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1.
Eng. sanit. ambient ; 23(1): 91-100, jan.-fev. 2018. tab, graf
Artículo en Portugués | LILACS | ID: biblio-891630

RESUMEN

RESUMO O uso de lodo de esgoto na agricultura se tornou prática corrente em diversos países, sendo atrativa em muitos aspectos, principalmente no fornecimento de matéria orgânica e nutrientes ao solo. Embora os benefícios ambientais e agrícolas do uso de lodo sejam consideráveis, tal prática deve ser realizada de forma sanitariamente segura. Nesse contexto, o objetivo deste estudo foi avaliar a eficiência de um processo de higienização térmica de lodo de esgoto utilizando energia solar. O lodo era aquecido através de um trocador de calor, construído com tubos de cobre e instalado dentro do reator, no qual circula água aquecida em coletores solares planos. Foram realizados 16 ensaios experimentais em diferentes condições de irradiação solar. A inativação térmica da Escherichia coli foi avaliada através do modelo cinético de primeira ordem em condições não isotérmicas. O processo mostrou-se eficiente em ensaios realizados com irradiação solar média do período acima de 500 W.h.m-2, com redução de E. coli entre 4,2 e 7,1 log10 e de coliformes totais entre 4,8 e 7,4 log10. Os ensaios realizados em dias com menores índices de irradiação solar tiveram a eficiência de higienização comprometida, devido às baixas temperaturas atingidas pelo lodo.


ABSTRACT The application of sewage sludge in agriculture has become a common practice in many countries, which is attractive in many aspects, especially for the input of organic matter and nutrients in the soil. Despite the benefits of sludge use in agriculture and for the environment , this practice needs to be conducted considering safety aspects regarding sanitary conditions. In this context, the aim of this study was to evaluate the efficiency of a thermal disinfection process of sewage sludge using solar energy. The sludge was heated through a heat exchanger built with copper pipes and installed inside the reactor, in which water heated in flat plate solar collectors circulates. Sixteen experimental tests were performed under different solar irradiation conditions. The thermal inactivation of Escherichia coli in the reactor was evaluated using the first order kinetic model in non-isothermal conditions. The process proved effective in those tests with an average solar irradiation period above 500 W.h.m-2, and the reduction of E. coli was between 4.2 and 7.1 units log10; and between 4.8 and 7.4 units log10 of total coliforms. When tests were conducted in days with lower levels of solar irradiation, the efficiency of sanitisation was compromised, due to the low temperatures reached by the sludge.

2.
Microbiology ; (12)1992.
Artículo en Chino | WPRIM | ID: wpr-685840

RESUMEN

The combination effect of high hydrostatic pressure and moderate heat on the inactivation kinetics of Bacillus coagulans spore in phosphate buffer and UHT(Ultra High Temperature)whole milk was investigated.The pressure come-up time and corresponding log-reduction of spore inactivation were considered during pressure-thermal treatment.Bacillus coagulans spore had a much higher resistance to pressure in UHT whole milk than in phosphate buffer.Survival data were modeled using the linear,Weibull and log-logistic models to obtain relevant kinetic parameters.The tailing phenomenon occurred in all survival curves,indicating the linear model was not adequate for describing these curves.The log-logistic model produced best fits to survival curves,following by Weibull model.

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