Development of instrumentation systems as a base for control of digestion process stability in full-scale agricultural and industrial biogas plants.

This article deals with the analysis of instrumentation from three modern German full-scale biogas plants with different inputs and typical process engineering concepts for German conditions. The measured results from each plant and the suitability of the instrumentation used are evaluated and assessed. Conclusions are also made about improving the use and architecture of the instrumentation. The analysis results show which benefits and optimum combination of on-line and off-line instrumentation could result for the control and automation of industrial and agricultural biogas plants.

Operational results of an agricultural biogas plant equipped with modern instrumentation and automation.

Agricultural biogas plants based on energy crops gain more and more importance because of numerous energetic, environmental and agricultural benefits. In contrast to older biogas plants, the newest generation of biogas plants is equipped with modern ICA equipment and reliable machines/engines. In this paper, the authors present technical details and operational results of a modern full-scale agricultural biogas plant using energy crops.

Microscopic tonsillectomy: a double-blind randomized trial.

OBJECTIVE: To evaluate microsurgical bipolar cautery tonsillectomy (TEmic) by comparing it with traditional blunt dissection tonsillectomy (TEtrad). DESIGN: A double-blind prospective randomized trial with stratification in two age groups. PATIENTS: 200 consecutive patients undergoing tonsillectomy for tonsillar hypertrophy, or recurrent or chronic tonsillitis. OUTCOME MEASURES: Duration of surgery, intraoperative bleeding, daily postoperative pain and otalgia, postoperative bleeding episodes. METHODS: Duration of surgery and operative bleeding were evaluated by the anesthesiologist. The patients were instructed to record daily pain and otalgia. Final postoperative evaluation was done by a different physician, blinded to the surgical technique. RESULTS: Mean intraoperative bleeding was 12 ml for TEmic and 36 ml for TEtrad (P < 0.001). Mean duration of surgery was 37 minutes for TEmic and 36 minutes for TEtrad (NS). Otalgia was present in 41% of TEmic patients and 69% of TEtrad patients (p < 0.001). Daily postoperative pain was lower in the TEmic group than it was in the TEtrad group for the entire study period (10 days). Postoperative hemorrhage was present in three TEmic patients (3%) and in eight TEtrad patients (8%), a difference that did not reach significance (p > 0.1). CONCLUSION: Microsurgical bipolar cautery tonsillectomy compares favorably with traditional techniques in terms of intraoperative bleeding, postoperative pain, otalgia, and hemorrhage. This technique combines the hemostatic advantage of cautery dissection, the excellent visualization achieved by a microscope, and, with the use of a video, greatly improves the physician's ability to teach how to perform a tonsillectomy.