Effect of ultrasound pre-treatment in the anaerobic co-digestion of cattle manure with food waste and sludge.

This paper presents a study of the effect of applying ultrasound pre-treatment in the production of methane when co-digesting mixtures of cattle manure with food waste and sludge. A series of experiments were carried out under mesophilic and thermophilic conditions in continuously stirred-tank reactors containing 70% cattle manure, 20% food waste and 10% sewage sludge. Ultrasound pre-treatment allows operating at lower HRT, achieving higher volumetric methane yields: 0.85 L CH4/L day at 36°C and 0.82 CH4/L day at 55°C, when cattle manure and sewage sludge were sonicated. With respect to the non-sonicated waste, these values represent increases of up to 31% and 67% for mesophilic and thermophilic digestion, respectively.

Removal of residual phenols from coke wastewater by adsorption.

After biological treatment, coke wastewater contains small amounts of phenolic compounds resistant to such treatment. The removal of phenols and COD from coke wastewater subjected to biological treatment was studied. The adsorbents used were granular activated carbon and the resins XAD-2, AP-246 and OC-1074. Equilibrium, kinetics and column assays were carried out, fitting the equilibrium data to Langmuir and Freundlich models and the kinetic data to the Lagergren equation. The best results were obtained with GAC, which presented higher adsorption capacities. In the equilibrium assays, the adsorption capacities (Q) found were 1.48 mg g(-1) for GAC versus 0.07 and 0.04 mg g(-1) for resins AP-246 and OC-1074, respectively. In the kinetic assays, the values of the Lagergren adsorption parameter, q(e), were 1.69, 0.15 and 0.14 mg g(-1) for GAC, AP-246 and OC-1074, respectively. In the column assays, the dynamic capacity of GAC for up to 480 bed volumes was 1.82 mg mL(-1). No saturation was obtained for this volume due to the asymptotic shape of the breakthrough curve, whereas for the same percolated volume, the resins AP-246 and OC-1074 were saturated. These two resins presented similar saturation capacities of around 1.1 mg mL(-1).

Extraction wells and biogas recovery modeling in sanitary landfills.

A general methodology is established that permits the characterization and evaluation of the optimum potential of biogas extraction at each vertical well in the sanitary landfill of Asturias, Spain. Twenty wells were chosen from a total of 225 for the study, and the maximum production flow of biogas, which is a result of the degradation of the municipal solid waste deposited within its area of influence, was determined for each well. It was found that this flow varied with time and is characteristic of each extraction well. The maximum extractable flow also was determined as a function of the composition of the biogas needed for its subsequent utilization. The biogas extraction yield in the wells under study varied between approximately 26 and 97%, with a mean recovery value of 82%. The low yields found in certain cases were generally caused by a sealing defect, which leads to excessive incorporation of air into the landfill gas through the surrounding soil or through the extraction shaft, and which make its subsequent utilization difficult.

[Diagnosis and treatment of cervical esophageal perforation in adults]. / Diagnóstico y tratamiento de las perforaciones de esófago cervical en adultos.

OBJECTIVE: To evaluate the management of cervical esophageal perforation in adult patients. MATERIAL AND METHODS: A retrospective clinical review was made of all cervical esophageal perforations diagnosed in adult patients in the ear, nose and throat department of Marqués de Valdecilla Hospital (Santander, Spain) between January 1989 and December 1996. Age, sex, symptoms, cause of perforation, time to diagnosis, diagnostic studies, treatment, and evolution were obtained from the clinical records. RESULTS: Eleven patients with perforation of the cervical esophagus, age range 38 to 84 years, were seen in the study period. In 8 cases, perforation was caused by a foreign body and 3 cases were iatrogenic (after rigid esophagoscopy). The most frequent symptoms of presentation were cervical pain and odinophagia. Nine patients were treated with broad-spectrum intravenous antibiotic therapy and no oral feeding. Two patients were treated surgically. There were no complications or need for further surgery in any case. CONCLUSIONS: Small perforations of the cervical esophagus in adult patients produced by foreign body impaction or rigid esophagoscopy can be managed by observation, restricted oral intake, and intravenous antibiotics. Neck exploration should be reserved for patients with signs and symptoms of cervical or mediastinal infection.

[Foreign bodies in the esophagus]. / Cuerpos extraños de esófago.

OBJECTIVE: To study the management (diagnostic and therapeutic) of esophageal foreign bodies. MATERIAL AND METHODS: A retrospective study was made of all rigid esophagoscopies performed for suspected foreign bodies in the esophagus by the otolaryngology department of Marqués de Valdecilla Hospital (Santander, Spain) from 1992 to 1996. RESULTS: Rigid esophagoscopy was performed for suspected foreign bodies in 195 patients (121 females, 74 males; age range 2 to 97 years). In 183 cases an impacted foreign body was found. The most frequent location was the upper third of the esophagus (165/85.2%). The most common type of foreign body was fish bones in adults (75/171) and coins in children (7/12). In 145 cases a barium esophagogram was obtained before surgery, which yielded 1 false negative and 8 false positives. In 16 patients flexible endoscopy had failed previously to remove the foreign body. Twelve patients (all adults) had serious complications. CONCLUSIONS: The barium esophagogram and rigid esophagoscopy are still appropriate techniques for managing esophageal foreign bodies.

Laryngeal melanosis: report of four cases and literature review.

OBJECTIVE: Laryngeal melanosis is a rare condition defined by the presence of melanocytes within the laryngeal epithelial lining. Our aims were (1) to review our cases together with those in the literature, and (2) to determine whether melanocyte incidence is increased with exposure to irritant stimuli such as tobacco. METHODS: A retrospective study of all cases diagnosed with laryngeal melanosis in our hospital from January 1, 1990, to December 31, 1996, was accomplished. To determine the melanocyte incidence in the normal larynx as well as the influence of tobacco in development of laryngeal melanosis, 16 age-matched controls, 8 of whom were smokers and 8 of whom were not, were chosen, and a histochemical and immunohistochemical study was performed. The following antibodies were used: S-100 protein, CD1a, and HMB-45. A comparative study of the melanocyte incidence between patients with laryngeal melanosis and the controls was carried out. Also, a comparative study between smoking and nonsmoking patients was performed. RESULTS: Laryngeal melanosis was diagnosed in 4 patients at our hospital during this period of time. In the comparative study, the number of melanocytes in the 4 patients with laryngeal melanosis was higher than in the 8 smoking (p < 0.01, Mann-Whitney U test) and 8 nonsmoking (p < 0.01) controls, and there was a trend toward a higher number of melanocytes in the 8 smoking patients than in the 8 nonsmoking (p = 0.064) controls. CONCLUSIONS: Laryngeal melanosis was more frequent in smoking men older than 50 years. Our observations underline the association of LM with larynx carcinoma and its relation to a stimulus such as tobacco. In fact, we have found activated melanocytes in our cases of laryngeal melanosis. They were identified by immunoreactivity for HMB-45.