Systematic review of Giardia and Cryptosporidium removal and inactivation in drinking water treatment

Abstract

ABSTRACT The presence of Giardia spp. cysts and Cryptosporidium spp. oocysts in drinking water remains a major public health concern due to their low infectious dose and resistance to chlorination. This study presents a systematic review of dissolved air flotation (DAF), sedimentation, and ultraviolet (UV) disinfection performance. Following PRISMA 2020 guidelines, 40 peer-reviewed articles (1995–2021) were analyzed, yielding 237 datasets for qualitative synthesis. Results indicate that DAF achieves log10 reduction values (LRV) of 1.79–2.8 for Giardia and 1.42–3.7 for Cryptosporidium, heavily influenced by coagulant selection and operating pressure (400–600 kPa). Sedimentation shows consistent removal for Giardia (2.15–5.53 LRV) and Cryptosporidium (1.79–3.8 LRV) under optimized coagulation. UV disinfection provides robust inactivation (2–4.02 LRV) for both pathogens, though efficacy depends on UV dose and water turbidity. The findings underscore that while all three processes significantly mitigate protozoan risks, their performance is highly contingent upon operational parameters and raw water quality. These results provide a technical framework for optimizing multi-barrier treatment strategies in water utilities.