Modelling PAHs removal in activated sludge process: effect of disintegration.

The removal of polycyclic aromatic hydrocarbons (PAHs) in activated sludge was evaluated using two laboratory-scale bioreactors, coupled or not with a disintegration system (sonication). Mass balances performed on each system underlined that PAHs removal was significantly improved after sludge disintegration, especially for the higher molecular weight PAHs studied, which tended to adsorb to suspended matter. A model was developed in order to study the effect of sludge disintegration on the content of dissolved and colloidal matter (DCM), and to predict the potential impacts on PAHs availability and degradation. Results showed that this new model was efficient for capturing apparent degradation improvement trends and for discriminating between the involved mechanisms. This study showed that DCM content increased after sludge disintegration, and proved to be the main driver for improving PAHs apparent degradation.

Epidemiology, molecular characterisation and antimicrobial susceptibility of Neisseria gonorrhoeae isolates in Madrid, Spain, in 2016.

With the aim to elucidate gonococcal antimicrobial resistance (AMR)-risk factors, we undertook a retrospective analysis of the molecular epidemiology and AMR of 104 Neisseria gonorrhoeae isolates from clinical samples (urethra, rectum, pharynx and cervix) of 94 individuals attending a sexually transmitted infection clinic in Madrid (Spain) from July to October 2016, and explored potential links with socio-demographic, behavioural and clinical factors of patients. Antimicrobial susceptibility was determined by E-tests, and isolates were characterised by N. gonorrhoeae multi-antigen sequence typing. Penicillin resistance was recorded for 15.4% of isolates, and most were susceptible to tetracycline, cefixime and azithromycin; a high incidence of ciprofloxacin resistance (~40%) was found. Isolates were grouped into 51 different sequence types (STs) and 10 genogroups (G), with G2400, ST5441, ST2318, ST12547 and G2992 being the most prevalent. A significant association (P = 0.015) was evident between HIV-positive MSM individuals and having a ciprofloxacin-resistant strain. Likewise, a strong association (P = 0.047) was found between patient age of MSM and carriage of isolates expressing decreased susceptibility to azithromycin. A decrease in the incidence of AMR gonococcal strains and a change in the strain populations previously reported from other parts of Spain were observed. Of note, the prevalent multi-drug resistant genogroup G1407 was represented by only three strains in our study, while the pan-susceptible clones such as ST5441, and ST2318, associated with extragenital body sites were the most prevalent.

Modelling PAH partitioning during sludge disintegration: The key role of dissolved and colloidal matter.

The partitioning between solids and the aqueous phase largely controls the fate of PAH compounds in biological treatment. The prediction of PAH sorption behaviour into activated sludge was investigated here. The suitability of a three-compartment model to describe partitioning in such a complex matrix was first evaluated by adding increasing quantities of dissolved and colloidal matter (DCM) (from 0 to 34.9% of the total matter). In a range of DCM concentrations varying from 0 to 1.4 g L-1, the PAH aqueous fraction, including both freely dissolved and sorbed to DCM molecules, increased from 9.9% to 33% for naphthalene (the most soluble PAH) and from 0.29% to 13.3% for indeno(1,2,3,c,d)pyrene (the least soluble PAH tested). The sorption of PAHs on dissolved and colloidal matter (DCM) was assessed by determining two partitioning constants (KPART and KDCM) for the 16 PAHs listed by the US EPA. New experiments were carried out for model validation and show that the model properly predicts the PAH partitioning following sludge disintegration by sonication.

Enrichment and adaptation yield high anammox conversion rates under low temperatures.

This study compared two anammox sequencing batch reactors (SBR) for one year. SBRconstantT was kept at 30 °C while temperature in SBRloweringT was decreased step-wise from 30 °C to 20 °C and 15 °C followed by over 140 days at 12.5 °C and 10 °C. High retention of anammox bacteria (AnAOB) and minimization of competition with AnAOB were key. 5-L anoxic reactors with the same inoculum were fed synthetic influent containing 25.9 mg NH4+-N/L and 34.1 mg NO2--N/L (no COD). Specific ammonium removal rates continuously increased in SBRconstantT, reaching 785 mg NH4+-N/gVSS/d, and were maintained in SBRloweringT, reaching 82.2 and 91.8 mg NH4+-N/gVSS/d at 12.5 and 10 °C respectively. AnAOB enrichment (increasing hzsA and 16S rDNA gene concentrations) and adaptation (shift from Ca. Brocadia to Ca. Kuenenia in SBRloweringT) contributed to these high rates. Rapidly settling granules developed, with average diameters of 1.2 (SBRconstantT) and 1.6 mm (SBRloweringT). Results reinforce the potential of anammox for mainstream applications.

Dynamic modeling of biodegradation and volatilization of hazardous aromatic substances in aerobic bioreactor.

The aerobic biological process is one of the best technologies available for removing hazardous organic substances from industrial wastewaters. But in the case of volatile organic compounds (benzene, toluene, ethylbenzene, p-xylene, naphthalene), volatilization can contribute significantly to their removal from the liquid phase. One major issue is to predict the competition between volatilization and biodegradation in biological process depending on the target molecule. The aim of this study was to develop an integrated dynamic model to evaluate the influence of operating conditions, kinetic parameters and physical properties of the molecule on the main pathways (biodegradation and volatilization) for the removal of Volatile Organic Compounds (VOC). After a comparison with experimental data, sensitivity studies were carried out in order to optimize the aerated biological process. Acclimatized biomass growth is limited by volatilization, which reduces the bioavailability of the substrate. Moreover, the amount of biodegraded substrate is directly proportional to the amount of active biomass stabilized in the process. Model outputs predict that biodegradation is enhanced at high SRT for molecules with low H and with a high growth rate population. Air flow rate should be optimized to meet the oxygen demand and to minimize VOC stripping. Finally, the feeding strategy was found to be the most influential operating parameter that should be adjusted in order to enhance VOC biodegradation and to limit their volatilization in sequencing batch reactors (SBR).

Fate of hazardous aromatic substances in membrane bioreactors.

In this work, the removal of hazardous aromatic compounds was investigated in two types of membrane bioreactors (MBRs), based on cross-flow and semi dead-end filtration systems. BTEX and PAH were efficiently eliminated from wastewater during treatment via a membrane bioreactor (90-99.9%) but non-biotic processes, i.e. volatilisation and sorption, contributed significantly. The semi dead-end MBR showed slightly better removal efficiencies than the cross-flow MBR. However, non-biotic processes were more significant in the first process and, finally, degradation rates were higher in the cross-flow MBR. Higher degradation rates were explained by a higher bio-availability of pollutants. Differences in shear stress imposed in cross-flow and semi dead-end filtration systems radically modify the sludge morphology. High shear stress (cross-flow filtration) generates dispersed bacteria and larger quantities of dissolved and colloidal matter. Sorption of hydrophobic compounds (PAHs) on suspended solid was less marked in disaggregated sludge. The results suggest new strategies for improving micro-pollutant degradation in MBRs.

[Treatment with nebulized lidocaine in steroid-dependent asthma]. / Tratamiento con lidocaína nebulizada del asma corticodependiente.

BACKGROUND: The management of glucocorticoid dependent and resistant asthma encompasses a group of problems, affecting as much control of clinical symptoms as the onset of adverse effects to prolonged use of steroids. MATERIALS AND METHODS: Woman 52 years old, steroid dependent asthma fifteen years ago. She has important adverse effects in consequence of the use of systemic glucocorticoids. The employment of methotrexate attained decrease in the dosage of steroids temporarily. The worsening of the clinical situation and deterioration of secondary effects by use of steroids necessitated treatment with nebulized lidocaine. A 2% solution to initial dosage was administered three times daily. The maximal dosage needed was 80 mg three times daily. RESULTS: After three months of lidocaine treatment, the patient was able to reduce oral steroids eventually discontinuing these drugs, and the effects secondary to exogenous hypercortisolism disappeared. Moreover, an improvement in clinical symptoms and quality of life was observed with stability in the pulmonary function. CONCLUSIONS: The use of nebulized lidocaine could be useful and provide alternatives in patients with severe asthma.

Tratamiento con lidocaína nebulizada del asma corticodependiente / Treatment with nebulized lidocaine to steroid-dependent asthma

Antecedentes: El cuidado de los pacientes con asma bronquial corticodependiente y corticorresistente supone un conjunto de problemas, que afectan tanto a la situación clínica como al desarrollo de efectos adversos secundarios a una prolongada terapia esteroidea. Material y métodos: Mujer de 52 años con asma corticodependiente de 15 años de evolución con manifestaciones clínicas de hipercortisolismo. El uso de metotrexato oral consiguió un descenso transitorio en las dosis de esteroides. El agravamiento de la situación clínica obligó a un aumento de las dosis de esteroides con el consiguiente empeoramiento de los efectos secundarios. Por este motivo se instauro tratamiento con lidocaína nebulizada al 2 % a dosis iniciales de 40 mg cada 8 horas hasta una dosis máxima de 80 mg cada 8 horas. Resultados: Tras 3 meses de tratamiento con lidocaína nebulizada se reducen las dosis de corticoides orales hasta la suspensión total de estos con la desaparición o mejoría de los efectos secundarios al hipercortisolismo. Se produjo una mejoría en su situación clínica así como un aumento en la calidad de vida de la paciente con estabilidad en los parámetros de función pulmonar. Conclusiones: El uso de lidocaína nebulizada podría representar una alternativa eficaz y segura en el tratamiento del asma de difícil manejo

Background: The management of glucocorticoid dependent and resistant asthma compases a group of problems, So much control of clinical symptoms and onset of adversa effects to prolongad use of steroids. Materials and methods: Woman 52 years cid, steroid dependent asthma fifteen years ago. She was important adversa effects in consecuence the use sistemic glucocorticoids. The employment of metotrexate attained decrease in the dosage of steroids temporally. The wrong of clinical situation and deterioration secondary effects by use of steroids maked to start treatment with nebulized lidocaine of a 2 % solution to initial dosage was a three times daily. The maximal dosage needy was made of 80 mg three times daily. Results: After three months of beginning from lidocaine treatment, patient obtained to reduce orally steroid up to discontinuance or these drugs and the effects secondary to exogenous hypercortisolism disappeared. Moreover, A improvement in clinical symptoms and quality of lita was observad with stability in the pulmonary function. Conclusions: The use of nebulized lidocaine could be a useful and gafe alternativa in patients with severa asthma