Influência da granulometria e do pH no processo de dessorção de amônia em torres de recheio

Abstract

In Brazil are generated daily approximately 201,000 tons of municipal solid waste. The quantity collected, it is estimated that 58% are landfilled. The degradation of the organic fraction of solid waste, in combination with the percolation of rainwater leads to the generation of a liquid known as leachate. This liquid is very contaminant because present a high concentration of ammonia nitrogen that cause environmental impacts, when discharged in a receiving body without treatment. The desorption process of ammonia is presented as an alternative to removing ammonia nitrogen from landfill leachate by mass transfer from the liquid phase to the gas phase. Given the above, this study aims to evaluate the influence of particle size of the filling and pH of the leachate in the desorption process of ammonia in tower, applying three particle sizes of crushed stone for the filling in the tower and also three different fixes pH for the landfill leachate. The grain size of the gravel used in the study were: nº25, nº19 and nº12,5 and the pH of the leachate used was adjusted to 9, 10 and 11. The experimental system was developed at the Experimental Station for Biological Treatment of Sewage (EXTRABES) belonging to the State University of Paraiba in Campina Grande - PB, consisting of three stuffing tower and a reactor for receiving the ammonia gas. The leachate used for the feeding of the towers was collected on metropolitan landfill of the city of João Pessoa, capital of Paraíba state, and presented during the study the ammonia concentration of 2.370 mgN.L . The parameters monitored were: pH, ammonia nitrogen, total alkalinity, volatile fatty acid, COD Total and COD . The application of desorption process to reduce the concentration of ammonia nitrogen in landfill leachate showed removal efficiency between 92.2% and 93.7%, removal efficiency was between 33.0 % and 41.0% for COD Total Filtered . Operating time ranging from 5 hours to 1 hour and 40 minutes. The process efficiency was directly proportional to the pH of the leachate and the granulometry of the stuffing used in the tower during the desorption process. The greater the amount of correction of the pH of the leachate and smaller particle size of the stuffing of the tower, higher efficiency was observed during the process. Thus, the desorption process of ammonia stuffing tower is presented as an efficient alternative for removal of ammonia in landfill leachate, however it is noteworthy that it requires posttreatment.