Long-term evaluation of activated carbon as an adsorbent for biogas desulfurization.

In this study, granular activated carbon (GAC) was used as an adsorbent for biogas desulfurization. Biogas containing 932-2,350 ppm of H2S was collected from an anaerobic digester to treat the wastewater from a dairy farm with about 200 cows. An adsorption test was performed by introducing the biogas to a column that was packed with approximately 50 L of commercial GAC. The operation ceased if the effluent gas had an H2S concentration of over 100 ppm. The GAC was replaced by a given weight of new GAC in a subsequent test. According to the results, for H2S concentrations in the range of 932-1,560 ppm (average±SD = 1,260 ± 256 ppm), 1 kg of the GAC yielded biogas treatment capacities of 568 ± 112 m3 and H2S adsorption capacities of 979 ± 235 g. For the higher influent H2S concentrations of 2,110 ± 219 ppm, the biogas treatment and H2S-adsorption capacities decreased to 229 ± 18 m3 and 668 ± 47 g, respectively. An estimation indicated a requisite cost of US$16.5 for the purification of 1,000 m3 of biogas containing 2,110 ppm of H2S. This cost is approximately 5% of US$330, the value of 1,000 m3 of biogas. IMPLICATIONS: Biogas generated from anaerobic digesters of animal manure and municipal wastewater sludge contains hydrogen sulfide which must be removed before it can be combusted in electricity-generation engines. This study demonstrated that commercial activated carbon adsorption can be an economical and effective approach for removing hydrogen sulfide from biogas. In this study, granular activated carbon (GAC) was used as an adsorbent for biogas desulfurization. The biogas containing 932-2,350 ppm of H2S was collected from an anaerobic digester for treating wastewater collected from a 200 dairy farm. The adsorption test was performed by introducing the biogas to a PVC column packed with a commercial GAC of around 50 L. Operation ceased if the effluent gas had an H2S concentration of over 100 ppm. A given weight of the new GAC was replaced for a successive test.

Endoscopic management of pediatric sinonasal schwannoma: case report.

OBJECTIVES: To describe an extremely rare pediatric sinonasal schwannoma, and to reviewmanagement strategies and relevant literature. METHODS: Case report of pediatric sinonasal schwannoma, that was imaged with computed tomography and magnetic resonance imaging and managed endoscopically. Immunohistochemical analysis was performed to determine pathology. RESULTS: A 12-year-old girl presented with a 2-month history of progressive left exophthalmos. Imaging studies showed a large heterogeneous tumour arising from the ethmoid sinus and extending to the base of the skull and to the orbital cavity. The lesion was removed with an endonasal radical excision. The final pathological diagnosis was schwannoma. There was no tumour recurrence or any major complication during the 2-year follow up. CONCLUSION: Schwannoma should be considered in the differential diagnosis for pediatric patients with intranasal masses. Depending on the location and extent of the tumour, endonasal endoscopic excision could be a suitable management strategy.

Regulating colored textile wastewater by 3/31 wavelength ADMI methods in Taiwan.

The wastewater from textile dyeing facilities is difficult to treat satisfactorily because of high compositional variability and high color intensity. To reduce colored effluents discharged into watercourses, the government of Taiwan adopted the Effluent True Color Standard in 1998. The true color discharge limit is 400 American Dye Manufactures Institute (ADMI) units. The adopted analytical method is the ADMI Tristimulus Filter Method (3 wavelength (WL) method), and the 31 WL ADMI method might be also adopted as an alternative for color value measurement. The refractory nature of textile dyes and the introduction of this new regulation present an environmental challenge to the Taiwanese textile industry. The main objectives of this study were to (1) evaluate the efficacy of current wastewater treatment systems for controlling the colored textile wastewater discharges, and (2) evaluate the correlations between 3 and 31 WL ADMI methods. Ten representative textile wastewater treatment facilities employing biological and chemical coagulation treatment technologies were selected to perform a 10-consecutive-day effluent sampling and analysis. Results show that a significant difference between 3 and 31 ADMI methods was observed. These two ADMI methods cannot be substituted for each other, and the discharge standard should be determined based on the selected testing method. Investigation results also suggest that the commonly used wastewater treatment technology (biological + chemical coagulation) fails to effectively remove dye from the colored textile wastewater. Sodium hypochlorite (NaOCl) addition was applied by most facilities as the temporary post-polishment step to comply with the color discharge standard.

Biotrickling filtration of nitric oxide.

A biotrickling filter with blast-furnace slag packings (sizes = 20-40 mm and specific surface area = 120 m2/m3) was utilized to treat NO in an air stream. The operational stability, as well as the effects of gas empty-bed retention time (EBRT) and nutrient addition on the removal ability of NO, were tested. Approximately six weeks were required for the development of a biofilm for NO degradation, and a two-week organic carbon deficiency resulted in the detachment of biofilms from the packing surfaces. A steady removal rate of 80% was attained at specified influent NO concentrations of 892 to 1237 ppm and an EBRT of 118 sec. The effluent NO concentration diminished exponentially with enlarging EBRT, with influent NO concentrations of 203-898 ppm, and EBRTs of 25 to 118 sec. Nutrient addition is essential for efficient removal of the influent NO. Mass ratios of C: P: N = 7: 1: 30 and NaHCO3: NO-N = 6.3 could be used for practical applications.

Kinetics of catalytic oxidation of benzene, n-hexane, and emission gas from a refinery oil/water separator over a chromium oxide catalyst.

With the advances made in the past decade, catalytic incineration of volatile organic compounds (VOCs) has become the technology of choice in a wide range of pollution abatement strategies. In this study, a test was undertaken for the catalytic incineration, over a chromium oxide (Cr2O3) catalyst, of n-hexane, benzene, and an emission air/vapor mixture collected from an oil/water separator of a refinery. Reactions were carried out by controlling the feed stream to constant VOC concentrations and temperatures, in the ranges of 1300-14,700 mg/m3 and 240-400 degrees C, respectively. The destruction efficiency for each of the three VOCs as a function of influent gas temperature and empty bed gas residence time was obtained. Results indicate that n-hexane and the oil vapor with a composition of straight- and branch-chain aliphatic hydrocarbons exhibited similar catalytic incineration effects, while benzene required a higher incineration temperature or longer gas retention time to achieve comparable results. In the range of the VOC concentrations studied, at a given gas residence time, increasing the operating temperature of the catalyst bed increased the destruction efficiency. However, the much higher temperatures required for a destruction efficiency of over 99% may be not cost-effective and are not suggested. A first-order kinetics with respect to VOC concentration and an Arrhenius temperature dependence of the kinetic constant appeared to be an adequate representation for the catalytic oxidation of these volatile organics. Activation energy and kinetic constants were estimated for each of the VOCs. Low-temperature destruction of the target volatile organics could be achieved by using the Cr2O3 catalyst.

Performance characteristics of a regenerative catalytic oxidizer for treating VOC-contaminated airstreams.

A pilot apparatus of a regenerative catalytic oxidizer (RCO) equipped with two electrical heaters and two 20-cm i.d. x 200-cm height regenerative beds was used to treat methyl ethyl ketone (MEK) and toluene, respectively, in an airstream. The regenerative beds were packed with gravel (approximate particle size 1.25 cm, specific area 205 m2/m3, and specific heat capacity 840 J/kg degree C) as a solid regenerative material and K-type thermal couples for measuring solid and gas temperatures, respectively. The catalyst bed temperature was kept around 400 degrees C and the gas superficial velocity was operated at 0.234 m/sec. This investigation measured and analyzed distributions of solid and gas temperatures with operating time and variations of volatile organic compound (VOC) concentrations in the regenerative beds. The overall VOC removal efficiency exceeded 98% for MEK and 95% for toluene. Degradation of VOCs will exist for MEK on the surface of solid material (gravel) in the temperature range of 330-400 degrees C, but toluene does not exhibit this phenomenon.

Intracranial fatigable ptosis.

Two patients sought treatment for bilateral fatigable ptosis; one patient had a hematoma, and the other patient had an intracranial metastasis. Compression of the central caudal nucleus in the dorsal midbrain is proposed as the cause of this ptosis, and an alteration of central acetylcholine neurotransmission may contribute to ocular fatigability. Because symptoms that suggest fatigable ptosis can be similar to those that suggest ocular myasthenia gravis, a careful evaluation is necessary to avoid misinterpretation.

Rhinosino-orbital mucormycosis causing cavernous sinus thrombosis and internal carotid artery occlusion: radiological findings in a patient with treatment failure.

The authors describe a case of rhinosino-orbital mucormycosis with cavernous sinus thrombosis in association with internal carotid artery occlusion diagnosed by use of computerized tomography (CT) and magnetic resonance imaging (MRI). Cranial CT is a useful imaging tool in the diagnosis of rhinosinal invasive fungal disease and MRI offers excellent aid in the detection of intracranial extension. Early diagnosis and rapid institution of surgical debridement and antifungal therapy is the rule of thumb in treating this disorder. In our patient, surgically inaccessible bone lesion and involvement of the central nervous system are taken as major causes for his grave outcome. In addition, failure to advance appropriate amphotericin B dosage may also make the infectious process uncontrollable in this patient.

Treatment of ethylether in air stream by a biotrickling filter packed with slags.

This paper reports results of studies using a biotrickling filter with blast-furnace slag packings (sizes = 2-4 cm and specific surface area = 120 m2/m3) for treatment of ethylether in air stream. Effects of volumetric loading, superficial gas velocity, empty bed gas retention time, recirculation liquid flow rate, and biofilm renewal on the ethylether removal efficiency and elimination capacity were tested. Results indicate that ethylether removal efficieincies of more than 95% were obtained with an empty bed retention time (EBRT) of 113 sec and loadings of lower than 70 g/m3/hr. At an EBRT of 57 sec, removal efficiencies of more than 90% could only be obtained with loadings of lower than 35 g/m3/hr. The maximum elimination capacities were 71 and 45 g/m3/hr for EBRT = 113 and 57 sec, respectively. The maximum ethylether elimination capacities were 71 and 96 g/m3/hr, respectively, before and after the renewal at EBRT = 113 sec. With an EBRT of 113 sec and a loading of lower than 38 g/m3/hr, the removal efficiency was nearly independent of the superficial liquid recirculation velocity in the range of 3.6 to 9.6 m3/m2/hr. From data regression, simplified masstransfer limited, and reaction- and mass-transfer limited models correlating the contaminant concentration and the packing height were proposed and verified. The former model is applicable for cases of low influent contaminant concentrations or loadings, and the latter is applicable for cases of higher ones. Finally, CO2 conversion efficiencies of approximately 90% for the influent ethylether were obtained. The value is comparable to data reported from other related studies.

Magnetic resonance images of neuronal migration anomalies.

Neuronal migration anomalies are a spectrum of brain malformations caused by insults to migrating neuroblasts during the sixth week to fifth month of gestation. To study the characteristics of MRI findings in migration anomalies, MR images of 36 patients (28 children and 8 adults) with migration anomalies were evaluated. Five patients had lissencephaly, eight had pachygyria, twelve had schizencephaly, six had heterotopias of gray matter, three had hemimegalencephaly, and two had polymicrogyria. The frequency of migration anomalies was 0.51% of all cranial MRI studies and 1.21% of pediatric cranial MRI studies at our hospital. The major clinical presentations of these patients were seizure (64%), development delay (42%), motor deficits (42%) and mental retardation (25%). Twenty-five patients (69%) associated with other brain anomalies, including: other migration anomalies in 12 cases (33%), absence of the septum pellucidum in 10 cases (28%), Dandy-Walker malformation/variant in 5 cases, arachnoid cyst in 4 cases, agenesis of the corpus callosum in 3 cases, holoprosencephaly in 2 cases, mega cisterna magna in 1 case and cephalocele in 1 case. Some of them presented with multiple complicated anomalies. As MR imaging provides superb gray-white matter distinction, details of cortical anatomy and multiplanar capability, it can clearly delineate the detail morphologic changes of the brain caused by neuronal migration disorders as well as the associated anomalies.

Etiology, timing of insult, and neuropathology of cerebral palsy evaluated with magnetic resonance imaging.

To define the patterns of pathologic changes in cerebral palsy (CP) and to assess the etiology and time of brain damage, we reviewed the magnetic resonance images and clinical records of 86 pediatric CP patients seen over 8 years. Patients were divided into two groups, based on the gestational age at birth. The majority of CP patients (69) had spasticity. In the premature group (< 37 wk gestational age) n = 27), spastic diplegia (12 patients) and quadriplegia (8) were the major subtypes. In the term group (> or = 37 wk gestational age) ( n = 59), spastic hemiplegia (23) and quadriplegia (12) were most common. The other main clinical manifestations in the two groups were seizures (36) and mental retardation (15). Magnetic resonance (MR) imaging provided significant findings in 82 patients (95%). In the 27 patients born prematurely, MR imaging revealed periventricular leukomalacia (17), multicystic encephalomalacia (3), cortical and subcortical atrophy (4), migration disorders (2), and basal ganglia injury (1). Among the patients born at term, the MR imaging findings were more heterogeneous; they included cortical and subcortical atrophy (17), brain malformations (17), periventricular leukomalacia (6), multicystic encephalomalacia (5), porencephaly (4), hemiatrophy (3), delayed myelination (3), and none (4). MR imaging alone could define the time of brain insults in 73 of our 86 CP patients. Combined with clinical histories, MR imaging could help assess the time of insult in 93% of patients. The brain insults occurred prenatally in 34 of our patients, perinatally in 37, and postnatally in eight. The time of insult could not be determined in six patients. In the premature patients, the insult occurred most frequently perinatally (74%), whereas in the term group it occurred most frequently prenatally (54%). MR imaging was found to be very helpful in the evaluation of the various neuropathologic changes in CP, in the depiction of the etiology, and in the determination of the time of brain injury.

Screening of biofiltering material for VOC treatment.

Screening of biofiltering material for treatment of volatile organic compounds was performed by using a gas stream containing methyl ethyl ketone (MEK) as a target pollutant. Filtering media (FM) for screening were prepared by blending compost (such as pig and cow manure) and filling material (such as fern chips, wheat bran, and bagasse). Results show that a blend of pig manure/fern chips = 9:1 (wt basis) was superior with respect to the stability of the pH and the water-holding capacity of the FM and in the capacity for treating the target compound. Complete removal of the target compound was obtained at an organic loading of 100 g per cubic meter of filtering media per hour. By using the screened FM for treating MEK and toluene, long-term stability (> 1,200 hours) and complete removal can be obtained at an organic loading of 50 g per cubic meter of FM per hour for either compound.

Prediction of total cholesterol: high-density-lipoprotein-cholesterol ratio in young adults.

Abnormal cholesterol fraction is an essential risk factor for atherosclerosis of large cerebral arteries in young Asians. In order to reduce the medical cost and social resource for cholesterol electrophoresis, especially in undeveloped and developing Asian countries, we evaluated the validity of Nanji's GUT score for predicting TC: HDLC ratio in this population. Results showed that GUT score only predicted 71% of them. We also tested the predictive power of CUT index, and predicting rate was 81%. Therefore, Nanji's GUT score is not an ideal surrogate for cholesterol electrophoresis. We recommend CUT index to screen for high-risk subjects till a new method can satisfy the economic pattern in Asian countries.

Bilateral cheiro-oral syndrome.

Eight cases of pure bilateral cheiro-oral syndrome (COS) are reported. The location and etiology of lesion were well defined in six cases, including pontine infarct in three, and brainstem hemorrhage, unilateral thalamic infarct and bilateral subdural hematoma in one patient each respectively. Neuroimaging and neurophysiological studies were normal in another two patients. Taken together with the previous five reported cases of bilateral COS, pons is the most frequent site for presentation even in the absence of associated brainstem signs.

The lipoprotein profile of young adults with cerebral atherosclerosis.

In order to elucidate the relationship between the lipoprotein profile and large cerebral artery atherosclerosis in the young adults living in developing Asian countries, the serum lipoprotein profile and the luminal diameter of large cerebral arteries (internal carotid, middle/anterior cerebral and vertebrobasilar arteries) were measured and correlated in 67 young Taiwanese with non-embolic cerebral infarct (CI). Totally 23 (21.9%) patients had atherosclerotic stenosis. A significant elevation of the serum total cholesterol (TC), triglyceride, total lipids, beta-lipoprotein (beta-LP) and pre-beta-LP level was found in atherosclerotic CI patients. But multiple regression analysis showed only the serum beta-LP (p = 0.0041) and TC (p = 0.0324) level to be the independent risk factors for atherosclerosis. Secondary dyslipoproteinemia is the main cause for hyperlipoproteinemia in our atherosclerotic patients. Therefore, an abnormal lipoprotein profile is linked to large cerebral artery atherosclerosis in young Asians regardless of ethnic group. A tailored program is recommended to modify the life style and dietary habit, as well as to gain access to secondary control for large cerebral atherosclerosis prevention in developing countries.

Mandibular arteriovenous malformation diagnosed by MR and MRA: a case report.

A case of mandibular arteriovenous malformation (AVM) is presented. Prompt diagnosis and appropriate management are essential due to massive bleeding or even death after dental extraction or biopsy. Angiography remains the gold standard in detecting the lesion. Magnetic resonance (MR) imaging with spin-echo sequences reveals the vascular malformation as signal-void. MR angiography can demonstrate the nidus, dilated artery and vein. MR imaging and MR angiography can supplement angiography in the diagnosis of mandibular AVM.

Computed tomography and magnetic resonance imaging of intracranial ependymomas.

We evaluated the neuroimages of 18 pathologically proven cases of ependymoma, 15 cases by CT evaluation and 9 cases by MRI evaluations. In 7 cases of supratentorial ependymomas, 4 were intraparenchymal and 3 were intraventricular ependymomas originating from the ependymal lining layer, the floor of the lateral ventricle, which was best demonstrated on a sagittal MR image. For the cases of infratentorial ependymomas, all were intraventricular. Evidence of seeding through the cerebrospinal fluid pathway to the basal cisterns, spinal cord or ventricles was presented in 6 cases which were particularly well demonstrated in the sagittal section with gadolinium-DTPA enhanced MR imaging. On CT scan, isodense tumors with various portions of high enhancement within a moderate enhancement mass were the most frequent features. In MRI, isointensity relative to gray matter on T1-weighted images and hyperintensity on mild and heavy T2-weighted images were most frequently seen. The signal heterogeneity representing soft tissue, small cysts, necrosis, calcification, vessels or hemosiderin was better visualized in MRI which offered a better assessment of the character of tumor compositions. The soft tissue mass, calcification and cysts as revealed in both CT and MRI are nonspecific, but the location, ages, CSF seeding and particularly, superior MR images can offer very important clues for the diagnosis of ependymoma.

[Metastasis involving the leptomeninges and ventricles of the brain--CT evaluation].

The diagnosis of leptomeningeal or ventricular metastasis by cranial computerized tomography (CT) contributes to earlier treatment and sometimes alters the management of patients with intra- or extra-cranial malignancy. In 20 cases whose metastasis were spreaded via CSF seeding, the abnormal CT findings were 1) mass or nodule in the ventricles or subarachnoid space, 2) ependymal, subependymal enhancement, 3) sulcal, gyral or cisternal enhancement, 4) hydrocephalus not related to the obstruction of primary tumor, 5) falx or tentorial enhancement. In another 8 cases, the metastasis developed through hematogeneous spreading to the choroid plexus or paraventricular parenchyma. The mass or nodule within the ventricles could be well identified with enhanced CT scan. The involved ventricles, in order of frequency, were lateral, 3rd, and 4th ventricles in our series.

MRI manifestations of leptomeningeal metastasis.

Twenty-six cases with leptomeningeal metastasis were analyzed and Gd-DTPA enhanced MR imaging was found to be the most useful tool for making the diagnosis. The important manifestations in order of frequency were: 1) leptomeningeal enhancement; 2) ependymal enhancement; 3) plaque, nodule or mass in the subarachnoid space or ventricles; 4) nerve root thickening; and 5) ventricular dilatation not related to the obstruction of the primary neoplasm. A review of the literature has shown that intracranial leptomeningeal metastasis from spinal cord astrocytoma are very rare. In our series, 3 cases with primary brain tumors developed spinal subarachnoid involvement. This paper also reviews 1 case with thoracic cord astrocytoma which developed multiple intracranial leptomeningeal metastasis.