Banca de DEFESA: BARBARA COSTA PEREIRA
Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.DISCENTE : BARBARA COSTA PEREIRA
DATA : 19/02/2018
HORA: 13:00
LOCAL: Sala de Multimídia da Ensp/FIOCRUZ
TÍTULO:
Combined Treatment of Landfill Leachate and Sanitary Sewage with Activated Sludge and Monitoring of Nitrous Oxide Emission
PALAVRAS-CHAVES:
Slurry, Cotreatment, Greenhouse Gas
PÁGINAS: 82
GRANDE ÁREA: Ciências Agrárias
ÁREA: Engenharia Agrícola
SUBÁREA: Engenharia de Água e Solo
ESPECIALIDADE: Conservação de Solo e Água
RESUMO:
The combined treatment of landfill leachate with sanitary sewage by biological processes used in treatment plants has proved to be an economical and efficient alternative. However, the leachate can present toxic substances capable of compromising the efficiency of the process, and it is necessary to evaluate previously the leachate/sewage relation to be adopted. The activated sludge process is widely used in large cities and through some operational modifications can promote the biological removal of nitrogen. This is a relevant characteristic in cotreatment, since the addition of leachate represents a contribution of nitrogenous material. One of the problems in removing nitrogen is the emission of nitrous oxide (N2O), a greenhouse gas. Thus, the objective of this work was to evaluate the cotreatment of landfill leachate and sanitary sewage using a sequential batch reactor (SBR), in addition to monitoring the emissions of nitrous oxide. A reactor with a useful volume of approximately 35 L was used that operated with cycles of 6 hours. The experiment was conducted in two stages: STAGE 1 using only sanitary sewage and STAGE 2 with the addition of sanitary landfill leachate (0.5% v/v). The efficiency of removal of organic matter and nitrogen was evaluated before and after addition of the leachate as well as the emission of N2O throughout the process. The addition of leachate caused biomass decrease in addition to affecting some observed operational parameters (SVI, DO and OUR). SBR was able to remove some characteristic parameters of the leachate as true color (43%) and apparent color (88%), as well as ABS 254 (42%), high values when compared to other types of processes as activated carbon. However, the addition of leachates led to the reduction of COD removal efficiencies, DOC and NTK. In STAGE 1, COD and DOC removal efficiencies were 90% and 83%, respectively, while in STEP 2, these mean removals were 67% and 72%, respectively. Regarding NTK, in STEP 1 a 98% removal was achieved and in STAGE 2 of 88%. Despite the reduction in process efficiency, the addition of leachate (0.5% v/v) did not compromise the quality of the treated effluent. As regards the emissions of nitrous oxide, the emission fluxes of this gas were slightly lower when the process operated with the addition of leachate. This behavior was contrary to that reported in the literature, probably due to the low concentrations of affluent organic matter observed only during STAGE 2, the higher values of dissolved oxygen and the slightly toxic effect of the leachate on the sludge biomass. In the two phases, the highest emissions were measured at the beginning of the aerobic phase of the SBR, being associated to the production of nitrous oxide during the sedimentation period possibly by the denitrification activity. The masses of N-N2O emitted by the SBR were 82 mg/cycle without leachate and 61 mg/cycle with leachate, so the presence of the leachate did not represent relevance in the emission of this gas.
MEMBROS DA BANCA:
Presidente - 1759225 - ALEXANDRE LIOI NASCENTES
Externo à Instituição - Renato Pereira Ribeiro - IFRJ
Externo à Instituição - Jaime Lopes da Mota Oliveira - FIOCRUZ
Externo à Instituição - Camille Ferreira Mannarino - FIOCRUZ