FLOCponia: Integração da tecnologia de bioflocos com a produção de vegetais
Arquivos
Data
2022-02-22
Autores
Pinho, Sara M. [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Aquicultura tem sido responsável por contribuir para o fornecimento de alimentos para uma população em crescimento. No entanto, para que essa contribuição continue a acontecer, métodos de produção intensivos e sustentáveis precisam ser empregados e desenvolvidos como, por exemplo, os cultivos baseados na tecnologia de bioflocos e aquaponia (integração da produção de peixes e plantas). Esta tese abordou um novo e promissor método de produção de alimentos de base aquática que é a integração da aquicultura utilizando a tecnologia de bioflocos com a produção de plantas hidropônicas, conhecida como FLOCponia. Os sistemas FLOCpônicos são uma inovação aos sistemas integrados de agri-aquicultura, onde os nutrientes do sistema de bioflocos são usados para nutrir e irrigar plantas em um subsistema hidropônico. Pesquisas com sistemas FLOCpônicos estão apenas começando e pouco se sabe sobre a produtividade de peixes e plantas, a eficiência do uso de recursos e sustentabilidade deste sistema integrado. Investigar e desenvolver os sistemas FLOCpônicos trazem vantagens para os produtores de alimentos e para a sociedade. Nesse contexto, o objetivo geral desta tese foi investigar a viabilidade técnica, a eficiência do uso de recursos e a sustentabilidade dos sistemas FLOCpônicos acoplados sob demanda para a produção de juvenis de tilápia e alface. Para isso, os seguintes objetivos foram formulados: (1) Identificar os trabalhos já realizados com FLOCponia, destacando os desafios atuais, e orientar pesquisas futuras. (2) Determinar a viabilidade técnica da produção de juvenis de tilápia e alface em sistemas FLOCpônicos acoplados sob demanda em comparação à aquaponia tradicional utilizando sistema de recirculação aquícola (RAS), à hidroponia e ao sistema de bioflocos. (3) Determinar como a redução do teor de proteína e o uso de nutrientes na dieta afetam o crescimento dos peixes e das plantas quando cultivados em sistema FLOCpônico acoplado sob demanda. (4) Investigar a eficiência dos sistemas FLOCpônicos em relação ao uso de recursos e quantidade de alimentos produzidos, bem como discutir as vantagens e desvantagens gerais da FLOCponia em comparação ao cultivo de peixes no sistema de bioflocos. (5) Avaliar e discutir a sustentabilidade da produção de peixes nos sistemas de bioflocos com e sem integração com a produção de plantas hidropônicas e, assim, fornecer insights sobre como melhorar a sustentabilidade da produção de alimentos em tais sistemas. (6) Identificar espécies de peixes adequadas para a aquaponia e discutir como a diversificação das espécies cultivas pode ser aplicada na FLOCponia. Para alcançar os objetivos de pesquisa, a tese é composta por sete capítulos. O Capítulo 1 apresenta uma introdução geral contendo um embasamento teórico sobre os tópicos que orientam esta tese, incluindo os sistemas aquícolas de bioflocos, aquaponia e os métodos para medir a eficiência e sustentabilidade destes sistemas. O Capítulo 2 revisa e analisa criticamente as pesquisas com FLOCponia em relação às configurações do sistema, qualidade da água e ciclagem de nutrientes, e os resultados produtivos de plantas e peixes. Nesse capítulo também identificamos aspectos econômicos e ambientais e discutimos as lacunas, oportunidades e desafios dos sistemas FLOCpônicos. Em geral, os sistemas FLOCpônicos parecem ser aplicáveis no curto prazo por produtores que já utilizam a tecnologia de bioflocos para produção de peixes e que buscam melhorar a eficiência da produção. Uma contribuição importante desse capítulo foi a identificação das desvantagens atuais dos sistemas FLOCpônicos. Em geral, a maioria dos problemas enfrentados na FLOCponia está relacionada ao design, à operação dos sistemas e ao destino adequado dos resíduos sólidos. O artigo de revisão apresentado no Capítulo 2 serviu como base teórica para os capítulos seguintes. Um experimento foi conduzido para investigar e avaliar a produção de juvenis de tilápia e alface em sistema FLOCpônico acoplado sob demanda, com foco principal em explorar a viabilidade técnica do mesmo em comparação com outros sistemas de produção (objetivo 2) e entender até quanto é possível aproveitar os benefícios nutricionais dos bioflocos para a produção de tilápia nesse sistema integrado (objetivo 3). Para isso, juvenis de tilápia e alface foram cultivados em sistemas FLOCpônicos acoplados sob demanda, aquaponia tradicional utilizando RAS, monoculturas em sistema de bioflocos e/ou hidroponia. Além disso, quatro dietas para peixes foram formuladas, produzidas e testadas nos sistemas FLOCpônicos. Os resultados deste experimento são relatados no Capítulo 3. Para a produção de alface, produtividades semelhantes foram encontradas nos sistemas FLOCpônicos, aquapônicos e hidropônicos. Com relação à produção de peixes, foi observado um aumento de 24% no crescimento dos peixes na FLOCponia em comparação à aquaponia utilizando RAS. Além disso, os benefícios dos bioflocos para a nutrição dos peixes foram observados em sistemas FLOCpônicos acoplados sob demanda, levando a uma redução de 8% na proteína bruta da dieta dos peixes em comparação ao sistema aquapônico utilizando RAS. Esses resultados indicaram que os sistemas FLOCpônicos acoplados sob demanda são tecnicamente viáveis e permitem a redução do teor de proteína bruta em dietas para peixes. O Capítulo 4 emprega modelos matemáticos dinâmicos para investigar a eficiência do uso de recursos do sistema FLOCpônico em comparação ao monocultivo de peixes em sistema de bioflocos. Os resultados mostraram que, em geral, o sistema FLOCpônico é mais eficiente no uso de recursos do que o sistema de bioflocos. As eficiências de uso de água e de nutrientes foram maiores na FLOCponia do que no sistema de bioflocos em 10 e 27%, respectivamente. O volume de sólidos descartados no sistema FLOCpônico foi 10% menor do que no de bioflocos. Ao realizar simulações de cenários, o sistema FLOCpônico foi ainda mais eficiente ao expandir até 3,2 vezes a área de plantio em relação ao sistema inicialmente estudado. Os resultados apresentados neste estudo de modelagem confirmam a hipótese de que a integração com a hidroponia torna a produção de peixes em bioflocos mais eficiente no uso de recursos e na prevenção de desperdícios. Avaliar a sustentabilidade dos sistemas de produção de alimentos em seu estágio inicial de desenvolvimento é essencial para identificar práticas insustentáveis e orientar pesquisas futuras que visem evitá-las. No Capítulo 5, aplicamos a síntese em emergia para comparar a sustentabilidade dos sistemas de bioflocos e hidropônicos com sua integração em FLOCponia, com base nos resultados experimentais. Os indicadores emergéticos indicaram que o sistema integrado é tão sustentável quanto as monoculturas em bioflocos e hidroponia. Além disso, o valor emergético unitário (UEV) no sistema FLOCpônico foi 104 vezes menor do que no sistema hidropônico, indicando maior eficiência. Por outro lado, o sistema FLOCpônico foi menos eficiente na conversão de energia em produtos do que o sistema de bioflocos, evidenciado pelo maior UEV do sistema integrado. A síntese em emergia do sistema FLOCpônico apontou que melhorias devem ser feitas para aumentar a eficiência do sistema e explorar todo o seu potencial para o fornecimento sustentável de alimentos. O Capítulo 6 revisa as espécies de peixes adequadas para a aquaponia como um meio de melhorar a diversificação dos sistemas integrados de agri-aquicultura. Este capítulo apresentou as características que tornam uma espécie de peixe adequada para cada layout de sistema (permanentemente acoplado ou acoplado sob demanda). Na aquaponia utilizando RAS permanentemente acoplada com o subsistema hidropônico, a escolha das espécies de peixes depende diretamente do vegetal que será cultivado. Em sistemas aquapônicos acoplados sob demanda, a aceitação do mercado, os custos de produção e a taxa de crescimento são fatores determinantes para escolha das espécies de peixes a serem cultivadas. Em geral, peixes adequados para a produção em RAS também são adequados para aquaponia utilizando RAS. As implicações das descobertas do Capítulo 6 na FLOCponia são discutidas no Capítulo 7. Em resumo, destacamos que a diversidade de produtos oferecidos pelo sistema FLOCpônicos pode ser aumentada com a produção de espécies de peixes adequadas para os sistemas baseados em bioflocos, como o tambaqui, o pacu ou o jundiá. Por último, o Capítulo 7 discute as principais conclusões da tese, destacando os avanços nas pesquisas com FLOCponia e seus impactos na sociedade. De uma perspectiva ampla, o sistema FLOCpônico pode aproximar a produção de uma grande diversidade de alimentos frescos e saudáveis ao consumidor. Isso porque o sistema FLOCpônico pode ser implantado em regiões geralmente não destinadas à produção de alimentos, contribuindo para o aumento da segurança alimentar e melhoria da distribuição de alimentos. Por fim, desenvolver os sistemas FLOCpônicos para serem sistemas de produção representativos para abastecimento de alimentos garante utilização mais eficiente dos recursos e contribui para o desenvolvimento sustentável da aquicultura.
Aquaculture has been responsible for providing healthy food for the growing population. Aquaculture contribution to the global food production scenario is expected to continuously grow through intensive and sustainable production methods, such as biofloc-based culture and aquaponics (integration of fish-plant production). This thesis explored a new aquatic-based food production method, i.e., the integration of biofloc-based aquaculture with soilless plant (hydroponics) production in so-called FLOCponics systems. FLOCponics is a special case of integrated agri-aquaculture, where nutrients from a biofloc-based culture are used to nourish and irrigate plants in a hydroponics subsystem. FLOCponics is quite a new research field, and little is known about fish and plant productivity, resource use efficiency, and sustainability of this integrated system. Developing a better understanding of FLOCponics may bring advantages to food producers and society. In this context, the overall aim of this thesis was to investigate and discuss the technical feasibility, efficiency and sustainability of on-demand coupled FLOCponics for tilapia juveniles and lettuce production. For that, the following specific objectives were formulated: (1) To identify the status quo of FLOCponics, highlight current FLOCponics challenges and give directions for further research. (2) To determine the technical feasibility of producing tilapia juveniles and lettuce in on-demand coupled FLOCponics compared to traditional (RAS-based) on-demand coupled aquaponics, hydroponics and biofloc-based monoculture systems. (3) To determine how the reduction of protein content in the fish diet affects fish and plant growth, dietary nutrient use by fish and water quality in on-demand coupled FLOCponics system. (4) To investigate the efficiency of on-demand coupled FLOCponics system in terms of resource use and amount of food produced and discuss the overall advantages and disadvantages of FLOCponics compared to biofloc-based fish culture. (5) To assess and discuss the sustainability of biofloc-based fish culture with and without integrating with hydroponic plant production and provide insights on how to improve the sustainable character of food production in such systems. (6) To identify suitable fish species for aquaponics and discuss their applicability to diversify FLOCponics’ products. To achieve the research objectives, the thesis comprises seven chapters. Chapter 1 presents a general introduction containing a brief background on the topics that guide this thesis, including biofloc-based aquaculture, aquaponics, and the methods to measure the systems’ efficiency and sustainability. Chapter 2 critically reviews and analyses the FLOCponics research regarding the system setups, water quality and nutrient recycling, and the productive results of plants and fish. In this chapter, we also identified economic and environmental aspects and discussed the gaps, opportunities, and challenges of FLOCponics systems. In general, FLOCponics systems seem to be applicable in the short-term by farmers who already operate biofloc-based fish culture and seek to improve the system efficiency. An important contribution of this chapter was the identification of current FLOCponics drawbacks that are essentially related to systems’ design and operation and proper destination of solid wastes. The review paper presented in Chapter 2 served as a theoretical basis for the following chapters. An experiment was conducted to investigate and evaluate the production of tilapia juveniles and lettuce in an on-demand FLOCponics system to explore the technical feasibility of it compared to other production systems (objective 2) and to what degree is it possible to take advantage of the nutritional benefits of biofloc for tilapia production in such system (objective 3). For that, tilapia juveniles and lettuce were cultured in on-demand coupled FLOCponics, traditional aquaponics using recirculating aquaculture system (RAS), biofloc-based monoculture, and/or hydroponics systems, and four fish diets were formulated, produced, and tested in FLOCponics systems. The findings of this experimental trial are reported in Chapter 3. We found similar lettuce yields in on-demand coupled FLOCponics, RAS-based aquaponics and hydroponics systems. With respect to fish production, FLOCponics outperforms fish yield of RAS-based aquaponics by 24%. In addition, benefits of bioflocs for fish nutrition were also seen in on-demand coupled FLOCponics systems, leading to 8% reduction in the fish dietary crude protein compared to RAS-based aquaponics. These results indicated that on-demand coupled FLOCponics systems are technically feasible and allow a reduction in the crude protein content in fish diets and thus can be used as an alternative feeding strategy in an integrated system. Chapter 4 follows a dynamic modelling approach to investigate the efficiency of FLOCponics system compared to stand-alone biofloc-based system. The results showed that, in general, FLOCponics was more efficient in using resources than the biofloc system. The water and nutrient use efficiencies were higher in FLOCponics than in biofloc system by 10 and 27%, respectively. The volume of solids discharged in FLOCponics was 10% lower than in biofloc-based fish monoculture. When performing scenario simulations, the FLOCponics system was even more efficient by expanding the planting area up to 3.2 times in relation to the nominal case. The findings presented in this model-based study support the hypothesis that integrating with hydroponics makes biofloc-based fish culture more efficient in terms of resource use and wastes avoidance. Assessing the sustainability of food production systems in their early stage of development is essential to identify unsustainable practices and guide further research to avoid them. In Chapter 5, we applied emergy synthesis to compare the sustainability of stand-alone biofloc and hydroponics systems with their integration in a FLOCponics system, based on the previews experimental results. The emergy indicators indicated that FLOCponics is as sustainable as the stand-alone biofloc and hydroponics systems. Additionally, we found that the unit emergy value (UEV) in FLOCponics was 104 times lower than in hydroponics system, indicating higher efficiency. On the other hand, FLOCponics was less efficient in converting energy to outputs than biofloc system, as the UEV of FLOCponics was 78% higher. The emergy synthesis of the FLOCponics system pointed out that further improvements must be made to increase the efficiency of the system and explore its full potential for sustainable food provision. Chapter 6 reviews fish species suitable for aquaponics as a mean to improve the diversification of integrated agri-aquaculture systems. This chapter presented the characteristics that make a fish species sustainable for each system layout (permanently or on-demand coupled). In permanently coupled RAS-based aquaponics, the choice of fish species depends on the crop grown. In on-demand coupled RAS-based aquaponics, the choice of the fish species is directly dependent on the fish market acceptance, production costs and growth rate. In general, fish suitable for RAS production are also suitable for RAS-based aquaponics. The implications of the findings of Chapter 6 on FLOCponics is discussed in Chapter 7. The diversification of FLOCponics can be increased by producing alternative fish species suitable for the biofloc-based systems, as tambaqui, pacu or jundia. Lastly, Chapter 7 discusses the main findings of the thesis, highlighting the advances in the FLOCponics research field and their social impacts. From a broad perspective, FLOCponics can bring the production of a mix of fresh and healthy food close to the consumer. That is because FLOCponics seems suitable for implementation in regions usually not destined for food production, contributing to increasing food security and fair food distribution. As a final remark, developing FLOCponics to be a representative activity for food supply guarantees more efficient use of resources and contributes to sustainable aquaculture development.
Aquaculture has been responsible for providing healthy food for the growing population. Aquaculture contribution to the global food production scenario is expected to continuously grow through intensive and sustainable production methods, such as biofloc-based culture and aquaponics (integration of fish-plant production). This thesis explored a new aquatic-based food production method, i.e., the integration of biofloc-based aquaculture with soilless plant (hydroponics) production in so-called FLOCponics systems. FLOCponics is a special case of integrated agri-aquaculture, where nutrients from a biofloc-based culture are used to nourish and irrigate plants in a hydroponics subsystem. FLOCponics is quite a new research field, and little is known about fish and plant productivity, resource use efficiency, and sustainability of this integrated system. Developing a better understanding of FLOCponics may bring advantages to food producers and society. In this context, the overall aim of this thesis was to investigate and discuss the technical feasibility, efficiency and sustainability of on-demand coupled FLOCponics for tilapia juveniles and lettuce production. For that, the following specific objectives were formulated: (1) To identify the status quo of FLOCponics, highlight current FLOCponics challenges and give directions for further research. (2) To determine the technical feasibility of producing tilapia juveniles and lettuce in on-demand coupled FLOCponics compared to traditional (RAS-based) on-demand coupled aquaponics, hydroponics and biofloc-based monoculture systems. (3) To determine how the reduction of protein content in the fish diet affects fish and plant growth, dietary nutrient use by fish and water quality in on-demand coupled FLOCponics system. (4) To investigate the efficiency of on-demand coupled FLOCponics system in terms of resource use and amount of food produced and discuss the overall advantages and disadvantages of FLOCponics compared to biofloc-based fish culture. (5) To assess and discuss the sustainability of biofloc-based fish culture with and without integrating with hydroponic plant production and provide insights on how to improve the sustainable character of food production in such systems. (6) To identify suitable fish species for aquaponics and discuss their applicability to diversify FLOCponics’ products. To achieve the research objectives, the thesis comprises seven chapters. Chapter 1 presents a general introduction containing a brief background on the topics that guide this thesis, including biofloc-based aquaculture, aquaponics, and the methods to measure the systems’ efficiency and sustainability. Chapter 2 critically reviews and analyses the FLOCponics research regarding the system setups, water quality and nutrient recycling, and the productive results of plants and fish. In this chapter, we also identified economic and environmental aspects and discussed the gaps, opportunities, and challenges of FLOCponics systems. In general, FLOCponics systems seem to be applicable in the short-term by farmers who already operate biofloc-based fish culture and seek to improve the system efficiency. An important contribution of this chapter was the identification of current FLOCponics drawbacks that are essentially related to systems’ design and operation and proper destination of solid wastes. The review paper presented in Chapter 2 served as a theoretical basis for the following chapters. An experiment was conducted to investigate and evaluate the production of tilapia juveniles and lettuce in an on-demand FLOCponics system to explore the technical feasibility of it compared to other production systems (objective 2) and to what degree is it possible to take advantage of the nutritional benefits of biofloc for tilapia production in such system (objective 3). For that, tilapia juveniles and lettuce were cultured in on-demand coupled FLOCponics, traditional aquaponics using recirculating aquaculture system (RAS), biofloc-based monoculture, and/or hydroponics systems, and four fish diets were formulated, produced, and tested in FLOCponics systems. The findings of this experimental trial are reported in Chapter 3. We found similar lettuce yields in on-demand coupled FLOCponics, RAS-based aquaponics and hydroponics systems. With respect to fish production, FLOCponics outperforms fish yield of RAS-based aquaponics by 24%. In addition, benefits of bioflocs for fish nutrition were also seen in on-demand coupled FLOCponics systems, leading to 8% reduction in the fish dietary crude protein compared to RAS-based aquaponics. These results indicated that on-demand coupled FLOCponics systems are technically feasible and allow a reduction in the crude protein content in fish diets and thus can be used as an alternative feeding strategy in an integrated system. Chapter 4 follows a dynamic modelling approach to investigate the efficiency of FLOCponics system compared to stand-alone biofloc-based system. The results showed that, in general, FLOCponics was more efficient in using resources than the biofloc system. The water and nutrient use efficiencies were higher in FLOCponics than in biofloc system by 10 and 27%, respectively. The volume of solids discharged in FLOCponics was 10% lower than in biofloc-based fish monoculture. When performing scenario simulations, the FLOCponics system was even more efficient by expanding the planting area up to 3.2 times in relation to the nominal case. The findings presented in this model-based study support the hypothesis that integrating with hydroponics makes biofloc-based fish culture more efficient in terms of resource use and wastes avoidance. Assessing the sustainability of food production systems in their early stage of development is essential to identify unsustainable practices and guide further research to avoid them. In Chapter 5, we applied emergy synthesis to compare the sustainability of stand-alone biofloc and hydroponics systems with their integration in a FLOCponics system, based on the previews experimental results. The emergy indicators indicated that FLOCponics is as sustainable as the stand-alone biofloc and hydroponics systems. Additionally, we found that the unit emergy value (UEV) in FLOCponics was 104 times lower than in hydroponics system, indicating higher efficiency. On the other hand, FLOCponics was less efficient in converting energy to outputs than biofloc system, as the UEV of FLOCponics was 78% higher. The emergy synthesis of the FLOCponics system pointed out that further improvements must be made to increase the efficiency of the system and explore its full potential for sustainable food provision. Chapter 6 reviews fish species suitable for aquaponics as a mean to improve the diversification of integrated agri-aquaculture systems. This chapter presented the characteristics that make a fish species sustainable for each system layout (permanently or on-demand coupled). In permanently coupled RAS-based aquaponics, the choice of fish species depends on the crop grown. In on-demand coupled RAS-based aquaponics, the choice of the fish species is directly dependent on the fish market acceptance, production costs and growth rate. In general, fish suitable for RAS production are also suitable for RAS-based aquaponics. The implications of the findings of Chapter 6 on FLOCponics is discussed in Chapter 7. The diversification of FLOCponics can be increased by producing alternative fish species suitable for the biofloc-based systems, as tambaqui, pacu or jundia. Lastly, Chapter 7 discusses the main findings of the thesis, highlighting the advances in the FLOCponics research field and their social impacts. From a broad perspective, FLOCponics can bring the production of a mix of fresh and healthy food close to the consumer. That is because FLOCponics seems suitable for implementation in regions usually not destined for food production, contributing to increasing food security and fair food distribution. As a final remark, developing FLOCponics to be a representative activity for food supply guarantees more efficient use of resources and contributes to sustainable aquaculture development.
Descrição
Palavras-chave
Protein, Production, Vegetable, Technology