Biogas purification with biomass ash.

The aim of the study was to investigate the option to purify biogas from small-scale biogas plants by entrapping CO2 and H2S with regionally available biomass ash. Connected to the existing biogas plant Neustift (Tyrol) wood ash placed in a 1 m3 container was used as a trap for CO2 and H2S in the biogas. With the process conditions chosen, for a period of a few hours CO2 was trapped resulting in pure methane. The removal of H2S was much longer-lasting (up to 34 d). The cumulative H2S uptake by the biomass ash ranged from 0.56 to 1.25 kg H2S per ton of ash. The pH of the ash and the leachability of Lead and Barium were reduced by the flushing with biogas, however toxicity towards plants was increased thus reducing the potential of ash use in agriculture. It can be concluded that biomass ash may be used for removal of hydrogen sulphide from biogas in small and medium biogas plants. The economic evaluation, however, indicated that the application of this system is limited by transport distances for the ash and its potential use afterwards.

Morphometric investigations of the pineal gland after ganglionectomy and thyroidectomy under the aspect of circadian and seasonal variations.

It is well established that the pineal gland is involved in the regulation of thyrotropin (TSH) secretion. Previous investigations in our laboratory showed that under hypothyroid conditions the nuclear size of pinealocytes was diminished while an increase in the size of nuclei was seen under hyperthyroid conditions. In the present study we confirmed these results while considering circadian and circannual oscillations. After ganglionectomy (GX, removal of the sympathetic superior cervical ganglia) the mean annual values of the nuclear size of pinealocytes, pineal weights and thyroxine (T4) levels were diminished, whereas the pituitary weights increased. Comparable, but more drastical reactions were found after thyroidectomy (TX). The diminution of the nuclear size of pinealocytes was more pronounced in the wintertime (December, L: D = 8: 16), the finding for the summertime (June, L: D = 16: 8) being similar. Under short-day conditions the nuclear size was larger than under long-day regimes. In the winter the enhancement of the nuclear size was accompanied by decreased pituitary weights and increased T4 levels while under long-day conditions lower size of pinealocytes and T4 levels were associated with higher weights of pituitary glands. The statistically significant circadian patterns of the nuclear size of pinealocytes showed that the largest nuclei occurred at the end of the light phase or at the onset of the dark phase. In June, the largest nuclei were found in the middle of dark (control) or in the early light phase (ganglionectomy). Considering the circadian patterns of pineal weights and T4 levels, these results underline the existence of a functional connection between the pineal gland and the thyroid axis.(ABSTRACT TRUNCATED AT 250 WORDS)