Estudo da cinética do tratamento biológico aeróbio de lixiviado de aterro sanitário

Abstract

Sanitary landfills of urban solid waste generate large quantities of leachate, effluents with high concentrations of pollutants. So, it is necessary to study processes to treat this effluent in an effective way. This study proposes leachate treatment process using aerobic bioreactor. As the landfill leachate is an effluent that is affected by variations of parameters, it was evaluated a historical of leachate parameters in its intermediate state. The mean values found for COD, BOD5, NH3-N and TKN presented 4,981 mgO2.L-1, 1,803 mgO2.L-1, 1,496 mg.L-1, and 1,699 mg.L-1, respectively. The tests were carried out on a bench scale with the objectivel of analyzing the kinetics of ammonia nitrogen consumption and reduction of the COD parameter. Five experiments were carried out on three different samples of leachate, all from the municipal solid waste landfill of Caxias do Sul (RS / BR). During the processes were carried out trials in batch system, with addition of activated carbon, aerobic respirometry tests, particle size and sludge content. The highest efficiency achieved in the consumption of ammoniacal nitrogen was 83.4% in 11 days of detention time. For the reduction in COD, the highest efficiency was 71.2%, in 6 days of detention time, with 47% of this consumption occurring in the first 12 hours of the process. The samples that contained xenobiotic compounds in their composition presented a lower yield in the ammoniacal nitrogen consumption. From the results it can be concluded that the rates of consumption of ammoniacal nitrogen during the first twelve hours, presented results close to the velocities found during six days of experiment. The specific reduction rates of the COD parameter during the first twelve hours are greater than the velocities encountered during the first six days of the experiment. The environment of activated sludge in landfill leachate decreased the performance of heterotrophic bacteria. The addition of activated carbon to the process mainly led to the reduction of the COD parameter slowly biodegradable, did not alter the performance of the heterotrophic bacteria nor did it improve sedimentation of the sludge.