Biofilm control in water by advanced oxidation process (AOP) pre-treatment: effect of natural organic matter (NOM)

Abstract

The main goal of this study was to examine the influence of natural organic matter (NOM) on the efficiency of H₂O₂/UV advanced oxidation process (AOP) as a preventive treatment for biofilm control. Pseudomonas aeruginosa PAO1 biofilm-forming bacteria were suspended in water and exposed to various AOP conditions with different NOM concentrations, and compared to natural waters. H₂O₂/UV prevented biofilm formation: (a) up to 24 h post treatment - when residual H₂O₂ was neutralized; (b) completely (days) - when residual H₂O₂ was maintained. At high NOM concentrations (i.e. 25 mg/L NOM or 12.5 mg/L DOC) an additive biofilm control effect was observed for the combined H₂O₂/UV system compared to UV irradiation alone, after short biofilm incubation times (<24 h). This effect was H₂O₂ concentration dependent and can be explained by the high organic content of these water samples, whereby an increase in NOM could enhance (•)OH production and promote the formation of additional reactive oxygen species. In addition, maintaining an appropriate ratio of bacterial surviving conc.: residual H₂O₂ conc. post-treatment could prevent bacterial regrowth and biofilm formation.

Stimulating Nitrogen Biokinetics with the Addition of Hydrogen Peroxide to Secondary Effluent Biofiltration

“…No H 2 O 2 was detected at the inlet or outlet during an operation without H 2 O 2 addition, while the DO values at the outlet were <1 mg/L, which clearly indicated maximum oxygen utilization and reflected anoxic conditions [20]. The preliminary lab-bench experiments revealed no decomposition of H 2 O 2 when mixed with effluents within the interval of the HRT (20 min), as also documented by Lakretz et al [32]. When H 2 O 2 was added, the measured H 2 O 2 concentration at the inlet was 27 ± 2 mg/L, and <1 mg/L at the outlet, which affirms full H 2 O 2 degradation.…”

“…This apparatus employs a digital camera with an illumination and magnification system to capture in-situ images of suspended particles in a flowing sample. A detailed description of this analysis is published elsewhere [32,36]. An analysis was conducted on particles of between~2 and 400 µm.…”

“…The disinfection characteristics of H 2 O 2 could limit microbial-based reactors, which depend on concentration and time (C × t). Significantly tolerant degradation rates and oxygen utilization have been observed in biofilms, in comparison to suspended bacteria, in addition to changes in microbial community structure [29][30][31][32][33]. However, the application of H 2 O 2 as a supplemental oxygen source via high-rate media filtration for NH 4 + removal at a short hydraulic residence time (HRT) has never been examined.…”

Elimination of the formation of biofilm in industrial pipes using enzyme cleaning technique

“…However, how to operate and control the whole cleaning process is difficult. Here, we will introduce the strategy of enzyme cleaning to make it more appropriated and effective.A modification of CIP method is proposed for higher efficiency by using N-acetylmuramide glycanohydrolase as catalysts whose optimal pH and temperature is 10 ± 1 and 45 ± 2 °C, respectively.The initial efficiency of enzyme cleaning was evaluated by testing the content of ATP in water sample using Clean-Trace™ (3M Corporation).Lastly, the terminal water was tested with SLYM-BART™ (HACH Corporation) to find out whether there were biofilm-forming bacteria, such as Pseudomonas aeruginosa (Lakretz et al (2011) [1]), Pseudomonas fluorescens (O’Toole and Kolter (1998) [2]), iron bacterium, etc.…”

“…Lastly, the terminal water was tested with SLYM-BART™ (HACH Corporation) to find out whether there were biofilm-forming bacteria, such as Pseudomonas aeruginosa (Lakretz et al (2011) [1]), Pseudomonas fluorescens (O’Toole and Kolter (1998) [2]), iron bacterium, etc.…”