ABSTRACT The progression of the organic loading rate (OLR) up to a certain limit increases biogas production. The limit and operation range vary according to the configuration of the reactor and are associated with other variables that generate different results with respect to biogas yield (BY) and biogas productiveness (BP). The aim of this study was to investigate the effect of the OLR on the BY and BP from swine manure in continuous stirred tank reactors (CSTRs) and upflow anaerobic sludge blanket reactors (UASBs). In the assay with the CSTR, the best operational condition was at an OLR of 0.7 gVS add L−1 reactor d−1 and a hydraulic retention time (HRT) of 18 days. At this operational condition, 0.8 LN biogas gVS add−1 of BY and 0.6 LN biogas L−1 reactor d−1 of BP were obtained. In the assay with the UASB, the best operational condition was at an OLR of 2.2 gVS add L−1 reactor d−1 and an HRT of two days, and 0.7 LN biogas gvs add−1 of BY and 1.6 LN biogas L−1 reactor d−1 of BP were obtained. The results demonstrate the effects of OLR changes on the biogas production in the CSTR and UASB, avoiding the underutilization or overloading of such equipment and enabling collaboration in projects for power generation from biogas in swine farms.

A suinocultura industrial tem como característica a geração de significativas quantidades de efluente que necessitam de tratamento. O processo de biodigestão anaeróbia surge como uma alternativa importante, de baixo custo para o tratamento e eficiente na redução da matéria orgânica das águas residuárias da suinocultura. Porém os processos anaeróbios têm sua eficiência limitada, entre muitos aspectos, pela concentração de sólidos voláteis no biodigestor e sua capacidade de mineralização da matéria orgânica em função do tempo de retenção hidráulica. Diante disso, o presente estudo teve por objetivo verificar o comportamento de um biodigestor anaeróbio de fluxo ascendente, alimentado com dejetos de suínos, mediante progressão de carga de sólidos voláteis. O estudo foi realizado em três etapas, utilizando-se como parâmetro de sólidos voláteis a 0,5; 1,0 e 1,5 kgSV m-3 d-1, respectivamente. Este modelo de biodigestor mostrou ser bastante eficaz e robusto no tratamento de efluentes da suinocultura, atingindo boa eficiência na remoção de sólidos voláteis em todas as etapas do trabalho (etapa 1: 61,38%, etapa 2: 55,18% e etapa 3: 43,18%). A produção de biogás teve relação direta com o aumento da carga orgânica, atingindo 0,14; 0,85 e 0,86 Nm³ kgSVadic., respectivamente, não havendo diferença significativa (p<0,05) na porcentagem de metano no biogás entre elas (73,7; 75,0 e 77,9%).

The industrial swine production is characterized by generation of significant effluent amounts that require treatment. The most adopted practices by Brazilian swine farmers have been wastewater storage in lagoons and its subsequent use as a biofertilizer. Nutrient accumulation in soil and water creates the need for an effective management of these residues. The anaerobic digestion process is an important alternative and low-cost treatment for organic matter reduction. However, its efficiency is limited by the digester capacity of solid degradation, especially at low hydraulic retention times. Thus, the present study aimed to verify the behavior of an upflow anaerobic digester by increasing the organic loading rate. This was accomplished in three stages using, as a parameter, volatile solids at 0.5; 1.0 and 1.5 kgVS m-3 d-1, respectively. This digester model proved to be quite robust and effective in swine manure treatment, achieving high efficiency of volatile solid removal at all stages of the study (stage 1: 61.38%; stage 2: 55.18%; and stage 3: 43.18%). Biogas production was directly related to the increasing organic load, reaching 0.14, 0.85, and 0.86 Nm³ kgVS-1add., respectively, with no significant difference (p<0.05) of biogas methane concentration among the studied stages (73.7, 75.0, and 77.9%).

Effluents from swine raising can be harmful to the environment if not correctly managed. Nitrogen (N) is usually the main element present at high concentrations in the effluent. Since the use as biofertilizer is not always a feasible alternative, the treatment of swine wastewater is necessary. Variations in N species and water solubility make the treatment difficult and expensive. Additional N removal at low cost via denitrification may be possible by recirculating nitrified effluent in the barns. In this study, raw manure (RM) was homogenized with treated effluent (TE) at RM/(RM + TE) ratios of 1.0, 0.9, 0.8, 0.7, 0.6, 0.5 and 0 in order to simulate the effect of reused water on swine wastewater nitrogen removal. Samples were collected daily during four days and analyzed for pH, oxidation-reduction potential, NH4-N, NO2-N, NO3-N and chemical oxidation demand. The oxidized nitrogen (NOx-N) half-life degradation was estimated using linear regression. NOx-N species half-life less than one day was obtained when treated effluent was combined and thoroughly homogenized with raw manure. It is suggested that combining raw manure with treated effluent (e.g. water reuse) can be a simple and cost-effective strategy to remove nitrogen from swine wastewaters.

O aumento da escala de produção agropecuária e agroindustrial traz, como consequência, a necessidade por alternativas para a mitigação dos impactos ambientais. As cadeias produtivas de proteína animal (ex.: suinocultura, bovinocultura e avicultura) produzem efluentes com elevada concentração de compostos nitrogenados. Neste contexto, o processo ANAMMOX (do inglês Anaerobic Ammonium Oxidation) se constitui em uma nova estratégia de alto desempenho visando remover compostos nitrogenados de águas residuárias, agropecuárias e agroindustriais, sob condições quimiolitoautotróficas. Este artigo apresenta uma revisão bibliográfica de trabalhos publicados nos últimos 15 anos sobre estudos deste processo, discutindo sua rota metabólica, demonstrando os micro-organismos envolvidos e os parâmetros de controle do processo, além de estudos desenvolvidos no Brasil e possíveis aplicações.

The increase in agriculture and agro-industrial scale production brings the necessity for alternatives to mitigate environmental impacts. The animal protein production chains (e.g. swine, cattle and poultry) produce effluents with high concentration of nitrogen compounds. In this context, the ANAMMOX (Anaerobic Ammonium Oxidation) process is a new strategy for nitrogen removal in a high rate from agricultural and agro-industrial wastewaters under chemolithoautotrophic conditions. This paper presents a literature review of papers published in the last 15 years about the ANAMMOX process, discussing their metabolic pathway, microorganisms, main control parameters as well as studies conducted in Brazil and application possibilities.

Este trabalho avaliou o efeito da diluição do dejeto de suíno com o efluente tratado a 50% (v/v), com vistas a aumentar a desnitrificação via fornecimento de carbono ao processo. Considerando-se a diluição estudada, a concentração média de N-NO3- na mistura foi de 47,9 + 14,5 mg L-1, e a DQO da mistura, na faixa de 17.543 + 675 mg L-1, resultando numa relação DQO/N-NO3- de 366, extremamente favorável à ocorrência da atividade desnitrificante no tanque de homogeneização da mistura. A concentração de N-NO3- foi reduzida biologicamente a 0,5 mg L-1 (cerca de 1% da concentração inicial). O procedimento testado promoveu, ainda, uma melhora na etapa de separação sólido-líquido, empregando coagulantes naturais, onde foi observado um consumo de tanino inferior ao esperado.

This study evaluated the effect of swine manure dilution with treated effluent up to 50% volumetric ratio of each part, intending to increase the denitrification by carbon feeding to the process. In studied dilution, the range of NO3--N content in the mixture was 47,9 + 14,5 mg L-1 and COD close to 17543 + 675 mg L-1, resulting in favorable denitrification activity on equalization tank due to relation COD/N-NO3- upper to 360. The NO3--N concentration was biologically reduced to 0.5 mg L-1 (around 1% of initial concentration). An improvement in solid-liquid separation efficiency using natural and synthetic organic polymers was also reached in the diluted effluent when compared to the undiluted manure.

A produção de suínos vem aumentando muito no Brasil e a contribuição da suinocultura industrial, que se baseia nos Sistemas de Produção de Animais Confinados (SPACs), tem sido cada vez mais representativa. Na região Oeste de Santa Catarina o crescente aumento da densidade de animais está associado a um passivo ambiental de grandes proporções, principalmente em virtude dos efluentes da produção dos suínos possuírem uma matriz com altas concentrações de matéria orgânica e nutrientes. São inúmeras as alternativas de processos através dos quais se pode realizar o tratamento dos dejetos de suínos: físicos, físico-químicos e biológicos; esses processos podem ser empregados de forma conjunta e sequencial. Neste trabalho se estudou um processo de separação sólido-líquido, baseado no uso de um extrato natural de taninos para a coagulação e floculação de dejeto de suínos com posterior separação gravimétrica em flotodecantador. Realizou-se a comparação da eficiência de remoção de sólidos e de nutrientes em períodos distintos, antes e após as otimizações. As modificações realizadas aumentaram a eficiência do sistema atingindo índices de 46 a 56% de redução da Demanda Química de Oxigênio (DQO), melhor compactação do lodo e diminuição no arraste de sólidos sedimentáveis do flotodencantador.

Swine production is growing fast in Brazil and the contribution of the modern swine production represented by confined animal feeding operations (CAFOs), has been very important. The high animal concentration in small areas point out a very intensive environmental impact due to the concentration of organic matter and nutrients in their effluents. There are a lot of alternatives to treat swine manure: physical physico-chemical and biological treatments; these processes can be used together and sequentialy. In this paper, a solid-liquid separation process was studied based on coagulation and flocculation with tannin extracts in a settling tank, that is used as a part of a swine manure compact treatment system to treat swine manure. The process was adjusted in a laboratory scale and some modification was introduced in the full scale plant. A comparison between the pre and post adjustment process was performed. The process modification increase the COD removal from 46 to 56% and the settled solids concentration in the effluent from settling tank was also reduced.