Absence of E. coli regrowth after Fe³⁺ and TiO₂ solar photoassisted disinfection of water in CPC solar photoreactor

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• 作者：Angela-Guiovana Rincó ; n ; Cesar Pulgarin
• 关键词：Solar water disinfection ; Photocatalysis ; TiO₂ ; Iron photo-assisted reaction ; E. coli K 12 ; Photo-Fenton ; Efficient disinfection time (EDT) ; Residual disinfection effect
• 刊名：Catalysis Today
• 出版年：2007
• 出版时间：30 June 2007
• 年：2007
• 卷：124
• 期：3-4
• 页码：204-214
• 全文大小：663 K

文摘

Field disinfection of water in a large solar compound parabolic collector (CPC) photoreactor (35–70 l) was conducted at 35 °C by different photocatalytic processes: sunlight/TiO₂, sunlight/TiO₂/Fe³⁺, sunlight/Fe³⁺/H₂O₂ and compared to the control experiment of direct sunlight alone. Experiments were carried out using a CPC and natural water spiked with E. coli K 12. Under these conditions, total disinfection by bare sunlight irradiation was not reached after 5 h of treatment; and bacterial recovery was observed during the subsequent 24 h in the dark.

The addition of TiO₂, TiO₂/Fe³⁺ or Fe³⁺/H₂O₂ to the water accelerates the bactericidal action of sunlight, leading to total disinfection by solar-photocatalysis. No bacterial regrowth was observed during 24 h after stopping sunlight exposure. For some samples, the decrease of bacteria continues in the dark. A “residual disinfection effect” was observed for these samples before reaching the total inactivation. The effective disinfection time (EDT₂₄), defined as the treatment time required to prevent any bacterial regrowth during the subsequent 24 h in the dark, after stopping the phototreatment, was reached in the presence but not in the absence of different photocatalytic systems. EDT₂₄ was 2 h 30 min, 2 h and 1 h 30 min for sunlight/TiO₂, sunlight/TiO₂/Fe³⁺ and sunlight/Fe³⁺/H₂O₂ systems, respectively. The post irradiation events observed when the phototreated water is poured into an optimal growth medium are also discussed.