Design and evaluation of zero-energy UVC-LED reactor fitted with hand pump system for disinfection

The main source of drinking water for rural communities in India is rainwater harvesting ponds. These ponds do have a sand filtration system for turbidity removal, but the bacteriological quality of these ponds is not under compliance in most cases. In this context, Pattikadu village in Kancheepuram District (Tamil Nadu, South India) was chosen as the study area. It was observed that the biological parameter of drinking water from hand pumps exceeds the limit prescribed by Indian standards. In this work, zero-energy disinfection technology was developed using UVC-LEDs for drinking water to meet the standards. The electrical power required for the disinfection was taken from the mechanical energy from up and down movement of the hand pump lever. UVC-LEDs (λ_emission 275 ± 5 nm) were powered by a 6 V rechargeable battery which stores electrical energy by mechanical movement of the hand pump lever. An annular-type UVC-LED photo-reactor (1 litre) was developed and 100% disinfection within 6 minutes’ contact time was achieved. The UVC dose-based inactivation rate constant was 0.57 cm²/mJ. The present study demonstrated 2-log inactivation for a 4.68 mJ/cm² UVC dose. The novelty of the study is its practical applicability of a sustainable point-of-use disinfection technology which might be economically implemented in lower-income smaller communities.