Caracterização de Produtos Microbianos Solúveis (SMPs) em Reatores Aeróbio e Anaeróbio de Bancada em Diferentes Condições Operacionais

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Biological wastewater treatment is characterized by aerobic and/or anaerobic bacteria that degrade pollutant organic matter and parameters such as chemical oxygen demand (COD) are usually used to assess these treatments efficiency. Biological reactors effluent COD is comprised not only of influent compounds that have not been degraded, but also of some compounds produced by microorganisms during treatment, known as SMPs (Soluble Microbial Products) in the literature. It is believed that the decrease of effluent COD in non-stressed conditions biological systems fed with typically biodegradable sewage can be straightly connected to minimizing SMP production and, even though SMP importance had already been recognized, literature review shows that only few researches were dedicated to identifying their chemical structure, as well as to relating their production to reactors operational parameters. Therefore, the main goal of this research was to characterize, through quantitative and qualitative approaches, the microbial products present in the supernatant of aerobic and anaerobic bench scale CSTR fed with glucose and acetate. As expected, SMP production in the aerobic CSTR was higher than in the anaerobic one (normalized production of SMP concerning influent COD in different operational conditions SMP/So varied from 2 to 68% in the aerobic reactor and from 9 to 27% in the anaerobic reactor). In the anaerobic CSTR, the organic load did not seem to have interfered to the conversion from influent COD to SMP (SMP/So ratio), what suggests that accumulated SMP can have come mainly from biomass decay, rather than from substrate use. However, in the aerobic CSTR the opposite seems to have happened. Concerning substrate kind, acetate use contributed to a higher normalized production of SMP in both reactors, compared to glucose (in the aerobic reactor, SMP/So was 41,9% for acetate versus 14,1% for glucose; in the anaerobic reactor, 21,9% and 16,6% for acetate and glucose, respectively). Temperature did not seem to have significantly interfered to SMP/So rate in the anaerobic reactor (18,1% at 15oC and 18,3% at 25oC). On the other hand, in the aerobic CSTR, normalized SMP production was higher at 15oC (33,8% against 18,7% at 25oC). In the aerobic reactor, COD related to protein amount represented 5 to 34% of effluent COD and carbohydrates COD was not higher than 16%; in the anaerobic CSTR, protein amount achieved its maximum at 17% of effluent COD, what confirms that the majority of effluent COD had not come from proteins and carbohydrates. As far as mass spectrometry results are concerned, SMP produced by each operational phase did not seem to have come from cell lysis or EPS. The predominance of low molecular weight SMP indicated products related to substrate use or to degrading/ hydrolysis of high molecular weight SMP.

ASSUNTO(S)

reatores aeróbio condições operacionais saneamento ambiental anaeróbio produtos microbianos solúveis

ACESSO AO ARTIGO

Documentos Relacionados