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Advisor(s)
Abstract(s)
A produção de resíduos biodegradáveis, incluindo subprodutos de origem animal, tem vindo a crescer
ao longo dos anos, enquanto que os solos, por oposição, estão progressivamente a perder matéria
orgânica, resultado de práticas de cultivo intensivas e exposição a condições climáticas adversas.
Pode definir-se a compostagem como uma decomposição biológica aeróbia da matéria orgânica,
produzindo um material estável, higienizado, benéfico para os solos e para o crescimento vegetal. Em
geral, tem sido admitido que, se os processos de compostagem forem operados de forma adequada,
é assegurada a higienização do composto final. O binómio temperatura/tempo de exposição é
referido como a condição mais importante na inativação dos agentes patogénicos.
A investigação no domínio da compostagem tem-se multiplicado nas décadas mais recentes,
orientada tanto para o estudo dos fenómenos a montante como a jusante do processo. Com o
presente trabalho pretendeu destacar-se algumas das temáticas essenciais da compostagem
nomeadamente, fundamentos e fatores críticos do processo, inativação e sobrevivência de
microrganismos patogénicos, considerações sobre subprodutos animais, bem como validar, em
ambiente industrial, um modelo para verificação de parâmetros de transformação alternativos dando
cumprimento aos requisitos constantes do Regulamento de execução (UE) n.º 142/2011 e respetivas
alterações introduzidas pelo Regulamento (UE) n.º 2015/9. O modelo selecionado pretendeu ser de
fácil aplicabilidade, fiável, representativo e adequado ao sistema de compostagem multi-túnel.
Na realização experimental utilizou-se um meio de cultura contendo uma concentração elevada
(aproximadamente 108 UFC.ml-1) de um organismo indicador, Enterococcus faecalis estirpe ATCC
29212. A validação dos parâmetros de transformação alternativos decorreu em três túneis de 1.ª fase
e em um túnel de 2.ª fase de compostagem, todos com controlo automático e contínuo de
temperatura. A análise dos resultados experimentais permitiu concluir que, no caso sistema multitúnel
da Central de Valorização Orgânica Lipor e para a mistura utilizada, um período de exposição
de 24 horas e uma temperatura de 60 °C asseguram as condições de higienização exigidas pela
regulamentação aplicável aos subprodutos animais. Os resultados experimentais demonstraram uma
redução superior a 7 unidades logarítmicas para Ent. faecalis. Foi também verificado no composto o
nível de Ent. faecalis de modo a detetar qualquer situação de crescimento do referido organismo após
a conclusão do processo de compostagem. Os valores obtidos (< 1,0x101.g-1) revelaram que não
houve crescimento de Ent. faecalis, refletindo um grau de estabilização (e maturação) elevado do
composto, não possibilitando qualquer fenómeno de repovoamento.
The production of bio-waste, including animal by-products, has been growing over the years, while the soil, by contrast, is gradually losing organic matter, resulting from intensive farming practices and exposure to adverse weather conditions. Composting can be defined as an aerobic biological decomposition of organic matter, producing a stable material, sanitized, beneficial for the soil and plant growth. In general, it has been accepted that if the composting processes are operated appropriately, the hygienisation of the final compound is ensured. The temperature/exposure time is referred to as the most important condition in the inactivation of pathogens. The research in the field of composting has multiplied in recent decades, driven both the study of phenomena upstream and downstream of the process. The present work was intended to highlight some of the key topics of composting, namely fundamentals and critical factors of the process, inactivation and survival of pathogenic microorganisms, considerations of animal by-products, as well as validate, in an industrial environment, a model to check alternative transformation parameters in compliance with the requirements of the Implementing Regulation (EU) No 142/2011 and respective changes introduced by Regulation (EU) No 2015/9. The selected methodology intended to be easy to apply, reliable, representative and suitable for multi-tunnel composting system. During the experiment a spiked culture containing a high concentration (approximately 108 UFC.ml-1) of an indicator organism, Enterococcus faecalis strain ATCC 29212, was used. The validation of alternative transformation parameters held in three tunnels of 1st phase and in a tunnel of 2nd composting phase, all with automatic and continuous monitoring of temperature. The analysis of experimental results concluded that, for a multi-tunnel system as Central de Valorização Orgânica Lipor and the same mixing input, a period of exposure of 24 hours and a temperature of 60 °C ensure the sanitation conditions required under the guidelines applicable to animal by-products. The experimental results showed a reduction of more than 7 log cycles for Ent. faecalis. The level of Ent. faecalis in compost was evaluated to detect any growth of the organism after the conclusion of the composting process. The values obtained (<1,0x101.g-1) showed no growth Ent. faecalis, reflecting a high degree of stabilization (and maturity) for compost, not allowing any regrowth phenomenon.
The production of bio-waste, including animal by-products, has been growing over the years, while the soil, by contrast, is gradually losing organic matter, resulting from intensive farming practices and exposure to adverse weather conditions. Composting can be defined as an aerobic biological decomposition of organic matter, producing a stable material, sanitized, beneficial for the soil and plant growth. In general, it has been accepted that if the composting processes are operated appropriately, the hygienisation of the final compound is ensured. The temperature/exposure time is referred to as the most important condition in the inactivation of pathogens. The research in the field of composting has multiplied in recent decades, driven both the study of phenomena upstream and downstream of the process. The present work was intended to highlight some of the key topics of composting, namely fundamentals and critical factors of the process, inactivation and survival of pathogenic microorganisms, considerations of animal by-products, as well as validate, in an industrial environment, a model to check alternative transformation parameters in compliance with the requirements of the Implementing Regulation (EU) No 142/2011 and respective changes introduced by Regulation (EU) No 2015/9. The selected methodology intended to be easy to apply, reliable, representative and suitable for multi-tunnel composting system. During the experiment a spiked culture containing a high concentration (approximately 108 UFC.ml-1) of an indicator organism, Enterococcus faecalis strain ATCC 29212, was used. The validation of alternative transformation parameters held in three tunnels of 1st phase and in a tunnel of 2nd composting phase, all with automatic and continuous monitoring of temperature. The analysis of experimental results concluded that, for a multi-tunnel system as Central de Valorização Orgânica Lipor and the same mixing input, a period of exposure of 24 hours and a temperature of 60 °C ensure the sanitation conditions required under the guidelines applicable to animal by-products. The experimental results showed a reduction of more than 7 log cycles for Ent. faecalis. The level of Ent. faecalis in compost was evaluated to detect any growth of the organism after the conclusion of the composting process. The values obtained (<1,0x101.g-1) showed no growth Ent. faecalis, reflecting a high degree of stabilization (and maturity) for compost, not allowing any regrowth phenomenon.
Description
Keywords
Biorresíduos Compostagem Subprodutos de origem animal Inativação térmica Higienização Validação Enterococcus faecalis Bio-waste Composting Animal by-products Thermal inactivation Sanitation Validation