The influence of Al 3+ on the anaerobic treatment of a poultry slaughterhouse wastewater was studied in this work. The soluble COD (SCOD), volatile acid (VA) concentrations, and methane yield values were measured and compared for zero, 15, and 40 ppm Al 3+ runs. Methane yields of 55.4, 144.2, and 215.4 ml CH4/g. COD for zero, 15, and 40 ppm Al 3+ concentrations, respectively, were observed. Furthermore, SCOD and VAs were not detectable in the reactor that was seeded with 40 ppm Al 3+. It was concluded that inhibitory effects of long chain fatty acids (LCFAs) on aceticlastic methanogens were reduced by aluminum ion. This conclusion was also corroborated by a new mathematical model for estimating the Monod parameters developed in this work. The main characteristic of this new model is that estimated parameters must satisfy some restrictions, which provides consistency for the estimated parameters.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aims to evaluate the emission of methane (CH4) generated in an anaerobic stabilization pond used to treat wastewater from a cattle slaughterhouse, which is located in Santa Maria, Rio Grande do Sul (RS). In addition to the quantification of CH4 by gas chromatography, it was evaluated the emissions of other greenhouse effect gases (GHG) such as carbon dioxide (CO2) and nitrous oxide (N2O). It was verified the occurrence of two types of fluxes for a release of produced methane: the diffusive, with a daily average equal to 196.0 ± 51 mgCH4m-2h-1; and the ebullient, resulting of the random and sudden release of gases in the form of bubbles with variations between 67.0 and 1295.0 mgCH4m-2h-1. The flow rates values calculated from theoretical models presented significantly higher than the experimental ones, ranging from 387.0 to 410.0 mgCH4m-2h-1, since it was not taken into account the different variables of interference in anaerobic treatment, such as the needs and interactions between bacteria, dilution of the wastewater, and physical-chemical factors. The data revealed a higher production of CO2 (55 vol%) than CH4 (45 vol%) indicating reduction in the production of CH4 and its partial oxidation caused by oscillation in the layer of foam found during the research period. The presence of N2O in the samples indicated the presence of O2 dissolved in the wastewater. The results of this study evidenced that the anaerobic ponds constitute important sources of GHG, emphasizing the importance to control the use of this technology, as a way of mitigating the emission of gaseous compounds into the atmosphere and contribute to reducing the possible negative effects in the environment. / Este trabalho objetiva avaliar a emissão de metano (CH4) gerado em uma lagoa de estabilização anaeróbia utilizada no tratamento de águas residuárias de um abatedouro de bovinos, o qual está localizado no município de Santa Maria, Rio Grande do Sul (RS). Adicionalmente à quantificação do CH4 por cromatografia gasosa, foi avaliada a emissão de outros gases de efeito estufa (GEE), tais como o dióxido de carbono (CO2) e o óxido nitroso (N2O). Foi verificada a ocorrência de dois tipos de fluxos para a liberação de metano produzido: o difusivo, com média diária igual a 196,0 ± 51 mgCH4m-2h-1; e o ebulitivo, resultante da liberação aleatória e súbita de gases na forma de borbulhas, com variações entre 67,0 e 1.295,0 mgCH4m-2h-1. Os valores de fluxos calculados a partir de modelos teóricos apresentaram-se sensivelmente maiores do que os experimentais, variando de 387,0 a 410,0 mgCH4m-2h-1, uma vez que não levaram em conta as diferentes variáveis de interferência no tratamento anaeróbio, como as necessidades e interações entre bactérias, diluição do efluente líquido, e fatores físico-químicos. Os dados revelaram uma maior produção de CO2 (55 vol%) do que de CH4 (45 vol%) indicando redução na produção de CH4 ou sua oxidação parcial causada por oscilação na camada de escuma verificada durante o período da pesquisa. A presença de N2O nas amostras indicou a presença de O2 dissolvido no efluente. Os resultados obtidos nesse estudo evidenciam que as lagoas anaeróbias constituem importantes fontes de GEE, ressaltando a importância no controle na utilização dessa tecnologia, como uma forma de mitigar a emissão de compostos gasosos para a atmosfera e contribuir para a redução nos possíveis efeitos negativos sobre o meio ambiente.