Effects of intermittent aeration periods on a structured-bed reactor continuously fed on the post-treatment of sewage anaerobic effluent
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This study assessed the simultaneous nitrification and denitrification processes and remaining organic matter removal from anaerobic reactor effluent treating wastewater in a single reactor. A structured-bed reactor, with polyurethane foam as support media, was subjected to intermittent aeration and effluent recirculation. Aerated/non-aerated periods varied in the range of 2/1–1/3 h. The chemical oxygen demand (COD) in the effluent remained between 26 and 42 mg L−1 throughout all the aeration conditions. Aeration periods of 1/2 h removed 80 and 26% of Total Kjeldahl Nitrogen and Total Nitrogen, respectively. A low solid production was observed during the 300 days of operation, resulting in a solid retention time of 139 days. The results indicate that the non-aerated periods generated alkalinity that favored nitrification, maintaining low COD concentrations in the effluent. The structured bed reactor presented a low solid production and effluent loss below 20 mgSSV L−1, similar to concentrations obtained in secondary decanters.
KeywordsSewage Anaerobic effluent Fixed bed reactor Intermittent aeration SND
This study was supported by FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo, Brasil) and CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brasil).
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