Aplicação do reator de chicanas no tratamento de lixiviados de aterros sanitários de resíduos sólidos urbanos para remoção de nitrogênio amoniacal por “stripping”

Abstract

The ammoniacal nitrogen (AN) from landfill leachates (LL) may cause severe impacts on the environment and public health if disposal at concentrations above 2000 mg/L. The stripping process is one of the methods worldwide used and technically outstanding among the alternatives for AN removal from leachates. The study of physical treatment process for removal of ammonia from the leachate in a landfill in São Leopoldo/RS was the objective of this work. The study was developed through batch tests in a baffle reactor (BR) that was previous by bench tests using the jar test. The variables tested to monitor the experiment were: initial concentration of AN and leachate recirculation flow. Samplings and physicochemical analyses of the following parameters were performed: pH, COD, temperature, nitrogen series, solids series, alkalinity, nitrite and nitrate to verify system efficiency. None of the assays was realized changes in pH and/or temperature in leachate. The hydraulic detention time (HDT) of 12 days resulted in AN removal ranging from 27% to 52%. However, this is not sufficient to comply with the national legislative standards of effluent emission into water resources. Statistically the “temperature” parameter showed influence on AN removal and greater removals were obtained for ambient temperatures above 20ºC. For the evaluated conditions was conclude that the best technical-enviromental option for treatment of LL is the leachate recirculation flow of 1.7 m³/h at temperatures higher than 20ºC. On the other hand, for temperatures below 20ºC the best BR performance occurred with leachate recirculation flow of 0.0 m³/h (without pump). This represents a reduction of energy consumes but is necessary an increase of HDT. According to the results obtained, the BR is a technically feasible option to treat LL as a physical process to remove ammonia by stripping and it may be indicated as a pre-treatment before biological systems.