CFD-based process optimization of a dissolved air flotation system for drinking water production

Dissolved air flotation (DAF) has received more attention recently as a separation technique in both drinking water as well as wastewater treatment. However, the process as well as the preceding flocculation step is complex and not completely understood. Given the multiphase nature of the process, fluid dynamics studies are important to understand and optimize the DAF system in terms of operation and design. The present study is intended towards a comprehensive computational analysis for design optimization of the treatment plant in Kluizen, Belgium. Setting up the modelling framework involving the multiphase flow problem is briefly discussed. 3D numerical simulations on a scaled down model of the DAF design were analysed. The flow features give better confidence, but the flocs escape through the outlet still prevails which is averse to the system performance. In order to improve the performance and ease of maintenance, design modifications have been proposed by using a perforated tube for water extraction and are found to be satisfactory. The discussion is further reinforced through validating the numerical model against the experimental findings for stratified flow conditions

Prophylactic Use of Alfacalcidol in Corticosteroid-Induced Osteoporosis

One hundred and forty-five patients suffering from diseases requiring long-term treatment with high doses of corticosteroids (30 mg/day or greater of prednisolone) were recruited to the study. Patients had to be steroid naive on entry to the study (not more than 15 days of treatment with a corticosteroid within the previous 24 months). Patients were randomized to receive either 1 microgram/day alfacalcidol or placebo capsules for 12 months. Bone mineral density (BMD) of the lumbar spine was assessed by dual-photon absorptiometry on entry and after 3, 6 and 12 months' treatment. Safety was monitored by the recording of all adverse events reported by patients and the regular screening of blood samples for hematology and serum biochemistry. Of the 145 patients, 74 were randomized to alfacalcidol and 71 to placebo. The treatment groups were well matched at baseline with no significant differences in demographic, clinical or biochemical parameters. The mean equivalent dose of prednisolone at baseline was 46.6 mg/day and 46.3 mg/day for the alfacalcidol and placebo group respectively. From the 145 patients randomized to treatment, 71 (38 who received alfacalcidol and 33 who received placebo) provided BMD data both at baseline and at 3, 6 and 12 months. The percentage change in BMD after 6 months' treatment was -2.11% in the alfacalcidol group and -4.00% in the placebo group (p = 0.39). After 12 months the percentage change in BMD was +0.39% (CI: -4.28 to 4.81) in the alfacalcidol group and -5.67% (CI: -8.13 to -3.21) in the placebo group, this difference (6.06%, CI: 0.88 to 11.24) being statistically significant (p = 0.02). An intention to treat analysis also showed a significant difference between the two treatment groups in alfacalcidol's favor (3.81%, p = 0.01; CI: 0.92 to 6.70). There was no significant difference between the two treatment groups in the corticosteroid dose at any time point during the study. Serum calcium was measured throughout and there were no significant differences between the two treatment groups at any visit. This study suggests that alfacalcidol can prevent corticosteroid-induced bone loss from the lumbar spine. Long-term use of alfacalcidol was not associated with any significant adverse effects in this diverse group of patients

Effects of sugars and aminooxyacetic acid on the longevity of pollinated Oncidium Gower Ramsey flowers

The effects of sugars and aminooxyacetic acid (AOA) on the vase life of pollinated Oncidium Gower Ramsey flowers were investigated in this study. AOA was found to be an effective ethylene inhibitor as holding solutions containing 0.5 mM of AOA considerably prolonged the vase life of the flowers. The best treatment in delaying the senescence of pollinated Oncidium Gower Ramsey flowers were solutions of 4 sucrose + 0.5 mM AOA and 0.5 mM AOA. Both these treatments managed to delay the discolouration, furrowing and appearance of the veins up to nearly twice the length of time it took for the control flowers held in distilled water, to start senescing. The addition of glucose to the holding solution was not as effective as sucrose in delaying the senescence and prolonging the vase life of the flowers. Signs of senescence such as discolouration were measured using the Minolta chroma meter. Weight loss and pH of the holding solutions were also measured daily. AOA added in the solutions had a positive effect of lowering the pH of the holding solution thus inhibiting bacterial growth in the vial. A low pH also accounted for better water uptake by the flowers which delayed turgor loss and thus also delaying the wilting of the flowers