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Biomedical subjects

J Meinhold

Publications and source records attributed to J Meinhold.

At least 19 recordsLinked to original sources
PubMed2006

Modelling of wastewater treatment plants--how far shall we go with sophisticated modelling tools?

Several levels of complexity are available for modelling of wastewater treatment plants. Modelling local effects rely on computational fluid dynamics (CFD) approaches whereas activated sludge models (ASM) represent the global methodology. By applying both modelling approaches to pilot plant and full scale systems, this paper evaluates the value of each method and especially their potential combination. Model structure identification for ASM is discussed based on a full-scale closed loop oxidation ditch modelling. It is illustrated how and for what circumstances information obtained via CFD (computational fluid dynamics) analysis, residence time distribution (RTD) and other experimental means can be used. Furthermore, CFD analysis of the multiphase flow mechanisms is employed to obtain a correct description of the oxygenation capacity of the system studied, including an easy implementation of this information in the classical ASM modelling (e.g. oxygen transfer). The combination of CFD and activated sludge modelling of wastewater treatment processes is applied to three reactor configurations, a perfectly mixed reactor, a pilot scale activated sludge basin (ASB) and a real scale ASB. The application of the biological models to the CFD model is validated against experimentation for the pilot scale ASB and against a classical global ASM model response. A first step in the evaluation of the potential of the combined CFD-ASM model is performed using a full scale oxidation ditch system as testing scenario.

Models, Theoretical↗
PubMed2006

Aeration control for simultaneous nitrification-denitrification in a biological aerated filter using internal model approach.

Experience has shown that simultaneous nitrification/denitrification in a biological aerated filter is possible. However these systems react very sensitively to the aeration control strategies applied. Poorly adapted control strategies induce a strong decrease in treatment efficiency. A new control strategy for simultaneous N/DN is developed. The strategy proposed makes use of ammonia measurements and the inlet and outlet: a Feedback/Feedforward block. Passing by a calculation of the load to be eliminated, an estimation of the air flow velocity to be applied is carried out dynamically. A retroactive loop corrects this prediction in order to reach exactly the desired set point. This control approach has been implemented and tested at pilot plant scale for a period of 18 months. The pilot plant consists of two coupled BAF cells, reflecting closely industrial scale situations. Comparative studies reveal clearly the improved performance of the developed FF/FB control strategy compared to classical controllers. The benefits include 5% increase in nitrogen removal performance and a reduction of 15 to 20% in air requirement, offering a rapid return of investment costs.

Algorithms↗
PubMed2005

Aerobic granulation in a sequencing batch reactor (SBR) for industrial wastewater treatment.

Aerobic granulation seems to be an a attractive process for COD removal from industrial wastewater, characterised by a high content of soluble organic compounds. In order to evaluate the practical aspects of the process, comparative experimental tests are performed on synthetic and on industrial wastewater, originating from pharmaceutical industry. Two pilot plants are operated as sequencing batch bubble columns. Focus was put on the feasibility of the process for high COD removal and on its operational procedure. For both wastewaters, a rapid formation of aerobic granules is observed along with a high COD removal rate. Granule characteristics are quite similar with respect to the two types of wastewater. It seems that filamentous bacteria are part of the granule structure and that phosphorus precipitation can play an important role in granule formation. For both wastewaters similar removal performances for dissolved biodegradable COD are observed (> 95%). However, a relatively high concentration of suspended solids in the outlet deteriorates the performance with regard to total COD removal. Biomass detachment seems to play a non-negligible role in the current set-up. After a stable operational phase the variation of the pharmaceutical wastewater caused a destabilisation and loss of the granules, despite the control for balanced nutrient supply. The first results with real industrial wastewater demonstrate the feasibility of this innovative process. However, special attention has to be paid to the critical aspects such as granule stability as well as the economic competitiveness, which both will need further investigation and evaluation.

Aerobiosis↗
PubMed1998

Electrocardiographic changes during insulin-induced hypoglycemia in healthy subjects.

Hypoglycemia is associated with alterations of the ECG, a phenomenon which might be used for the development of a hypoglycemia detection device. We investigated the reproducibility and magnitude of ECG alterations during insulin-induced hypoglycemia in nine healthy volunteers. The subjects were studied twice with an identical study protocol on two different study days. During hypoglycemia frequent ECG recordings were done with a conventional 12 lead ECG. S.c. injection of 0.15 U/kg of regular insulin induced a fourfold increase in insulinemia on both study days as well as a mean decline in blood glucose by 1.6 mmol/l to a minimum of 2.8 mmol/l within 60 min after injection. Blood potassium levels declined by a mean of 0.25 mmol/l to minimal values of 3.69 mmol/l. On both study days, a progressive flattening of the T-waves was observed during the experiments. R-waves remained constant leading to an increase in RT ratios by at least 50% in comparison to baseline values. These changes were most pronounced in leads I, V3, V5 and V6. The magnitude and reproducibility of the observed ECG changes during hypoglycemia may allow the development of a hypoglycemia detection device.

Adult↗
PubMed1983

[Experiences with intranasal and parenteral use of 1-desamino-8-D-arginine vasopressin (DDAVP). Use in the diagnosis of hypophyseal function].

While 1-desamino-8-D-arginine-vasopressin is not suitable for the functional diagnostics of the anterior pituitary gland, it has as in the therapy of the central diabetes insipidus a firm place also in its diagnostics. A hypothalamic neurohypophyseal system was demonstrated. Apart from a secure diagnostic evidence the test shows further advantages in comparison to the hitherto performed methods: an essentially smaller load for patient and personnel, a shorter duration and a simplified performance. First findings in patients with central diabetes insipidus, in a female patient with renal diabetes insipidus and patient without disturbance of the water balance are discussed. A control of our findings in other institutions is desirable.

Administration, Intranasal↗
PubMed1983

[Experiences with the intranasal and parenteral use of 1-desamino-8-D-arginine vasopressin (DDAVP)--effect of one time parenteral and intranasal applications].

The balance examinations in 10 patients with a neurohypophyseal diabetes insipidus under various forms of parenteral application (s.c., i.m., i.v.) of the 1-desamino-8-D-arginine-vasopressin show universally the very good antidiuretic effect also under these conditions. Identically with the course of action after intravenous application the maximum of action as obtained after 1 to 2 hours, the duration of action depends on the dosage, in parenteral application of 1 microgram 18 to 24 hours, on an average 20 hours. According to the results demonstrated there are no references to a specific influence of the excretion of sodium, potassium and urea. The particular dynamics of the excretion rates of these substances, of the osmolarity clearance and the osmolarity of the urine is the sequel of the restitution of the renal concentration ability under the application of the antidiuretic hormone.

Administration, Intranasal↗
PubMed1982

[Long-term study in congenital refractory anemia and secondary siderosis].

It is reported on the course of the disease in a female patient with congenital therapy-refractory anaemia, in whom a transfusion siderosis of high degree with functional disturbances of the myocardium and the liver, with endocrine disturbances (primary hypothyroidism and normogonadotropic hypogonadism) and with small growth became clinically manifest. A reduction of the iron overload by a continuous desferrioxamine therapy in form of long-term subcutaneous infusions over two years could be proved. Possibilities and problems of treatment and conclusions relevant to practice are described.

Adolescent↗
PubMed1978

[Renal potassium-loss syndrome as origin of extreme hypokalemia].

Case report on a 35-year-old female patient with life-threatening respiratory insufficiency in extreme hypopotassemia with unclear genesis. A simultaneously existing systemic acidosis and alkaline urine render a secondary tubular acidosis as a sequel of a symptom-poor chronic pyelonephritis probable. Ascertainment by ammonium chloride load. Discussion of the most essential causes of a hypotassemia and emphasizing of a consequent antibiotic sanation also of asymptomatic bacteriurias. It is referred to the necessity of a highly dosed long-term potassium substitution.

Acidosis, Renal Tubular↗
PubMed1976

[Increased insulin-sensitivity as a 1st indication of Addison's disease in a juvenile diabetic patient].

Case report on a 25-year-old patient with diabetes mellitus which is difficult to be controlled. Relapsing vomitting, loss of body-weight, retention of substances normally contained in the urine, hyperpotassaemia, hypernatraemia as well as an increased insulin sensitivity render an additionally existing morbus Addison probable. Confirmation by means of the determination of the Porter-Silver chromogenes. It is referred to the apparantly frequently not understood syntropy in diabetes mellitus and Addison's disease. An autoimmunological process is discussed.

Addison Disease↗