Biofilm development in fixed bed biofilm reactors: experiments and simple models for engineering design purposes.

Biofilm development in a fixed bed biofilm reactor system performing municipal wastewater treatment was monitored aiming at accumulating colonization and maximum biofilm mass data usable in engineering practice for process design purposes. Initially a 6 month experimental period was selected for investigations where the biofilm formation and the performance of the reactors were monitored. The results were analyzed by two methods: for simple, steady-state process design purposes the maximum biofilm mass on carriers versus influent load and a time constant of the biofilm growth were determined, whereas for design approaches using dynamic models a simple biofilm mass prediction model including attachment and detachment mechanisms was selected and fitted to the experimental data. According to a detailed statistical analysis, the collected data have not allowed us to determine both the time constant of biofilm growth and the maximum biofilm mass on carriers at the same time. The observed maximum biofilm mass could be determined with a reasonable error and ranged between 438 gTS/m(2) carrier surface and 843 gTS/m(2), depending on influent load, and hydrodynamic conditions. The parallel analysis of the attachment-detachment model showed that the experimental data set allowed us to determine the attachment rate coefficient which was in the range of 0.05-0.4 m d(-1) depending on influent load and hydrodynamic conditions.

[Pathogenesis of lung changes caused by inhalation of organic solvents]. / Adatok a szerves oldószer inhalációja okozta tüdöelváltozások patogeneziséhez.

Pulmonary lesions were studied in autopsy material and in model experiments by light- and electron microscopy. Histologically in lung severe haemorrhage was found. Electronmicroscopically damage to the permeability could be revealed. Authors assume, that these investigations evidence the hypothesis, according to which inhalation of organic solvents causes morphologically detectable alterations in the lung tissue.

[Various problems concerning maternal mortality during pregnancy]. / A gestatiós anyai halálesetek egyes kérdéseiról

In the autopsy material of the Department of Forensic Medicine of the Semmelweis Medical University--90,000 cases in 25 years (1950-1975)--508 cases of death in the period of gestation have occurred. Author have analysed this material and have established, that in every second case the death occurred due to criminal abortion, in every fifth case due to the complications of the pregnancy and in every third case due to the complications of delivery. By means of trend-calculations it was further established that in the autopsy material of the Department the number of the sudden natural death of women in the reproductive age during the 25 years remained on the same level, but the number of death cases connected with gestation decreased. In the latter group: the number of death cases due to abortion and complications of pregnancy decreased significantly, number of lethal cases due to complications of delivery remained at the same level. Data of the analysis are compared to the data reported in the literature. Some questions--the cause of the death, the criminality when abortions are concerned, questions of the treatment and the responsibility of physicians are also discussed. These investigations seem to evidence that on the base of the evaluation of a large autopsy material the legal medicine can reveal valuable data for the preventive medicine.