Evaluation of methylparaben removal and microbial behavior using a SBR system/Remocion de methilparabeno y comportamiento microbiano de un sistema SBR

We evaluated the variation in microbial populations and the behavior of an SBR system in the removal of methylparaben (MePB). The experimentation was carried out for 14 weeks, in three operational stages as follows: stabilization (Stage I), (Stage II = 300 [micro]gMePB/L and Stage III = 600 [micro]gMePB/L). The variation of the microorganisms was analyzed over the experimentation time along with the contact with the pollutant to be degraded, and the removal percentage of COD and MePB, with results of 88 [+ or -] 5,5% and 92 [+ or -] 7,7% respectively. Kinetic of MePB removal was evaluated to obtain the rate constant of biological degradation, [K.sub.biol]. Using these kinetic results, the effect of different concentrations of MePB and biomass on biodegradation behavior was evaluated. [K.sub.biol] ([LgSS.sup.-1][d.sup.-1]) values were obtained of 42.8 and 79 respectively; and 472 [+ or -] 38.0 [micro]gMePB/L, at biomass contents of 1466.7 and 2666.7 mgSSV/L, where [K.sub.biol] ([LgSS.sup.-1] [d.sup.-1]) values were obtained of 11.0 and 32.6 respectively. The variation of the microbial populations were analyzed using DGGE. The results obtained indicated that the populations presented similar characteristics between the stages. However, for the biomass samples of Stage I and stage III, significant differences were identified in the composition of microbial populations. Nonetheless, this did not affect the removal of MePB and the diversity conditions that characterize an aerobic system. KEYWORDS: Water treatment, water pollution, microbial populations Se evaluo la variacion en las poblaciones microbianas y el comportamiento de un sistema SBR en la eliminacion de metilparabeno (MePB). La experimentacion se llevo a cabo en tres etapas: (Etapa I: aclimatacion), (Etapa II = 300 [micro]gMePB/L y Etapa III = 600 [micro]gMePB / L). La variacion de los microorganismos se analizo durante el tiempo de experimentacion junto con el contacto con MePB y el porcentaje de eliminacion de DQO, con resultados de 88 [+ or -] 5,5% y 92 [+ or -] 7,7% respectivamente. Se evaluo la eliminacion cinetica de MePB para obtener la constante de velocidad de degradacion biologica, [K.sub.biol]. Usando estos resultados cineticos, se evaluo el efecto de diferentes concentraciones de MePB y biomasa en el comportamiento de la biodegradacion. Se obtuvieron valores de [K.sub.biol] ([LgSS.sup.-1][d.sup.-1]) de 42.8 y 79 respectivamente; y 472 [+ or -] 38.0 [micro]gMePB / L, a contenidos de biomasa