Decrease of inhibitory effect of 2-chlorophenol on nitrification in sequencing batch reactors.

The metabolic and kinetic behaviour of a nitrification process in the presence of 2-chlorophenol (2-CP) was evaluated in two sequencing batch reactors (SBR1, SBR2) inoculated with nitrifying sludge previously exposed to phenolic compounds. The SBR1 was inoculated with sludge previously exposed to 2-CP, while the SBR2 was inoculated with sludge previously exposed to p-cresol. An inhibitory effect of 20 mg 2-CP-C/L on both nitrification processes was observed, as specific rates decreased according to a control assay in the absence of 2-CP. However, the inhibitory effect decreased throughout the cycles. At the end of cycle 6, a stable nitrifying process was observed with the sludge previously exposed to 2-CP (SBR1), as an ammonium consumption efficiency and a nitrate production yield close to 99.6 ± 0.3% and 0.99 ± 0.02 were respectively achieved. Despite a complete ammonium consumption being achieved with the sludge previously exposed to p-cresol (SBR2), partial nitrification was observed as nitrate production yield accounted for 0.28 ± 0.08 and nitrite was accumulated within the culture. Nevertheless, both nitrifying sludges had the ability to completely consume 2-CP. The use of SBR systems with nitrifying sludge previously exposed to 2-CP resulted in a better nitrification performance, thus it may be a good alternative for achieving a stable nitrifying respiratory process where complete and simultaneous ammonium and 2-CP consumption can be acquired.

Polysomnographic features in infants with early diagnosis of congenital hypothyroidism.

Thyroid hormones play a major role in the maturation process of the brain. Currently, congenital hypothyroidism is detected by mass screening. The impact of this early hormonal deficiency on the organization of the sleep pattern is not known. In this study, the polysomnographic features in children diagnosed with congenital hypothyroidism were analyzed. Children were detected by mass population screening and the hormonal replacement therapy starts immediately. Children's age ranged between 1.5 and 18 months of age. The duration of hormonal treatment before sleep recordings varied between 8 days and 17 months. Children were polysomnographically recorded in the morning, for at least 2h, obtaining more than one sleep cycle. Results showed a high prevalence of females (5/1) in the group studied. A high proportion of infants (43%) displayed central apnea in different degrees (mild, moderate and severe) as well as hypopnea (83%), mainly in subjects around 4 and 8 months of age. The proportion of infants displaying central apnea decreases as age increases. In addition, indeterminate (light) sleep increase and quiet (slow wave) sleep decrease significantly regardless of age and treatment. The percentage of REM sleep correlated positively with the age of the child at the beginning of the treatment, and negatively with their age at the time of the study. These data indicate that congenital hypothyroidism facilitates the presence of central sleep apnea. The decrease of these respiratory alterations correlates with the increase of the hormonal replacement therapy. It seems that sleep respiratory alterations in congenital hypothyroidism are linked to brain maturation processes in which thyroid hormones play a major role.