-This paper discusses the performance of an 800m 3 full-scale UASB reactor in treating meatpacking plant and slaughterhouse effluents containing high concentrations of oil and grease (O&G) (413-645 mg/L), resulting in a COD/O&G ratio of 26-32%. Those macromolecules were considered responsible for the unbalance of the system resulting in a total washout of the biomass. The removal of O&G from the influent using a physicochemical system (coagulation-flocculation) improved the physical characteristics of the anaerobic sludge, controlling the biomass washout. Reactor performance was significantly improved when the COD/O&G ratio influent was maintained in the 10%. The COD and O&G removal rates obtained after implantation of the physicochemical system were 70-92% and 27-58%, respectively. The specific methanogenic activity (SMA) of the biomass shows towards a tendency stabilisation and adaptation to the substrate influent. Pretreatment of the influent allowed the maximum organic load to be increased (1.46 to 2.43 Kg COD/m 3 .d) and improved the quality of the effluent.
RESUMO Neste estudo de caso, comparou-se o potencial impacto ambiental gerado por dois cenários representativos de duas formas diferentes de gerenciamento de resíduos domésticos: o primeiro com central de triagem e aterro sanitário, e o segundo com central de triagem, compostagem e aterro sanitário. A análise dos dados baseou-se nas fases de estudo de uma Análise do Ciclo de Vida: definição de objetivo e escopo, análise de inventário, avaliação dos potenciais impactos ambientais, interpretação dos resultados e avaliação crítica. Foram elaborados fluxogramas dos processos produtivos, delimitadas as fronteiras dos sistemas e elaborados os diagramas de blocos e as planilhas de aspectos e impactos ambientais. No inventário efetuado, percebe-se que os dados são favoráveis ao Cenário 2 (aterro sanitário precedido de compostagem) com relação à geração de resíduos e de emissões atmosféricas. No Levantamento dos Aspectos e Impactos Ambientais (LAIA) do Cenário 1 (com triagem de recicláveis secos, em que todos os rejeitos são encaminhados para o aterro sanitário), verificou-se que 22,2% dos aspectos e impactos ambientais foram avaliados como significativos (ou seja, classificados como "intoleráveis" ou "sérios"). No LAIA do Cenário 2, o resultado foi de 17,6% do total avaliado, cujos dados também são favoráveis a este Cenário. Em ambos os cenários, o aspecto significativo mais relevante foi relacionado às emissões atmosféricas geradas, identificadas nos processos de coleta e transporte de resíduos e de disposição final dos rejeitos.
Gas stations constitute important point sources of soil and groundwater pollution. The leaking of hydrocarbons into the soil is a significant environment issue due to the wide-ranging occurrence of leaks and the high levels and toxicity of pollutants involved in the contamination of groundwater for human use. This study introduces a compact system developed to treat groundwater contaminated with benzene, toluene, ethyl benzene, and xylenes (BTEX) and total petroleum hydrocarbon (TPH) leaked from gas station tanks. The system comprises three units: (1) suction and volatilization of volatile organic compounds (VOCs), (2) aeration tank (to remove volatile organic substances), and (3) an adsorption packed-bed filter (activated carbon (AC) and rice husk ash, 50% each, to remove TPH). Contaminated groundwater was characterized in a pilot study and in the field. Levels of BTEX and of TPH decreased by 96% with an 8-h retention time. The results obtained show that the remediation system is highly efficient and yielded water that met the discharge standards defined in the Brazilian legislation, that is, maximum benzene, toluene, and xylene levels of 5, 170, and 300 μg/L, respectively.
The challenge of developing country governments in municipal solid waste management (MSWM) is complex, often ineffective, and does not meet the required technical sustainability, which involves environmental, social, and financial aspects. The purpose of this research is to analyze two distinct waste management systems, in São Leopoldo (Brazil) and in Zurich (Switzerland), to develop a tool called “waste stream mapping” and also to compare the cities systems. The results show positively that the two municipalities have selective waste collection, however in São Leopoldo it was found that less volume was reinserted in the production chain, which considerably increases the volume of waste sent to sanitary landfill, which is the main method of disposal in Brazil. On the other hand, the Zurich management model is more expensive, especially compared to incineration, but its billing and power trading system ends up involving more of the population and paying for the operations, as Zurich generates more income than expenses. This study shows that each stage of waste management has its peculiarity and everything should be planned. The tool adapted from Value Stream Mapping has shown that it is useful to have a broad vision about the municipal solid waste management to be implemented.
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