Biomedical subjects

J Hahne

Publications and source records attributed to J Hahne.

3 recordsLinked to original sources

PubMed2003

Pre-nitrification by encapsulated nitrifiers--a possibility for self-sufficient energy operation of domestic WWTPs.

The overall energy consumption of domestic wastewater treatment plants (WWTPs) increases with treatment efficiency. Approximately 30 to 45 kWh per people equivalent and year is mostly necessary for advanced nitrogen and phosphorus removal, while the aeration contains the main part of approximately 60%. A new process using encapsulated nitrifiers on gel lens beads is introduced to overcome the high energy consumption of aeration. A more selective nitrification process was found at a nitrification rate of between 50 and 60 mg nitrogen per hour and litre reaction volume corresponding to a hydraulic retention time (HRT) of about 30 to 60 minutes while the soluble Chemical Oxygen Demand (COD) removal could be less than 30% depending on operational conditions of the bio-reactor. The latter enables internal use of wastewater's COD for a post denitrification. For the new process the energy consumption as well as total volume of bio-reactor are much less (approximately 30 to 50% for both) than conventional processes due to the low sludge age for COD and nitrate removal and the avoidance of internal wastewater recycle. Therefore, self-sufficient energy operation of domestic WWTPs operating with advanced treatment efficiency could become possible, if energy recovery by anaerobic sludge digestion is included.

Bioreactors↗

PubMed2003

Advanced nitrogen elimination by encapsulated nitrifiers.

By introducing a mixed population of nitrifiers encapsulated in gel lens beads a more selective nitrification process was found in treatment of settled sewage in lab scale at a hydraulic retention time (HRT) of about 30 to 60 minutes. The reaction rates for oxidation of soluble chemical oxygen demand (SCOD) were found to vary between 25 to 150 mg/L x h while nitrification takes place around 50 mg nitrogen per hour and litre reaction volume. However, based on this SCOD removal in the nitrification step, a consequent post-denitrification process without nitrate recycle and dosage of external carbon sources has been proven to reach substantial nitrate elimination of up to 20 mg nitrogen per litre at COD/N-ratios of approx. 6 in settled sewage. At such COD/N-ratios, suitable nitrogen elimination seems to be possible, because the bioflocs of settled sewage, produced so far by SCOD oxidation and entrapment of particulate COD, are passing through the nitrification process having a substantial contribution to the denitrification rate additionally to the remaining SCOD.

Bioreactors↗

PubMed2001

Equipment availability and diagnostic strategies for suspected pulmonary embolism in Austria.

The aim of this study was to investigate equipment availability and current diagnostic strategies for suspected pulmonary embolism (PE) in Austrian hospitals. A questionnaire was sent to the medical directors of all Austrian hospitals with emergency and/or surgical, orthopedic, and medical departments. The questionnaire contained questions regarding the available equipment suitable for the imaging diagnosis of PE, the first-line and second-line imaging tests for patients with suspected PE, and additional lower extremity venous imaging and laboratory tests that complement the diagnostic armamentarium. The return rate for questionnaires was 81% (127 of 157 hospitals). There were 97% of hospitals that had the equipment to perform sonography, 59% could perform pulmonary angiography, 54% spiral CT, 19% ventilation/perfusion (V/P) scintigraphy, and 4% perfusion scintigraphy alone. Spiral-CT angiography (SCTA) was the first-line imaging study for suspected PE in 56% of hospitals, followed by echocardiography and V/P scintigraphy. Lower extremity venous imaging (47%) and, interestingly, V/P scintigraphy (43%), served as second-line imaging tests. D-dimer tests were included in the diagnostic strategy in 74% of hospitals. Spiral-CT angiography is the most commonly used primary method for suspected PE in Austrian hospitals. The V/P scintigraphy is available only in a minority of hospitals to investigate patients with suspected PE. When V/P scintigraphy is available, however, it is employed in a large number of patients per annum.

Austria↗