Mass transfer enhancement and improved nitrification in MABR through specific membrane configuration.

One of the main energy consumptions in wastewater treatment plants (WWTPs) is due to the oxygenation of aerobic biological processes. In order to approach to an energy self-sufficient scenario in WWTPs, Membrane Aerated Biofilm Reactors (MABRs) provide a good opportunity to reduce the impact of aeration on the global energy balance. However, mass transfer limitations derived from poor flow distribution must be tackled to take advantage of this technology. In this work, in order to improve mass transfer between biofilm and bulk water, a specific configuration was developed and studied at laboratory scale, aimed at compactness, energy efficiency and high nitrification rates. Nitrification rates were higher in the innovative configuration than in the conventional one, achieving a Volumetric Nitrification Rate (VNR) as high as 575.84 g NH4-N m-3 d-1, which is comparable with confirmed technologies. Regarding energy consumption due to aeration, a reduction of 83.7% was reached in comparison with aeration through diffusers with the same Oxygen Transfer Efficiency (OTE). These results highlight the importance of hydrodynamic conditions and the membranes configuration on treatment performance.

Periodic venting of MABR lumen allows high removal rates and high gas-transfer efficiencies.

The membrane-aerated biofilm reactor (MABR) is a novel treatment technology that employs gas-supplying membranes to deliver oxygen directly to a biofilm growing on the membrane surface. When operated with closed-end membranes, the MABR provides 100-percent oxygen transfer efficiencies (OTE), resulting in significant energy savings. However, closed-end MABRs are more sensitive to back-diffusion of inert gases, such as nitrogen. Back-diffusion reduces the average oxygen transfer rates (OTR), consequently decreasing the average contaminant removal fluxes (J). We hypothesized that venting the membrane lumen periodically would increase the OTR and J. Using an experimental flow cell and mathematical modeling, we showed that back-diffusion gas profiles developed over relatively long timescales. Thus, very short ventings could re-establish uniform gas profiles for relatively long time periods. Using modeling, we systematically explored the effect of the venting interval (time between ventings). At moderate venting intervals, opening the membrane for 20 s every 30 min, the venting significantly increased the average OTR and J without substantially impacting the OTEs. When the interval was short enough, in this case shorter than 20 min, the OTR was actually higher than for continuous open-end operation. Our results show that periodic venting is a promising strategy to combine the advantages of open-end and closed end operation, maximizing both the OTR and OTE.

Comparison between a fixed bed hybrid membrane bioreactor and a conventional membrane bioreactor for municipal wastewater treatment: a pilot-scale study.

A hybrid membrane bioreactor (HMBR) was developed, by adding biofilm support media into a conventional membrane bioreactor (CMBR), and operated in parallel with a CMBR. Results showed that effluent quality was significantly better with the HMBR. The removal efficiencies of COD, BOD5, NH4(+)-N and TN with the HMBR were 84%, 98%, 97% and 75%, respectively, as compared to 80%, 96%, 93% and 38% with the CMBR. There were no differences in phosphorus removal. The membrane fouling rate in the HMBR was on average only 57% of that in the CMBR. The lower concentration of colloidal biopolymer clusters in the HMBR sludge, probably due to their retention by the biofilm, could be partially responsible for this difference. Filterability and settleability of the sludge were also better in the HMBR. Consequently, it is concluded that the addition of fixed support media for biofilm growth can improve the performance of CMBRs.

Evaluation of a hybrid vertical membrane bioreactor (HVMBR) for wastewater treatment.

A new hybrid membrane bioreactor (HMBR) has been developed to obtain a compact module, with a small footprint and low requirement for aeration. The aim of this research was to assess its performance. The system consists of a single vertical reactor with a filtration membrane unit and, above this, a sponge fixed bed as support medium. The aeration system is located under the membrane unit, allowing for membrane cleaning, oxygenation, biofilm thickness control and bulk liquid mixing. Operated under continuous aeration, a bench-scale reactor (70 L) was fed with pre-treated, raw (unsettled) municipal wastewater. BOD(5) and suspended solids removal efficiencies (96 and 99% respectively) were comparable to those obtained with other membrane bioreactors (MBRs). Total nitrogen removal efficiencies of 80% were achieved, which is better than those obtained in other HMBRs and similar to the values reached using more complex MBRs with extra anoxic tanks, intermittent aeration or internal deflectors.

[Frontal seizures recorded by magnetoencephalography. Case report]. / Crisis frontales registradas mediante magnetoencefalografía. Caso clínico.

INTRODUCTION: This paper reports the usefulness of magnetoencephalography (MEG) in the anatomical localization of the onset and spread of seizures. CASE REPORT: In a 34-year-old male patient who suffered from drug-resistant complex partial seizures (sometimes generalized) with loss of awareness, magnetic resonance imaging revealed a probable left frontobasal cortical dysplasia. Ictal scalp electroencephalogram showed left frontotemporal theta waves. Electrocorticography (ECoG) registered interictal polyspike discharges and located the seizure onset in the lateral orbital side of the left frontal lobe. Three seizures were registered by MEG, clinically similar to the ones usually experienced by the patient. MEG ictal spike dipole location showed seizure onset coming from the left inferior frontal gyrus (as the ECoG), spreading on to other frontal areas, insula and temporal lobe, all in the left hemisphere. CONCLUSION: MEG may be considered as a useful diagnosis modality in the study of partial seizure physiopathology as well as in its presurgical evaluation.

Crisis frontales registradas mediante magnetoencefalografía. Caso clínico / Frontal seizures recorded by magnetoencephalography. Case report

Introducción. Este artículo expone un ejemplo de la utilidadde la magnetoencefalografía (MEG) en la localización anatómicadel inicio y la propagación de las crisis epilépticas. Caso clínico.Se trata de un paciente de 34 años con crisis parciales complejas farmacorresistentes.La resonancia magnética presenta una probabledisplasia cortical frontobasal izquierda. El electroencefalograma ictalde superficie revela ondas theta frontotemporales izquierdas. Enel registro con electrodos subdurales se demuestra la existencia deanomalías epileptiformes interictales durante el sueño, entre las quepredominan las polipuntas, y crisis de inicio focal en la cara lateroorbitariadel lóbulo frontal izquierdo. La MEG registra tres crisis clínicamentesimilares a las experimentadas por el paciente y permitelocalizar el inicio de las crisis en la circunvolución frontal inferiorizquierda, con propagación a otras áreas frontales, la ínsula y ellóbulo temporal, todo ello en el hemisferio izquierdo. Conclusión. LaMEG puede considerarse como un elemento diagnóstico útil en el estudiode la fisiopatología de las crisis parciales, así como en la evaluaciónprequirúrgica

Introduction. This paper reports the usefulness of magnetoencephalography (MEG) in the anatomical localization ofthe onset and spread of seizures. Case report. In a 34-year-old male patient who suffered from drug-resistant complex partialseizures (sometimes generalized) with loss of awareness, magnetic resonance imaging revealed a probable left frontobasalcortical dysplasia. Ictal scalp electroencephalogram showed left frontotemporal theta waves. Electrocorticography (ECoG)registered interictal polyspike discharges and located the seizure onset in the lateral orbital side of the left frontal lobe. Threeseizures were registered by MEG, clinically similar to the ones usually experienced by the patient. MEG ictal spike dipolelocation showed seizure onset coming from the left inferior frontal gyrus (as the ECoG), spreading on to other frontal areas,insula and temporal lobe, all in the left hemisphere. Conclusion. MEG may be considered as a useful diagnosis modality in thestudy of partial seizure physiopathology as well as in its presurgical evaluation

[Blepharospasm and blepharocolysis. Different sides of the same coin]. / Blefaroespasmo y blefarocolisis. Caras diferentes de una misma moneda.

INTRODUCTION: The eyelid movements are mediated mainly by the orbicularis oculi (OO) and the levator palpebrae superioris (LPS) muscles. Dissociated upper lid functions exhibit different counterbalanced action of these muscles, and in blinking they show a strictly reciprocal innervation. The disturbance of this close LPS-OO relationship likely leads to many of the central lid movement disorders. DEVELOPMENT: Two major lid postural disorders, the blepharospasm (BSP) and the blepharocolysis (BCO), share two different clinical aspects: the involuntary eyelids' closure along with the inability to open the eyes. BSP consists of an involuntary overactivity of the OO, with LPS co-contraction activity, and is expressed as frequent and prolonged blinks, clonic bursts, prolonged tonic contraction or a blend of all of them. BCO (commonly named 'so-called lid opening apraxia') is an involuntary overinhibition of the LPS muscles with no evidence of ongoing OO activity; it exists a co-inhibition of these muscles. BSP and BCO occur in many instances of idiopathic dystonias and basal ganglia diseases and, less frequently, in rostral brainstem lesions. Both may coincide in the same patient. CONCLUSIONS: BSP and BCO should be considered different expressions of the dystonic focal eyelid movement disorders, related to the increase of the two counteracting components of the normal eyelid motor and blinking patterns: the excessive OO activation in the BSP; the excessive LPS inhibition in the BCO.

Blefaroespasmo y blefarocolisis. Caras diferentes de una misma moneda / Blepharospasm and blepharocolysis. different sides of the same coin

Introducción. Los movimientos palpebrales están mediados principalmente por los músculos orbicular de los ojos (OO) y elevador de los párpados superiores (LPS). Tanto la actividad de cierre-apertura ocular como el parpadeo muestran una inervación recíproca muy precisa de estos músculos. La alteración de esta estrecha relación funcional entre el LPS y el OO probablemente dé lugar a muchos de los trastornos motores palpebrales centrales. Desarrollo. Existen dos trastornos de la motilidad palpebral que tienen en común dos aspectos clínicos diferenciados: el cierre involuntario de los ojos y la dificultad o imposibilidad de abrirlos. Son el blefaroespasmo (BSP) y la blefarocolisis (BCO). En el BSP los ojos se cierran involuntariamente por la contracción espasmódica de los músculos OO; existe una cocontracción con el LPS que se expresa en forma de parpadeos frecuentes y prolongados, descargas clónicas, contracción tónica prolongada o una mezcla de todos ellos. En la BCO -con frecuencia mal denominada ‘apraxia de la apertura palpebral’- existe un cierre excesivo de los ojos por inhibición involuntaria de los músculos LPS, sin que se asocie contracción de los OO; se produce, podría decirse, una coinhibición entre ellos. El BSP y la BCO pueden coincidir en el mismo paciente, y se da en muchos casos de distonías idiopáticas y en enfermedades de los ganglios basales, y también, aunque menos frecuentemente, en lesiones troncoencefálicas rostrales. Conclusiones. El BSP y la BCO deben considerarse expresiones diferentes de un trastorno distónico focal palpebral que se produce por la alteración de cada uno de los dos componentes contrapuestos que configuran el mecanismo normal del movimiento palpebral y el parpadeo: la activación excesiva del OO, en el caso del BSP; la inhibición excesiva del LPS, en el caso de la BCO

Introduction. The eyelid movements are mediated mainly by the orbicularis oculi (OO) and the levator palpebrae superioris (LPS) muscles. Dissociated upper lid functions exhibit different counterbalanced action of these muscles, and in blinking they show a strictly reciprocal innervation. The disturbance of this close LPS-OO relationship likely leads to many of the central lid movement disorders. Development. Two major lid postural disorders, the blepharospasm (BSP) and the blepharocolysis (BCO), share two different clinical aspects: the involuntary eyelids’ closure along with the inability to open the eyes. BSP consists of an involuntary overactivity of the OO, with LPS co-contraction activity, and is expressed as frequent and prolonged blinks, clonic bursts, prolonged tonic contraction or a blend of all of them. BCO (commonly named ‘so-called lid opening apraxia’) is an involuntary overinhibition of the LPS muscles with no evidence of ongoing OO activity; it exists a co-inhibition of these muscles. BSP and BCO occur in many instances of idiopathic dystonias and basal ganglia diseases and, less frequently, in rostral brainstem lesions. Both may coincide in the same patient. Conclusions. BSP and BCO should be considered different expressions of the dystonic focal eyelid movement disorders, related to the increase of the two counter-acting components of the normal eyelid motor and blinking patterns: the excessive OO activation in the BSP; the excessive LPS inhibition in the BCO

[Modified aspiration needle muscular biopsy in neuromuscular diseases. Use and advantages over open surgical biopsy]. / Estudio de las enfermedades neuromusculares por biopsia percutánea mediante aguja con aspiración modificada. Utilidad y ventajas sobre la biopsia quirúrgica.

OBJECTIVE: To evaluate aspiration needle muscular biopsy as an alternative to surgical open biopsy, so we focus on its results and tolerance. PATIENTS AND METHODS: We studied 150 patients with muscular pathology of every kind, and aged between 10 and 86 years, using a modified Allendale/Liverpool needle which by our indication has a built-in lateral funnel that provides faultless aspiration in 100% of cases. Percutaneous biopsy neuromuscular disorders study with modified aspiration Allendale needle: use and advantages over surgical biopsy. RESULTS: The biopsy, which was very well tolerated by the patients, children in particular, left no scar and produced fine samples for standard, immunohistochemical, ultrastructural, biochemical and genetic investigation. In children beyond 10 years of age no general anesthetics was required and in many 4-10 years neither. A number of unsuspected cases of mitochondrial or inflammatory myopathy were detected. Patients with cramps or unclearly defined clinical picture did, however, show frequent morphological pathology. In just three cases samples were defective; all others produced changes of diagnostic or prognostic value with 8% without morphologically abnormal changes. CONCLUSIONS: Modified aspiration needle biopsy is the choice method to study muscle. The samples are of excellent quality allowing for any kind of morphological, biochemical or genetic investigation. The procedure is routinely very well tolerated by patients so is very superior to open surgical biopsy, that we still use for infants in selected cases.

Estudio de las enfermedades neuromusculares por biopsia percutánea mediante aguja con aspiración modificada. Utilidad y ventajas sobre la biopsia quirúrgica / Modified aspiration needle muscular biopsy in neuromuscular diseases. Use and advantages over open surgical biopsy

Introducción. La biopsia muscular percutánea es una alternativa a la biopsia quirúrgica abierta; intentamos evaluar sus ventajas y resultados. Pacientes y métodos. Se estudiaron 150 pacientes entre 10 y 86 años empleando de una aguja con aspiración de tipo Allendale/Liverpool, con una embocadura lateral para efectuar la aspiración. Los pacientes presentaban cuadros diversos de patología muscular. Resultados. La tolerancia es muy buena, y en niños de edad inferior a 10 años, muy a menudo, no se requiere anestesia general. No queda cicatriz y el material es suficiente para el estudio morfológico, histoquímico, citoarquitectural, bioquímico y genético. De todos los casos, solamente en tres las tomas no fueron valorables; el resto de las tomas aportaron información diagnóstica y pronóstica, o no específica pero pronóstica, y en un 8 por ciento fueron normales. Se han detectado numerosos casos de miopatía inflamatoria o mitocondrial no sospechados clínicamente. Los grupos de pacientes con sintomatología mal definida y calambres muestran una elevada tasa de patología subyacente. Conclusión. Los resultados muestran que la biopsia por aguja con aspiración con la modificación sugerida por nosotros es el procedimiento de elección para el estudio del músculo; produce un material que permite un estudio morfológico completo y fiable, así como estudios bioquímicos y genéticos, con una mínima molestia, y, en conjunto, es claramente ventajosa sobre la biopsia quirúrgica, que nosotros reservamos para casos aislados en niños muy pequeños (AU)

Objective. To evaluate aspiration needle muscular biopsy as an alternative to surgical open biopsy, so we focus on its results and tolerance. Patients and methods. We studied 150 patients with muscular pathology of every kind, and aged between 10 and 86 years, using a modified Allendale/Liverpool needle which by our indication has a built-in lateral funnel that provides faultless aspiration in 100% of cases. Percutaneous biopsy neuromuscular disorders study with modified aspiration Allendale needle: use and advantages over surgical biopsy. Results. The biopsy, which was very well tolerated by the patients, children in particular, left no scar and produced fine samples for standard, immunohistochemical, ultrastructural, biochemical and genetic investigation. In children beyond 10 years of age no general anesthetics was required and in many 4-10 years neither. A number of unsuspected cases of mitochondrial or inflammatory myopathy were detected. Patients with cramps or unclearly defined clinical picture did, however, show frequent morphological pathology. In just three cases samples were defective; all others produced changes of diagnostic or prognostic value with 8% without morphologically abnormal changes. Conclusions. Modified aspiration needle biopsy is the choice method to study muscle. The samples are of excellent quality allowing for any kind of morphological, biochemical or genetic investigation. The procedure is routinely very well tolerated by patients so is very superior to open surgical biopsy, that we still use for infants in selected cases (AU)

[Hereditary sensory and autonomic neuropathies. The neurophysiological and pathological aspects of two cases with congenital insensitivity to pain]. / Neuropatías sensitivas autonómicas hereditarias. Dos casos con insensibilidad congenita al dolor; aspectos neurofisiológicos y patológicos.

AIM: Two patients suffering from congenital insensitivity to pain were studied. They corresponded to types IV and V of the 'hereditary sensory and autonomic neuropathies' (HSAN) classification. CASE REPORTS: The first case showed important autonomic dysfunctions, such as anhidrosis, hyperthermia, skin and bone trophic impairment, and mental retardation; the second one only exhibited alterations in pain and temperature sensibilities. In both, chronic indolent corneal ulcers were also present. Conventional neurophysiological evaluation of the neuromuscular system was normal, but an afferent disturbance of the blink reflex (BR) was evident in both. The sympathetic skin response was absent in the HSAN type IV case and normal in the HSAN type V. Notable reduction of the small myelinated fibres, associated to almost no unmyelinated fibres in the first case, were found in the sural nerve biopsies. CONCLUSIONS: So far there haven't been described BR abnormalities in patients with congenital insensitivity to pain, which should be related to a trigeminal sensory impairment, which could explain the corneal ulcers that suffered these cases. BR studies should be included in the neurophysiological evaluation of the suspected small fibre neuropathies even when there are no facial symptoms shown.

Neuropatías sensitivas autonómicas hereditarias. Dos casos con insensibilidad congénita al dolor: aspectos neurofisiológicos y patológicos / Hereditary sensory and autonomic neuropathies. The neurophysiological and pathological aspects of two cases with congenital insensitivity to pain

Introducción. Se estudian dos casos de insensibilidad congénita al dolor que correspondían, en la clasificación de las neuropatías sensitivas autonómicas hereditarias (NSAH), a los tipos IV y V. Casos clínicos. El primer caso asociaba trastornos autonómicos muy importantes, con anhidrosis, hipertermia, lesiones tróficas cutáneas y óseas y retraso mental; el segundo sólo presentaba alteraciones muy intensas de la sensibilidad dolorosa y térmica; ambos mostraban úlceras corneales recurrentes graves. La valoración convencional neurofisiológica del sistema neuromuscular fue normal, pero en ambos casos existían anomalías en la aferencia del reflejo de parpadeo (RP); la respuesta simpática cutánea estaba abolida en el caso de la NSAH tipo IV y era normal en la NSAH tipo V. Las biopsias de nervio sural mostraban una deficiencia marcada de fibras mielínicas finas, que se asociaba a una ausencia casi completa de las amielínicas en el primer caso. Conclusiones. La alteración no descrita hasta el momento del RP en casos de insensibilidad congénita al dolor debería relacionarse con una afectación sensitiva del territorio trigeminal que, a su vez, en los casos actuales, explicaría la presencia de las úlceras corneales. El estudio del RP debería considerarse sistemáticamente en la valoración neurofisiológica de las neuropatías de fibras finas y de mediano calibre, incluso sin afectación clínica del segmento facial (AU)

Introduction. Two patients suffering from congenital insensitivity to pain were studied. They corresponded to types IV and V of the ‘hereditary sensory and autonomic neuropathies’ (HSAN) classification. Case reports. The first case showed important autonomic dysfunctions, such as anhidrosis, hyperthermia, skin and bone trophic impairment, and mental retardation; the second one only exhibited alterations in pain and temperature sensibilities. In both, chronic indolent corneal ulcers were also present. Conventional neurophysiological evaluation of the neuromuscular system was normal, but an afferent disturbance of the blink reflex (BR) was evident in both. The sympathetic skin response was absent in the HSAN type IV case and normal in the HSAN type V. Notable reduction of the small myelinated fibres, associated to almost no unmyelinated fibres in the first case, were found in the sural nerve biopsies. Conclusions. So far there haven’t been described BR abnormalities in patients with congenital insensitivity to pain, which should be related to a trigeminal sensory impairment, which could explain the corneal ulcers that suffered these cases. BR studies should be included in the neurophysiological evaluation of the suspected small fibre neuropathies even when there are no facial symptoms shown (AU)

Muerte encefálica. Valor y limitaciones diagnósticas de la electroencefalografía / Brain death. Diagnostic value and limitations of the electroencephalography

Desde que fueron enunciados los criterios de Harvard en 1968, la electroencefalografía (EEG) se ha venido utilizando como método de elección en la confirmación diagnóstica de la muerte encefálica (ME). El diagnóstico rápido y seguro de esta situación debería requerir siempre el uso de una prueba objetiva. Los criterios clínicos de la ME sólo establecen la pérdida de las funciones troncoencefálicas por lo que no es sorprendente que aproximadamente un 10 por ciento de casos en esta situación presenten actividad EEG que, muchas veces, persiste durante períodos prolongados de tiempo. El diagnóstico de la ME en neonatos y en niños de corta edad es difícil debido a la inmadurez de su sistema nerviosos central (SNC) y a sus específicas condiciones craneoencefálicas. Las principales limitaciones de la EEG se dan en los coma inducidos por fármacos depresores del SNC o en los que concurren factores tóxicometabólicos o hipotermia extrema. La EEG debe considerarse una exploración prioritaria confirmatoria del diagnóstico clínico de la ME, y en los neonatos, los niños de corta edad y los comas por lesión troncoencefálica primaria su uso debe ser obligado. Además de su alta fiabilidad, la EEG presenta muchos aspectos ventajosos sobre otros métodos diagnósticos de la ME: está disponible de manera generalizada en nuestros hospitales, es de rápida ejecución, se realiza a la cabecera del paciente, es inocua, se puede repetir sin limitaciones y es económica. La larga experiencia en su uso le da, además, un valor sociocultural añadido (AU)