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A compost of vegetable waste andPosidonia oceanicamixture (70 : 30% vol : vol) was testedin vitroandin vivofor its efficacy againstFusarium oxysporumf.spradicis-lycopersici(Forl), the causal agent of Fusarium wilt of Tomato (Lycopersicon esculentumcv. chourouk).The incorporation of non-sterilized VPC in the culture medium showed potent antifungal activity against Forl and complete inhibition of mycelium growth was observed for all the tested compost rates (0.5, 1, 2, 4, 6, 8, 10, 15 and 20%). However, only the highest rates (15 and 20%) of a sterilized suspension of VPC were effective in preventing mycelial growth. Nine indigenous bacterial strains isolated from VPC exhibited antagonism against Forl. Based on 16S rDNA sequence analysis, the isolates were assigned toBacillus sphaericus(B12 and BS2),Pseudomonas putidaPPS7 andBurkholderia gladioliBuC16. Under green house condition, seed inoculation by B12, BS2, PP7 and BuC16 strains protected significantly tomato againstFusarium oxysporumf.spradicis-lycopersici(Forl) attacks.

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The purpose of this research stream is to evaluate the kinetics of bacterial strains of Pseudomonas aeruginosa, to establish the influence of UV doses on the kinetics of disinfection, to study UV-resistant strains of Pseudomonas aeruginosa, and to underline the influence of suspended solids on the inactivation kinetics of these strains. Furthermore, and due to the lack of readily available information about the influence of temperature on microorganism inactivation processes subsequent to inactivation with UV radiation, a series of batch studies were performed at 5℃, 25?C, 37.5℃ and 50℃. This paper investigates the impact of UV irradiation on bacterial strains of P. aeruginosa inactivation in both primary and secondary wastewater effluents and to show the influence of filtration in the process of disinfection of water by UV irradiaton. Our results indicate that the effect of temperature within the normal operating range of most treatment plants, i.e., 25℃ to 37.5℃, was found to be not statistically significant on the kinetics of the UV disinfection process. However, the kinetics of the UV disinfection process was highly affected by system operating at extreme temperatures, i.e., at 10 and 50℃. In a temperature range of 25℃ to 37.5℃, the inactivation of P. aeruginosa strains varied according to the incubation time and did not exceed 4 U-Log. Consequently, having more than 102 organisms/100ml of P. aeruginosa in treated wastewater would cause serious health and environmental problems. Low inactivation was observed when the operating temperature was reduced to 10℃ regardless of the incubation time tested. In contrast, a considerable increase in the inactivation rate was noted when the temperature of the disinfected wastewater was increased to 50℃. Hence, as 5℃ and 50℃ are outside the operating range of most treatment plants, as in our country, Tunisia, it is reasonable to assume that the effect of temperature change on the kinetics of UV disinfection process is negligible

Sewage disinfection has the primary objective of inactivating pathogenic organisms to prevent the dissemination of waterborne diseases. This study analyzed individual disinfection, with chlorine alone, ultraviolet radiation alone, and a combined disinfection process (chlorine-UV radiation). Pseudomonas aeruginosa ATCC 15442, Escherichia coli ATCC 11229, Salmonella typhi ATCC 14028, and Clostridium perfringens were selected to evaluate the efficiency of different disinfection processes. The aim of the present study was to characterize the kinetics of chlorine (as NaHOCl) consumption, to evaluate responses of these bacterial species to the chlorination, the ultraviolet (UV) radiation, and the chlorine/UV disinfection processes in secondary wastewater using a batch laboratory reactor. Another target of this work was to study the modeling of the kinetic of water disinfection by chlorination and/or UV irradiation. Two kinetic models (Chick-Watson and Hom) were tested as to ability to scale disinfection of these bacterial species by different ultraviolet and/or chlorine doses. The results of the kinetics of chlorine consumption showed that monochloramines and trichloramines were the most important forms of residual chlorine as compared to free chlorine and dichloramines. The kinetics of inactivation of all examined bacterial strains showed that the application of the model of Hom in its original form was not representative of this kinetics of inactivation. Modification of this model, considering an initial decline of bacteria during the contact of water with chlorine, improved the results of the model. By the same, results revealed that the involved processes of UV irradiation were too complex to be approached by a simplified formulation, even in the case of specific strains of microorganisms and the use of nearly constant UV radiation intensity. In fact, the results have pointed out that the application of the Chick-Watson law is known to be inadequate to describe microbial inactivation with tailing or shoulder behavior. However, the UV kinetic studies also revealed that the first instants of exposure (2 to 10 s) to a UV intensity of 5 to 8 mW.cm-2 appeared as the deciding factors in disinfection with UV irradiation. It was shown that the combination of chlorine with UV yielded additive effects on the inactivation of bacterial strains and spectacular disinfection efficiency at a short contact time and less dose. In contrast to most studies, UV irradiation alone and chlorine alone exhibited low disinfection efficiency in inactivation of tested bacterial strains.