The use of a solar simulator device to standardize microbiological decontamination of contaminated water by solar disinfection by the SODIS and MB/SODIS protocols.

Abstract

Consuming microbiologically-contaminated water is the primary cause of many water-borne diseases and deaths worldwide. Governments aim at providing drinking water for vulnerable populations, especially through low-cost interventions. Therefore, the solar disinfection (SODIS) of such pathogens provides a simple and cost-effective way to obtain good quality water. In this procedure, PET bottles are filled with contaminated water and exposed to sunlight for 1-2 days. To accelerate decontamination, methylene blue (MB) dye added as a photocatalyst, boosts singlet oxygen generation upon absorbing red-band sunlight. This study explores the use of a Sunlight Simulator (SSL) device to research and standardize the SODIS method with a vital dye as MB. PET bottles were filled with artificially-contaminated water with Streptococcus epidermidis and Deinococcus radiodurans Gram-positive bacteria, Escherichia coli and Salmonella typhimurium Gram-negative bacteria, or bacteriophage λ as well. In all experiments, 50 ng/mL MB ensued a synergistic lethal effect after SSL exposure. The results indicate that bacterial and bacteriophage inactivation can be achieved in shorter times with MB-SSL treatment compared to SSL without MB. In this sense, when compared to previous sunlight-SODIS results, the SSL source is a reliable tool to study the parameters of both SODIS and MB-SODIS protocols, and also a feasible tool to afford assays whenever there are unfavorable climate conditions.