Remoción de Percloroetileno en dos Tipos De Sistemas Anaerobios Continuos

Performance was evaluated and compared in two lab-scale mesophilic methanogenic complete mix reactors (RMC1, RMC2) and a methanogenic fluidized bed reactor (RANLEF) for removal of perchloroethylene (PCE) when fed a moderate concentration of methanol The RMCs and RANLEF were operated at loading rates of 0.07 and 1gCOD·l ^-1·d ^-1, and hydraulic retention times of 15 and 1 day, respectively. The experimental design consisted of three periods of operation: methanogenic regime with methanol as carbon source (1): same with acclimation to 20 (2.1) or 40mgPCE·l ^-1 (2.2); and same with 40mgPCE·l ^-1 in RANLEF and RMC1 and 20 mgPCE·l ^-1 in RMC2 (3). In the first period both PCE and COD removals were higher in RANLEF; biogas CH ₄ content and chloride increase were similar in the three reactors. During period 2.2, PCE removal increased up, to 81% in RANLEF, suggesting a good acclimation to the higher inflow PCE concentration; COD reduction remained high, and CH ₄ in biogas indicated a satisfactory methanogenic regime. The RMCs experienced drastic performance impairments upon increase of inflow PCE (20 to 40mg·l ^-1), and RMC1 was returned to operate with 20mgPCE·l ^-1. RMC2 performance remained poor, showing a drastic deterioration of methanogenesis and PCE removal. By contrast, RMC1 with 20mgPCE·l ^-1 re-covered from the negative transient state and exhibited similar performance to that of RANLEF fed 40mg·l ^-1. In period 3, RANLEF with 40mg·l ^-1 and RMC1 with 20mg·l ^-1 showed similar performances, whereas RMC2 kept with 40mg·l ^-1 exhibited impaired COD removal, lower biogas productivity and CH ₄ biogas content, but a PCE removal very close to RANLEF and RMC1. The dehalogenation efficiency of RMC2 was significantly lower than that of the RANLEF, which appears to be a more robust and stable anaerobic process for the effective removal of high concentrations of PCE.