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High energy planetary ball milling was applied to prepare sono-Fenton nanocatalyst from natural martite (NM). The NM samples were milled for 2-6h at the speed of 320rpm for production of various ball milled martite (BMM) samples. The catalytic performance of the BMMs was greater than the NM for treatment of Acid Blue 92 (AB92) in heterogeneous sono-Fenton-like process. The NM and the BMM samples were characterized by XRD, FT-IR, SEM, EDX and BET analyses. The particle size distribution of the 6h-milled martite (BMM) was in the range of 10-90nm, which had the highest surface area compared to the other samples. Then, the impact of main operational parameters was investigated on the process. Complete removal of the dye was obtained at the desired conditions including initial pH 7, 2.5g/L BMM dosage, 10mg/L AB92 concentration, and 150W ultrasonic power after 30min of treatment. The treatment process followed pseudo-first order kinetic. Environmentally-friendly modification of the NM, low leached iron amount and repeated application at milder pH were the significant benefits of the BMM. The GC-MS was successfully used to identify the generated intermediates. Eventually, an artificial neural network (ANN) was applied to predict the AB92 removal efficiency based upon the experimental data with a proper correlation coefficient (R=0.9836).

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Numerous water disinfection studies have reported deviations from the Chick-Watson Law, which was used to develop the Ct tables provided by the USEPA's SWTR. Some of the modifications of the Chick-Watson Law incorporate explicit dependence on initial microbial density. In this study, a series of inactivation experiments were conducted with Escherichia coli cultured under three different growth conditions to investigate cell density effects on inactivation. Cell density dependent inactivation was observed in E. coli cultures grown on nutrient agar slant overnight and grown in chemostat with hydraulic residence time of 110 h. The disinfection efficiency was significantly (P < 0.05) greater at higher initial microbial density. Inactivation of E. coli cultured in nutrient broth for only 3 h was independent of cell density. These results have a major significance for utilities in terms of optimization of the disinfection process and balancing the risks associated with exposure to pathogens and disinfection/disinfectant byproducts. Résumé :De nombreuses études de désinfection de l'eau ont fait état d'écarts par rapport à la loi de Chick-Watson, qui a été utilisé pour développer les tableaux Ct fournis par le SWTR de USEPA. Certaines des modifications de la loi de Chick-Watson incorporeng explicitement une dépendance à l'égard de la densité microbienne initiale. Dans cette étude, une série d' expériences d'inactivation ont été menées avec Escherichia coli en culture dans trois conditions différentes de croissance afin d'étudier les effets de la densité des cellules sur l'inactivation. L'inactivation liée à la densité de cellules a été observée dans les cultures de E. coli cultivée de nuit avec des éléments nutritifs sur gélose oblique et cultivée dans du chémostat avec des temps de séjour hydraulique de 110 heures. L'efficacité de la désinfection a été significativement (P < 0,05) supérieur à une plus grande densité microbienne initiale. L'inactivation de E. coli cultivée en bouillon nutritif pendant seulement 3 heures était indépendante de la densité des cellules. Ces résultats ont une grande importance pour les services publics en termes d'optimisation du processus de désinfection et d'équilibre des risques associés à l'exposition à des agents pathogènes et des sous-produits de la désinfection ou des désinfectants.

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