Nutrient and trace element supply in anaerobic digestion plants and effect of trace element application.

To investigate process behaviour and process disturbances in anaerobic digestion (AD) plants, samples of more than 1500 main digesters were taken and concentrations of macro- and micronutrients as well as volatile fatty acids were analyzed. Out of these samples, 600 digesters using energy crops only and 80 digesters using waste substrates were selected to compare the chemical composition as a result of different substrate feeding. High variations in element concentrations were found in both groups. In 60 plants with low micronutrient levels, trace elements were added and process changes were observed. A significant decrease of volatile fatty acids and an increase in digester performance were measured after trace element application. Furthermore, an increase of bacterial biomass could be detected.

New data on temperature optimum and temperature changes in energy crop digesters.

As a result of self-heating in anaerobic digesters when using energy crops in the feedstock, the influence of temperature on the digestion process came back into focus. The aim of this study was to investigate the impact of such temperature increases on process stability. Furthermore, different strategies for the transition from mesophilic to thermophilic conditions and the resulting methane yields at different temperature levels were evaluated. Two main effects were identified with different bio-slurries from agricultural biogas plants: (1) a failure of methane production connected to changes in the microbial community; and (2), a slow but continuous accumulation of propionic acid, though without an immediate effect on methane production. All strategies for increasing the operating temperature showed negative effects on digester performance, some with serious economic consequences for the operator. It was shown that methane yields at different temperature levels in the mesophilic and sub-thermophilic ranges are similar.

Doubling the organic loading rate in the co-digestion of energy crops and manure--a full scale case study.

In the present study the increase of the organic loading rate from 2.11 to 4.25 kg VS m(-3) d(-1) in a two stage, agricultural biogas plant was investigated. The process enhancement resulted in the doubling of the plant capacity from 500 kW to 1000 kW retaining the same digester volume. Efficiency criteria showed good performance throughout the study. At the end of the monitoring, biogas yield was on the same level as before the enhancement, while volume related biogas productivity almost doubled from 1.50 to 2.91 Nm(3) m(-3) d(-1). However, as a consequence of the higher transfer of poorly degraded organic material into the effluent, the residual methane potential of the effluent multiplied by the factor 10. The results of this study show, that most agricultural biogas plants in Austria have a great potential for a significant capacity increase. However, to avoid atmospheric emissions, the effluent storage of high loaded processes has to be integrated into the gas-tight system of the digesters.

The impact of increasing energy crop addition on process performance and residual methane potential in anaerobic digestion.

In a full-scale agricultural biogas plant, the changes in process performance connected with the increasing energy crop addition were monitored. The substrates applied were pig manure, solid energy crops and agricultural residues. During the study, the organic loading rate and the volume-related biogas productivity were doubled to 4.2 kg VS/(m(.3)d) and 2.83 Nm(3)/(m(3).d) respectively, by means of increasing the energy crop ratio in the feedstock to 96.5% (volatile solids). This resulted in an increase of the electrical capacity on a level twice as high as before. At the same time, methane yield and organic degradation rate decreased slightly to 0.35 Nm(3)/kg VS(added) and 87.4%, respectively. The strongest impact observed was on the transfer of partly degraded organic material into the digestate storage and with this, an increase of the residual methane potential of the digestate. A maximum theoretical methane load in the digestate of 14.4% related to total methane production of the biogas plant was observed. This maximum level could be reduced to 5.5%.

Self-heating of anaerobic digesters using energy crops.

With the increasing application of energy crops in agricultural biogas plants and increasing digester volumes, the phenomenon of self-heating in anaerobic digesters appeared in some cases. Until now this development was just known from aerobic systems. To obtain an idea of the thermodynamics inside an anaerobic digester, a detailed analysis of all heat fluxes in a full-scale agricultural biogas plant was carried out. Several experiments were realised to quantify the influences of different internal and external energy sources. To estimate the impact of self-heating in anaerobic systems, data of other full-scale agricultural biogas plants in Austria were collected. Alternatives to the cooling of the digesters are discussed based on individual experiences of several plants. A connection between carbohydrate-rich substrates, especially with high starch contents, and the self-heating could be shown. From the results it can be assumed that the anaerobic digestion of most energy crops is exothermic, which is in contrast to the current thermodynamic belief.

Iodine deficiency in pregnant women in Austria.

BACKGROUND/OBJECTIVES: In Austria, iodine deficiency has been considered to be eliminated owing to table salt fortification with iodine, but whether this also applies to pregnant women is unclear. Even mild iodine deficiency during gestation may lead to neurocognitive sequelae in the offspring. SUBJECTS/METHODS: This is a cross-sectional investigation of urinary iodine excretion in 246 pregnant women (first trimester n=2, second trimester n=53, third trimester n=191, gestational diabetes mellitus n=115, no gestational diabetes mellitus n=131). The iodine content of morning spot urine samples was determined using inductively coupled plasma mass spectrometry. RESULTS: Pregnant women in the Vienna area had a median urinary iodine concentration (UIC) of 87 µg/l. Only 13.8% of the cohort were in the recommended range of 150-249 µg/l, whereas 21.5% had a UIC of 0-49 µg/l, 40.2% had a UIC of 50-99 µg/l and 19.5% had a UIC of 100-149 µg/l. In all, 4.9% had a UIC over 250 µg/l. A total of 137 women of foreign origin had a significantly higher iodine excretion compared with Austrian-born women. Maternal or gestational age had no influence on UIC. Although 79 women on iodine supplementation had a significantly higher iodine concentration compared with women without iodine supplementation (97.3 vs 80.1 µg/l, P=0,006), their UIC was below the recommended range, indicating that doses of 100-150 µg per day are not sufficient to normalize iodine excretion. Sodium and iodine concentrations in the urine were tightly correlated (R=0.539, n=61), suggesting that low intake of iodized salt might contribute to insufficient iodine supply. CONCLUSIONS: This study shows that pregnant women in the Vienna area have a potentially clinically significant iodine deficiency and that currently recommended doses of iodine supplementation may not be sufficient.

[Teeth as prostheses materials for reconstruction of disrupted ossicular chain]. / Zähne als Prothesenmaterial zur Rekonstruktion der zerstörten Ossikelkette.

Since 1988 we have routinely used prostheses made from teeth for ossicular reconstruction and have now done more than 400 implants. Short-time results with at least 1 year implantation were studied in a retrospective analysis of 319 cases with a review of 88 patients. Eighty percent of the implants were covered by an intact tympanic membrane, while in 10% the prosthesis was completely uncovered. This apparent perforation was not due to a material-related extrusion, but was caused by persistent ventilation dysfunction of the middle ear. This was associated with a progressive retraction of the tympanic membrane, which could be seen in all of these cases. The overall acoustic results were disappointing and hearing gain was only 8.7 dB. However, these results were due to the unsolved problems of chronic middle ear inflammation and were not influenced by the dental material. We have been very satisfied with the teeth as implant material, as they can be autoclaved (eliminating problems due to infection) without any loss of mechanical strength. Furthermore, their practically cost-free production has a definite financial advantage over the expensive, commercially-available implants. The prostheses can be sculptured by the young resident during his otologic training, with this experience then resulting in better and faster tympanoplasties.

Headache caused by a sphenoid mucocele but presenting as an ergotamine-induced headache.

In a 65-year-old woman, symptomatic headache caused by a mucocele of the sphenoid sinus led to ergotamine abuse and subsequent ergotamine-induced headache. Since there were no neurological symptoms initially and the patient previously suffered from migraine, the mucocele was not recognized. Only after unsuccessful drug withdrawal therapy and an MRI, was the correct diagnosis made. Surgical removal of the mucocele led to complete relief of headache within 3 weeks. We conclude that ergotamine-induced headache can develop on the basis of symptomatic headache. In spite of the effectiveness of ergotamine tartrate, an MRI should be performed if focal neurological symptoms occur.

The nervus terminalis also exists in cyclostomes and birds.

The terminal nerve has been described in all vertebrate classes, with the exception of cyclostomes and birds. With regard to this question, we have examined representatives of these two classes using tracer techniques, and found a terminal nerve in larval lampreys and young domestic mallards. Horseradish peroxidase or cobaltous lysine was injected into the olfactory mucosa, which is known to be innervated by peripheral branches of the terminal nerve. The brains were then searched for labeled, centrally directed fibers of the terminal nerve that project further caudally than the glomerular layer of the olfactory bulb. In larval lampreys, centrally projecting fibers of the terminal nerve were found in the tel-, di- and mesencephalon. Termination of labeled fibers was observed in the hypothalamus. Some fibers of the terminal nerve cross to the contralateral side via the commissure of the posterior tuberculum. In young ducks, the terminal nerve projects ipsilaterally along the medial edge of the telencephalon.