Remoção de nitrogênio de lixiviado de resíduos sólidos urbanos por meio do processo nitrificação/desnitrificação via nitrito em reator em bateladas sequenciais / Nitrogen removal from solid waste leachate by nitrification/denitrification via nitrite in a sequencing batch reactor.

AUTOR(ES)

Bruno de Oliveira Freitas

DATA DE PUBLICAÇÃO

2009

RESUMO

The leachate is an effluent with high potential to cause environmental problems in receiving body due to the high concentrations of ammoniacal nitrogen. Currently, several treatment processes have been studied to promote nitrogen removal by the hand of conventional process variations. Therefore, the present study was developed to evaluate the performance of a sequencing batch reactor (SBR) in order to promote nitrogen removal from sanitary landfill leachate, by nitrification/denitrification via nitrite process, using ethanol as source of organic matter, without the control of dissolved oxygen concentration, pH and temperature. The study was carried out in a SBR (volume of 15L). The work was divided into three phases: Phase 1 Biomass adaptation to leachate, accomplished through the gradual increasing in the volume of leachate inlet into SBR, Phase 2 - Operation of the reactor (total cycle time of 48h) and Phase 3 - Operation of the reactor (total cycle time of 72h). All phases were developed without control of pH, temperature and concentration of dissolved oxygen. In Phase 2 the nitrogen removal was evaluated in the reactor running as follows: 24h for aerobic reaction, 22.5h for anoxic reaction, 1h for settling and 0.5h for disposal/refill. In Phase 3, the influence of aerobic reaction time in the nitrogen removal was evaluated. The total cycle time was 72h, carried out as follows: 48h for aerobic reaction, 22.5h for anoxic reaction, 1h for settling and 0.5h for disposal/refill. In according to the results, the biomass adaptation to leachate occurred within 28 days of the SBR operation. The nitrite accumulation was observed after the 6th day of monitoring (86 mg NO2-N/L), which enabled the nitrogen removal via nitrite pathway. The mean conversion of ammoniacal nitrogen was 99.96% and 99.99% in Phase 2 and 3, respectively. There was not difference in the conversion of nitrogen due to aeration time. The nitrogen removal in Phase 2 ranged from 22 to 93%, mean 75 16% and in Phase 3 ranged from 53 to 92%, mean of 82 12%. Because of the leachate characteristics, especially the high pH values (average of 8.3), high concentrations of ammoniacal nitrogen (average of 1224 mg NH3-N/L) and SBR operating conditions, the SBR was able to promote nitrite accumulation and perform the nitrogen removal by nitrification/denitrification via nitrite pathway, saving 39.7% of the external source of organic matter.

ASSUNTO(S)

reator em bateladas seqüenciais resíduos sólidos urbanos sequencing batch reactor urban solid waste acúmulo de nitrito biological nitrogen removal lixiviado remoção biológica nitrogênio leachate nitrite accumulation recursos hidricos

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