Denitrification on upflow-anaerobic filter filled with coconut shells (cocos Nucifera)

This paper studied the denitrification in an upflow-anaerobic filter filled with coconut shells (Cocos nucifera). We sought to remove nitrogen in decentralized systems, reducing the diffuse contamination of groundwater and water bodies by nitrate. The upflow-anaerobic filter was operated under hydraulic retention time (HRT) of 16 h and on the bottom, there was an inflow of a combination of raw sewage and nitrified effluents from an intermittent sand filter. The research was divided into 5 stages in which there was an inflow of the following combination of raw sewage and nitrified effluent: Stage 1: 100.0%/0.0%; Stage 2: 87.5%/12.5%; Stage 3: 75.0%/25.0%; Stage 4: 62.5%/37.5%, and Stage 5: 50.0%/50.0%. The upflowanaerobic filter promoted denitrification in all stages with a quick acclimatization of the denitrifying biomass. In the most critical situation (Stage 5), in which there was an inflow of 46.9 mg L-1 of nitrate, a transformation of 98% of such compounds was found. On the effluent, the nitrate concentration obtained did not exceed 1.0 mg L-1. So we found that a simple recirculation of nitrified effluent to anaerobic filters can contribute to the reduction of diffuse pollution of nitrate in remote areas of large cities or in rural areas82474479CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFINANCIADORA DE ESTUDOS E PROJETOS - FINEPFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPES