Dessorção de nitrogênio amoniacal de lixiviado de aterro sanitário em reatores de fluxo pistonado

Abstract

The landfill is the most widely used method for disposal of municipal solid waste, due it be technically feasible (COTMAN and GOTVAJN, 2010). After landfilled, the solids wastes suffer physical, chemical and biological alterations. The degradation of biodegradable organic fraction, combined with percolation of rainwater leads to the generation of a highly contaminated liquid called leachate (KURNIAWAN, et al., 2006a). The treatment of leachate from landfill is an important issue in the management system of urban solid waste, due the leachate present a high concentration of ammonia nitrogen that cause environmental impacts, when discharged in a receiving body without treatment (Kim et al. 2007). The desorption process of ammonia is presented as an alternative to removing ammonia nitrogen from landfill leachate (QUAN et al., 2009). Therefore, the present research aims to evaluate the desorption process of ammonia in landfill leachate using reactors with piston flow, applying surface load of 650 kg NH 4 +.day-1ha-1 (phase 1), 750 kg NH4 +.day-1ha-1 (phase 2) nd 850 kg NH4 +.day-1ha-1 (phase 3) and HRT of 51.2 days, 64.9 days and 55,6 days, respectively. The experimental system was developed at the Experimental Station for Biological Treatment of Sewage (EXTRABES) belonging to UEPB in Campina Grande - PB. The experiment consisted of the monitoring of 04 reactors in series with piston flow. These reactors were fed with leachate, in natura, collected and transported from the landfill of the city of João Pessoa PB, without forced feeding air and without pH correction. The parameters monitored were: pH, ammonia nitrogen, total alkalinity, volatile fatty acids, total and soluble COD and volatile solids, according to the APHA (2005). The application of the desorption process for the reduction of the ammonia nitrogen concentration in leachate from sanitary landfill had removal efficiency of 99.01% in step 1, 99.3% in stage 2 and 99.5% in stage 3, regarding the concentration of total COD the removal efficiency was 69.2%, 40.12% and 29.23% in steps 1, 2 and 3. With the kinetic study was observed that the extent that the increased surface load, it was obtained more efficient removal of the ammonia nitrogen concentration and lower efficiency of removal of total COD concentration. The cost estimated for removal of ammonia nitrogen by the desorption process of ammonia in reactors with piston flow to the surface load 850 kg NH4 +.ha-1.d-1 was R$ 1.47/kgN.d-1 in the leachate from the landfill of the city of João Pessoa - PB. This study showed that is not necessary to use the reactor R4, reducing the cost of treating the leachate at 21.67% for this surface load. Thus, the desorption process of ammonia presents as a viable alternative for removal of ammonia in landfill leachate, however it is emphasized that it requires posttreatment.