plastic bags showed more efficient in microbial inactivation than PET bottles. The microbial inactivation rates were 5 times higher than those of conventional SODIS. No regrowth of microorganisms was observed during the subsequent post-SODIS period of 12 h and 24 h at room temperature. The study findings suggest that SODIS with H2O2 has the potential for complete microorganism inactivation with shorter sunlight exposure in subtropical climates with moderate to low solar irradiation and can be adopted as a reliable disinfection option for rural and urban communities with unsafe drinking water supply.