Improving aeration systems in saline water (part II): effect of different salts and diffuser type on oxygen transfer of fine-bubble aeration systems.

The objective of the present study is to investigate the different effects on the oxygen transfer of fine-bubble aeration systems in saline water. Compared to tap water, oxygen transfer increases due to the inhibition of bubble coalescence. In Part I of the present study, we investigated in laboratory-scale experiments the effect of design of diffuser membrane. The objective of Part II is the assessment of effects of different salts, diffuser type and diffuser density. We measured the concentration of various salts (MgCl2; CaCl2; Na2SO4; NaCl; KCl) above which coalescence is fully inhibited and oxygen transfer reaches its maximum (referred to as the critical coalescence concentration; CCC). For this purpose, we developed a new analytical approach, which enables investigation of the coalescence behaviour of any aeration system and (mixed) salt solution quickly and easily by evaluating the results of oxygen transfer tests. To investigate the transferability to large scale and the effect of diffuser type and density, we repeated lab-scale experiments in a 17,100 L pilot-scale test tank and carried out additional tests with tube and plate diffusers at different diffuser densities. The results show that despite the higher pressure drop, diffusers with dense slit density and smaller slits are to be recommended in order to improve efficiency of aeration systems in saline water.

Fouling mitigation in anaerobic membrane bioreactors using fluidized resin beads.

This study focuses on the use of fluidized resin beads to mitigate fouling during ultrafiltration (UF) of the effluent of an anaerobic bioreactor. Two different module configurations were tested: A fluidized bed of resin beads was generated in a tubular UF membrane, and a hollow fiber (HF) UF membrane was submerged into a fluidized bed, respectively. During filtration of anaerobically treated synthetic wastewater using the tubular module, fluidized resin beads with a diameter of 0.5-0.71 mm did not show any beneficial effect. In contrast, the presence of fluidized resin beads (diameter of 0.5-0.71 and 1.00-1.25 mm) in the HF module reduced the fouling rate significantly. Furthermore, particle diameter and the bed voidage affected the cleaning efficiency of a pre-fouled membrane in the HF module. Interestingly, short-term filtration tests (<2 h) of a dextran solution showed that fluidized resin beads are able to minimize concentration polarization of a macromolecule, even in the tubular module. Therefore, it is supposed that fouling of the anaerobically treated synthetic wastewater was mainly attributed to the deposition of colloidal and particulate matter.

Fluidized glass beads reduce fouling in a novel anaerobic membrane bioreactor.

This study focuses on the use of fluidized glass beads as turbulence promoters in a laboratory-scale anaerobic membrane bioreactor treating municipal wastewater at 20 °C. The addition of fluidized glass beads into an external tubular ceramic membrane enabled the operation at low crossflow velocities of 0.053-0.073 m/s (mean fluxes between 5.5 and 9.7 L/(m2·h)) with runtimes >300 h. Glass beads with a diameter of 1.5 mm were more effective than smaller ones with a diameter of 0.8-1.2 mm. Increasing the bed voidage from 74 to 80% did not show any beneficial effect. As scanning electron microscope examination showed, the fluidized glass beads damaged the used membrane by abrasion. The overall total chemical oxygen demand (COD) removal was between 77 and 83%, although mean hydraulic retention times were only between 1.3 and 2.3 h. The production of total methane was increased about 30% in comparison to the bioreactor without membrane. The increased methane production is presumably attributed to biological conversion of rejected, dissolved and particulate organic matter. The total required electrical energy was predicted to be about 0.3 kWh/m3.

Electrochemical oxidation of refractory compounds from hydrothermal carbonization process waters.

Hydrothermal carbonization (HTC) is an emerging technology for treating sewage sludge. However, the resulting HTC process water is heavily contaminated with various carbonaceous and nitrogenous components, some of them being non-biodegradable. To implement HTC as a full-scale treatment alternative for sewage sludge, effective concepts for treating process water are crucial. This study focuses on the electrochemical oxidation (EO) using a boron-doped diamond electrode to treat one HTC process waters with different pretreatments: (i) without pretreatment, (ii) biologically pretreated with chemical oxygen demand (COD) removal, (iii) biologically pretreated with nitrification and denitrification. The EO removed COD of all HTC process waters by over 97%, but as COD concentrations decreased, the instantaneous current efficiency (ICE) dropped below 5% and energy consumption increased. The organically bound and refractory nitrogen was completely mineralized and converted to mainly NO3-N. After EO of process waters without nitrification/denitrification, nitrogen was present as NO3-N with up to 730 mg/L and NH4-N with up to 1813 mg/L. Such high ammonium concentrations treatment could be interesting for nitrogen recovery. In addition, the toxicity towards Vibrio fischeri could be reduced to a large extent. The findings suggest that EO after a biological step with COD removal is a viable solution for HTC process water treatment.

Impact of benzalkonium chloride on anaerobic granules and its long-term effects on reactor performance.

This study assessed the inhibitory and performance-degrading effects induced by the cationic surfactant benzalkonium chloride (BAC) on anaerobic granules during the long-term operation of a laboratory-scale expanded granular sludge bed (EGSB) reactor. To address the critical scientific problem of how BAC affects the efficiency of EGSB reactors, this research uniquely evaluated the long-term stress response to BAC by systematically comparing continuous and discontinuous inhibitor exposure scenarios. The novel comparison demonstrated that inhibitor concentration is of minor relevance compared to the biomass-specific cumulative inhibitor load in the reactor. After exceeding a critical biomass-specific cumulative inhibitor load of 6.1-6.5 mg BAC/g VS, continuous and discontinuous exposure to BAC caused comparable significant deterioration in reactor performance, including accumulation of volatile fatty acids (VFA), decreased removal efficiency, reduced methane production, as well as the wash-out, flotation, and disintegration of anaerobic granules. BAC exposures had a more detrimental effect on methanogenesis than on acidogenesis. Moreover, long-term stress by BAC led to an inhibition of protein production, resulting in a decreased protein-to-polysaccharide ratio of extracellular polymeric substances (EPS) that promoted destabilizing effects on the granules. Finally, hydrogenotrophic methanogenesis was triggered. Reactor performance could not be restored due to the severe loss of granular sludge.

Dynamic alpha factor prediction with operating data - a machine learning approach to model oxygen transfer dynamics in activated sludge.

Aeration is an energy-intensive process of aerobic biological wastewater treatment. An accurate model of oxygen transfer dynamics in activated sludge tanks would improve design and operation of aeration systems. Such a model should consider spatial and diurnal variation of α-factor as well as site-specific conditions that impact oxygen transfer. For this dynamic prediction a machine learning approach was used for the first time. The data-driven method was based on long-term ex-situ off-gas measurements with pilot-scale reactors (5.8 m height, 8.3 m3 vol) coupled to full-scale activated sludge tanks on the sites of two conventional and a two-stage activated sludge treatment plant. The ex-situ off-gas method allowed to quantify theoretical off-gas parameters in non-aerated zones and thus consider the whole activated sludge tank. We introduced the α0-factor to compare aerated and non-aerated zones under nonsteady-state conditions. Like the established α-factor for steady-state conditions, the α0-factor describes oxygen transfer inhibiting effects in activated sludge. α0-factor was lowest in upstream denitrification zones. This indicates an anoxic elimination of oxygen transfer inhibiting wastewater contaminants which improved oxygen transfer in subsequent aerobic zones. Random Forest models predicted α0-factor reliably in all examined activated sludge tanks even for stormwater events and seasonal variation. Model development only required online sensor data already available to operators. Our results suggest that machine learning models can dynamically predict α-factors in a variety of activated sludge processes, thus considering site-specific conditions in model training without manual calibration.

[Resuscitative endovascular balloon occlusion of the aorta (REBOA) : Current aspects of material, indications and limits: an overview]. / "Resuscitative endovascular balloon occlusion of the aorta" (REBOA) : Aktuelles zu Material, Indikationen und Grenzen: ein Überblick.

BACKGROUND: Resuscitative endovascular balloon occlusion of the aorta (REBOA) describes an endovascular procedure in which a blocking balloon is introduced into the aorta to reduce bleeding situated distal to the balloon and simultaneously to improve cardiac and cerebral oxygenation. OBJECTIVE: Presentation of the REBOA technique, the possible indications, the required material and possible complications of the procedure. MATERIAL AND METHODS: Non-systematic review of the currently available literature. RESULTS: The REBOA procedure is an adjunct to achieve hemodynamic stabilization in patients with traumatic hemorrhage and ruptured aortic aneurysms. The complication rate of the procedure is approximately 5%, whereby access complications are the most common; however, fatal complications are also possible. CONCLUSION: A balloon block of the aorta is well established in the treatment of ruptured aortic aneurysms. There is growing evidence that REBOA is a minimally invasive alternative to open surgical cross-clamping of the aorta by thoracotomy for the treatment of patients with polytrauma and hemorrhagic shock due to abdominal or visceral bleeding. Due to the development of new balloon catheters, which can be placed without stiff guidewires and require smaller sheath diameters, REBOA is also discussed for treatment of postoperative abdominal or gynecological bleeding or as a possible adjunct to cardiopulmonary resuscitation for nontraumatic cardiac arrest.

An open-label pilot study of infliximab therapy in diffuse cutaneous systemic sclerosis.

AIM: The safety and potential efficacy of a chimaeric anti-tumour necrosis factor alpha monoclonal antibody (infliximab) were examined in diffuse cutaneous systemic sclerosis (dcSSc). METHODS: A 26-week open-label pilot study in which 16 cases of dcSSc received five infusions of infliximab (5 mg/kg). Clinical assessment included skin sclerosis score, scleroderma health assessment questionnaire, self-reported functional score and physician global visual analogue scale. Collagen turnover, skin biopsy analysis and full safety evaluation were performed. RESULTS: There was no significant change in skin score at 26 weeks but a trend for lower modified Rodnan skin score at 22 weeks (OR 17, 95% CI 6 to 46) compared with peak value (OR 29, 95% CI 11 to 44; p = 0.10). Serum aminoterminal propeptide of type III collagen level was significantly lower at week 26 compared with baseline (p = 0.03). Secretion of type I collagen by dermal fibroblasts was reduced at 26 weeks compared with baseline (p = 0.02). There were no deaths during the study and no suspected unexpected serious adverse reactions. 21 serious adverse events (AE) occurred in seven subjects, mostly attributable to dcSSc. 127 distinct AE occurred in 16 subjects. Of these, 19 AE (15%) were probably or definitely related to infliximab treatment. Eight (50%) patients prematurely discontinued infliximab. Anti-infliximab antibodies developed during the study in five subjects and were significantly associated with suspected infusion reactions (p = 0.025). CONCLUSION: In dcSSc infliximab did not show clear benefit at 26 weeks but was associated with clinical stabilisation and a fall in two laboratory markers of collagen synthesis. The frequency of suspected infusion reactions may warrant additional immunosuppression in any future studies in systemic sclerosis.

Inhibition of a plasminogen activator from oncogenic virus-transformed mouse cells by rabbit antibodies against the enzyme.

Antisera were raised in rabbits against an electrophoretically pure 48 000 dalton plasminogen activator from mouse cells transformed by an oncogenic virus. The IgG fraction of the antisera inhibited 48 000 dalton mouse plasminogen activators from a variety of sources (neoplastic and nonneoplastic), a 29 00) dalton plasminogen activator from mouse urine and a 48 000 dalton plasminogen activator from rat urine. No inhibition was observed of a 75 000 dalton plasminogen activator extracted from mouse lung, of mouse plasmin or of plasminogen activators from human urine and from oncogenic-virus transformed chicken cells. The IgG antibodies were stronger and more specific inhibitors of the 48 000 dalton mouse plasminogen activator than any previously tested compounds.

Sensorineural hearing impairment in patients with Pmp22 duplication, deletion, and frameshift mutations.

OBJECTIVE: To characterize and distinguish the types of sensorineural hearing impairment (SNHI) that occur in hereditary motor and sensory neuropathy Type 1a (HMSN-1a) and hereditary neuropathy with liability to pressure palsies (HNPP), which are caused by deletion or frameshift mutation. STUDY DESIGN: Prospective study. SETTING: Ambulatory patients in a university hospital. PATIENTS: Twelve patients with HMSN-1a due to a duplication of the PMP22 gene on chromosome 17p11.2, 16 patients with HNPP due to the common PMP22 deletion (HNPP del), and 11 HNPP patients with a frame shift mutation (heterozygous PMP22 G-insertion) (HNPP mut), all confirmed by molecular genetic analysis. INTERVENTIONS: Pure-tone audiograms and speech audiograms were obtained. MAIN OUTCOME MEASURES: Results of cross-sectional analysis comprising linear regression of hearing threshold on age. RESULTS: Pure-tone audiograms showed mild to moderate SNHI, predominant at the low and the high frequencies. SNHI showed significant progression by approximately 0.4 dB per year at 0.25 to 4 kHz and up to 1 to 2 dB per year at 4 to 8 kHz. Patients with HMSN-1a had substantial, presumably congenital, SNHI but did not show significant progression beyond presbyacusis. Patients with HNPP showed postnatal onset at age 11 years with progression of SNHI in excess of presbyacusis by 0.4 dB per year. All three types of neuropathy showed normal speech recognition. CONCLUSIONS: All three types of neuropathy showed SNHI with normal speech recognition. HMSN-1a showed stable SNHI without progression beyond presbyacusis. HNPP showed progression beyond presbyacusis with postnatal onset. The differences in SNHI may be explained by the differences in PMP22 expression. The progressive SNHI in HNPP might be explained by the liability for exogenous factors associated with this disorder.

Evaluation of cutaneous blood flow responses by 133Xenon washout and a laser-Doppler flowmeter.

A new method for noninvasive measurement of cutaneous blood flow is laser-Doppler flowmetry. The technique is based on the fact that laser light is back-scattered from the moving red blood cells, with Doppler-shifted frequencies; these impulses lead to photodetectors and are converted to flow signals. In this work we used a new system with a low noise level. Comparison was made between this technique and the atraumatic epicutaneous 133Xenon technique for measurement of cutaneous blood flow during reactive hyperemia and orthostatic pressure changes. The laser-Doppler flowmeter seems to measure blood flow in capillaries as well as in arteriovenous anastomoses, while the 133Xe method probably measures only capillary flow. A calibration of the laser-Doppler method against the 133Xe method would appear to be impossible in skin areas where arteriovenous anastomoses are present. The changes in blood flow during reactive hyperemia, orthostatic pressure changes, and venous stasis were found to be parallel as measured by the two methods in skin areas without shunt vessels. The laser-Doppler flowmeter would appear to be a useful supplement to the 133Xe washout method in cutaneous vascular physiology, but it is important to keep in mind that different parameters may be measured.

The local regulation of blood flow evaluated simultaneously by 133-xenon washout and laser Doppler flowmetry.

The laser Doppler flowmeter and the 133-Xenon washout techniques of measuring cutaneous blood flow were compared for measuring the vasoconstrictor response of the hand during orthostatic maneuvres. Important discrepancies were detected for the two methods. When the hand was lowered by 40 cm a 40% decrease in blood flow was detected by the 133-Xenon method, while a 60% decrease was seen by the laser Doppler technique. Lowering the hand by 50 cm resulted in no further blood flow decrease when using the 133-Xenon method, but an 80% blood flow decrease was recorded with the laser Doppler method. A marked decrease in blood flow was recorded by the laser Doppler technique in hands that were sympathectomized or a hand that was subjected to a nerve blockade, strategies which should eliminate the orthostatic vasoconstrictor response of superficial cutaneous vessels. The 133-Xenon technique did not detect any blood flow changes in hands without sympathetic tone. We found the laser Doppler flowmetry technique unsatisfactory for measurement of blood flow changes that occur in nutritional vessels as this method measures total skin blood flow including non-capillary vessels.

Diet and risk of dementia: Does fat matter?: The Rotterdam Study.

OBJECTIVE: To examine whether high intake of total fat, saturated fatty acids (saturated fat), trans fatty acids (trans fat), and cholesterol and low intake of monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), n-6 PUFA, and n-3 PUFA are associated with increased risk of dementia and its subtypes. METHOD: Data from the Rotterdam Study, a prospective cohort study among elderly, were used. At baseline (1990 to 1993), 5,395 subjects had normal cognition, were noninstitutionalized, and underwent complete dietary assessment by a semiquantitative food-frequency questionnaire. The cohort was continuously monitored for incident dementia, and re-examinations were performed in 1993 to 1994 and 1997 to 1999. The association between fat intake and incident dementia was examined by Cox's proportional hazards models. RESULTS: After a mean follow-up of 6.0 years, 197 subjects developed dementia (146 AD, 29 vascular dementia). High intake of total, saturated, trans fat, and cholesterol and low intake of MUFA, PUFA, n-6 PUFA, and n-3 PUFA were not associated with increased risk of dementia or its subtypes. Rate ratios of dementia per standard deviation increase in intake were for total fat 0.93 (95% CI 0.81 to 1.07), for saturated fat 0.91 (95% CI 0.79 to 1.05), for trans fat 0.90 (95% CI 0.77 to 1.06), for cholesterol 0.93 (95% CI 0.80 to 1.08), for MUFA 0.96 (95% CI 0.84 to 1.10), for PUFA 1.05 (95% CI 0.80 to 1.38), for n-6 PUFA 1.03 (95% CI 0.77 to 1.36), and for n-3 PUFA 1.07 (95% CI 0.94 to 1.22). CONCLUSION: High intake of total, saturated, and trans fat and cholesterol and low intake of MUFA, PUFA, n-6 PUFA, and n-3 PUFA were not associated with increased risk of dementia or its subtypes.

Weight reduction in obese patients with rheumatoid arthritis, with preservation of body cell mass and improvement of physical fitness.

OBJECTIVE: To reduce body weight in obese patients with rheumatoid arthritis (RA) without loss of body cell mass (BCM) and without impairment of physical performance. METHODS: Nineteen overweight RA patients were studied before, during, and after a 12-week weight reducing regime consisting of reduced dietary energy intake, supplemented with a high-protein-low-energy powder preparation, and moderate physical training. Body composition was measured by a four compartment method, which by combining determinations of total body water and total body potassium allows a distinction between the two variable components of fat free mass (FFM): BCM and extracellular water (ECW). Physical fitness was measured by a bicycle exercise test. RESULTS: Mean weight loss during the study was 4.5 kg. The patients lost 9% of their initial fat mass, 3% of initial BCM and 5% of initial ECW. Physical fitness was slightly, but significantly, improved. CONCLUSION: The regime described was successful in achieving a significant weight loss with minimal loss of BCM and maintenance of physical fitness.

The effect of local temperature versus sympathetic tone on digital perfusion in Raynaud's phenomenon.

Matched groups of 7 to 8 patients with primary Raynaud's phenomenon, systemic sclerosis, and undifferentiated connective tissue disease and cold-tolerant normal control subjects were studied by simultaneous digital strain gauge plethysmography and laser Doppler capillary velocimetry during two controlled cycles of hand warming and cooling with and without addition of central cooling and during clinical maneuvers to evoke sympathetic tone. Transient vasoconstrictor responses of comparable degree could be evoked in all patient groups and in both the arterial and microvascular beds. While the addition of central cooling had little influence on arterial flow, patients with systemic sclerosis manifested a failure to maintain nutritive perfusion at finger temperatures associated with Raynaud's phenomenon. Linear regression and multivariate analysis suggested that finger temperature was the principal determinant of arterial flow in systemic sclerosis and that arterial flow was the principal determinant of microvascular perfusion. The inability of patients with systemic sclerosis to maintain nutritive flow in the face of either reflex or cold-induced proximal arterial constriction is consistent with their clinical propensity to ischemic tissue injury and separates these patients physiologically from other forms of Raynaud's phenomenon.

Cyanosis and Raynaud's phenomenon: the relation to underlying disease and venous abnormalities.

Matched groups of 7 to 8 patients with primary Raynaud's phenomenon, systemic sclerosis, and undifferentiated connective tissue disease and cold tolerant normal control subjects were studied by simultaneous digital strain gauge plethysmography and laser Doppler capillary velocimetry during two controlled cycles of hand warming and cooling. Nailfold capillaroscopic assessments and measures of in vivo platelet activation were performed. Triphasic color changes were present in all patients with systemic sclerosis, in 6 of 8 with undifferentiated connective tissue disease, but in only 1 of 7 with primary Raynaud's phenomenon. The occurrence of cyanosis correlated with evidence of impaired venous volume by strain gauge plethysmography and with higher degrees of capillary loop architectural abnormalities. The authors conclude that the presence of digital cyanosis is indicative of connective tissue disease and related to evidence of impaired digital venous capacitance. This may underlie the frequent presence of edema in these patients and may be implicated in the pathogenesis of capillary loop abnormalities.

Effects of disintegration on anaerobic degradation of sewage excess sludge in downflow stationary fixed film digesters.

The effects of mechanical disintegration on anaerobic digestibility of sewage excess sludge in downflow stationary fixed film (DSFF) digesters were investigated on laboratory scale. Mechanical pretreatment using a high pressure homogenizer led to significantly enhanced concentrations of soluble proteins and carbohydrates in the feed sludge. Using DSFF digesters with two different tubular plastic media as support material it was shown that a stable digestion process could be achieved at hydraulic retention times (HRT) down to 5 days. Compared to conventional digesters at 10 d and 15 d HRT respectively, the degradation of volatile solids was enhanced up to 25%, also resulting in a higher specific biogas production. Further investigations on degradation of soluble proteins and carbohydrates showed that a slowly degradable fraction of carbohydrates was released via disintegration. Using the distribution of chain length and the concentrations of volatile fatty acids as process parameters, the dependability on the HRT and the degree of disintegration (the release of soluble COD) predominated the effects of specific surface area of the support media.

[Polyarteritis nodosa diagnosed in acute cholecystectomy]. / Polyarteritis nodosa diagnosticeret ved akut kolecystektomi.

Polyarteritis nodosa (PAN) is a serious systemic vasculitis, which untreated has a five year survival rate of less than 15%. In the present case PAN was diagnosticed in a 72-year old Asian woman by microscopy of a gall bladder in acalculous cholecystitis. We conclude that PAN must be considered in patients with symptoms from several different organs and evidence of vascular involvement can be obtained by histological investigation of material from involved organs or mesenterial angiography.

Ketanserin in the treatment of Raynaud's phenomenon associated with generalized scleroderma.

The efficacy of the 5-HT-2-receptor antagonist, ketanserin, in the treatment of Raynaud's phenomenon was assessed in a double-blind, placebo-controlled, crossover trial in nine patients with generalized scleroderma (GS). Each patient received ketanserin 20 mg or placebo three times a day in the 1st week and 40 mg ketanserin or placebo three times a day for the remaining 4 weeks, and was then crossed over for 5 weeks. Measurements were made of finger blood pressure and flow during a cold challenge test and patients recorded numbers of Raynaud's attacks. No significant improvement was found in reactions to cold provocation or in numbers of Raynaud's attacks during ketanserin treatment, but intolerable side-effects were common. Interactions with concomitant medication might be a possible explanation for this. We conclude that ketanserin in the dose given, is not effective in the treatment of Raynaud's phenomenon in GS.