Coupling Extracts of Plant Coagulants With Solar Disinfection Showed a Complete Inactivation of Faecal Coliforms

Abstract

The small treated volume of water in polyethylene terephthalate (PET) bottles used in solar water disinfection (SODIS), and incomplete inactivation of bacteria at high water turbidity of ≥30 nephelometric turbidity units (NTU) are the major drawbacks of solar water treatment techniques. To address these problems, field experiments are conducted to inactivate faecal coliforms under natural sunlight. To assess the efficacy of large volumes, 3, 5, and 10‐L transparent plastic containers are used along with standard PET bottles (2 L) as SODIS reactors. To reduce the turbidity of the water, extracts of natural coagulants from tubers of Maerua subcordata and seeds of Moringa stenopetala are used. The results revealed that the turbidity of water and volume of containers affect the efficiency of SODIS, where the highest bacterial inactivation is observed at 10 NTU and a 0.5‐L PET bottle. However, the combined water treatment experiments of coagulation with extracts of either M. subcordata or M. stenopetala followed by SODIS on turbid water (150 NTU) showed 100% reduction of faecal coliforms with 4 h of exposure. This research demonstrates that a 10‐L container filled with water can be treated combining plant extracts with SODIS. The technology can be used for provision of safe and adequate drinking water for rural communities in developing countries.