Kinetics of helminth eggs inactivation in water and digested sludges by saturated steam produced with methane from anaerobic digestors. / Inativação térmica de ovos de helmintos em água e em biossólidos digeridos: cinética em reator batelada e modelagem matemática em reator tubular.

AUTOR(ES)

Marilza de Fátima Simoneti

DATA DE PUBLICAÇÃO

2006

RESUMO

Biological sludge can be a valuable resource for agricultural soil conditioning. However, an important obstacle for its use is the usual presence of pathogenic organisms, capable of disease dissemination. The main occurring pathogens are virus, bacteria, protozoa and helminth. Helminth eggs are very resistant to thermal inactivation. The Ascaris lumbricoids sp. are by far the most conspicuous and resistant among helminths, reason why they have been chosen as indicator organisms for this research. The main available systems to inactivate sludge pathogens are composting, drying and thermal treatment, anaerobic thermofilic digestion, beta and gamma radiation, and pasteurization. Pasteurization through application of saturated steam, produced from burning of methane gas, generated in anaerobic digestors is a very simple technology involving low capital costs and needing relatively small areas for implementation. It can be a valuable technology to attend conditions prevailing in large metropolitan areas of industrializing countries. Thermal inactivation of helminth eggs in water and sludge is the main purpose of this investigation. Kinetics studies of thermal inactivation by saturated steam was performed using batch reactors. Application of the integral method has allowed for the determination of reaction orders, the specific constants of thermal die away as well as the activation energies. The helminth eggs (Ascaris suum) utilized have been obtained from uterus of adult females and the Yanko method was utilized for the recovery of eggs from the digested sludge. In the same way the thermal inactivation of Ascaris eggs in water and in digested sludge has been performed in continuous process by mathematical modeling of a plug flow reactor. The proposed models were the isothermic plug flow reactor with a non-ideal flow profile and with an axial temperature profile and ideal flow. The experimental data has shown a better adjustment to the isothermic plug flow reactor.

ASSUNTO(S)

ascaris biossólidos ascaris biosolids kinetics cinética

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