Comparative analysis between the chlorination and ultraviolet radiation methods for the disinfection of bacteria-contaminated water

Abstract

The quality of water for human consumption has been a concern for large organizations and researchers, since the disinfection process, a step of great importance in water treatment plants, has not achieved its proper purpose. There have been frequent reports of the ineffectiveness of bacteria inactivation by the use of chlorine, which is the most used in Brazil, and also due to the formation of by-products such as trihalomethanes and haloacetic acids that are considered toxic to human health. The method of disinfection by ultraviolet radiation (UV) has been widely explored, due to its effectiveness in inactivating a wide variety of pathogens, in addition to the absence of by-product formation. The combined chlorine+UV process as chemical and physical disinfectants, respectively, is complementary and essential when looking for the safety of water for human consumption. The objective of this research was to statistically analyze the performance of disinfectants, chlorine and UV radiation, both separately and together, by inactivating the bacteria Escherichia coli and Pseudomonas aeruginosa and then incubating for 48 hours after having received the treatments. The statistical method showed that chlorine and UV obtained the same significance of 100% bacteria inactivation, and that within the determined time of 48 hours after the treatments the bacteria did not show reactivation. Thus, the study affirmed the usefulness of applying UV radiation as a complement to systems that use chlorine, with a special focus on residential water systems and supply.

Eficácia das medidas domiciliares de desinfecção da água para consumo humano: enfoque para o contexto de Santarém, Pará, Brasil

“…Os frascos lacrados foram abertos no momento dos ensaios. Adicionou-se uma gota de hipoclorito de sódio 2,5% em 500mL de cada Frasco Teste (1, 2 e 3), seguindo as recomendações do Ministério da Saúde 10 . Posteriormente, 100mL foram incubados em estufa microbiológica a 35±0,5ºC por 24 horas com meio de cultura Colilert.…”

“…Em seguida, foram preenchidas com a água preparada para esse estudo, e as análises foram realizadas. A água foi exposta ao sol por seis horas 10 . Para esse ensaio, a temperatura foi controlada, mantendo-se durante o período avaliado entre 30 e 31ºC, com umidade atmosférica de 75% e índice UV de 9 (muito alto).…”

Deactivating environmental strains of Escherichia coli, Enterococcus faecalis and Clostridium perfringens from a real wastewater effluent using UV-LEDs

“…UV-LEDs for water disinfection is a promising technology due to several characteristics [ 1 ]: possibility of wavelength selection, non-toxicity (vs. UV lamps containing mercury), instantaneous switch-on-off (no need of warming-up times, possibility of use of pulsed illumination, therefore saving energy), low operating working temperatures (25–30 °C), flexible architecture to design reactors, use of continuous current that allows direct connection with photovoltaic systems, longer lifetime when pulsed illumination is used, etc. [ 2 , 3 ]. But they also face some important constraints that hamper their widespread: economic cost, low efficiency and low power output [ 4 ].…”