Dynamic modeling of nutrient removal by a MBR operated at elevated temperatures.

The process performance of a MBR operated on municipal sewage at elevated temperatures was evaluated by dynamic modeling. The enhanced biological phosphorus removal (EBPR) performance varied from 40% to 95% with process temperature ranging from 24 to 38 °C. The respective maximum substrate uptake rate (qPHA) was estimated at 1.5 gCODS/gCODX.day-1 for Glycogen Accumulating Organisms (GAO) and 4.7 gCODS/gCODX.day-1 for Phosphate Accumulating Organisms (PAO) with Arrhenius coefficients (θ) for GAOs and PAOs of 1.06 and 1.04 respectively. With these parameters the effluent PO4 levels of the MBR operated for 450 days could be well described. In addition, the impact of mesophilic conditions and low influent P/VFA levels on GAO proliferation was evaluated under dynamic process conditions. Nitrification process was temporarily impaired at high temperatures around 38 °C. Simulations revealed that the contribution of the anoxic reactor to the total overall denitrification was limited to 40%The contribution of simultaneous nitrification and denitrification (SNdN) process to the denitrification was around 40-50% depending upon dissolved oxygen levels in aerobic and MBR tanks. The large contribution of SNdN was due to gas/liquid mass transfer limitation conditions mediated by high mixed liquor viscosities (20-35 mPa.S) in MBR system. The membrane flux was 43 L/m2/h corresponding to the specific permeability (K) of 413 L/m2/h/bar at 38 °C.

Long-term study on the impact of temperature on enhanced biological phosphorus and nitrogen removal in membrane bioreactor.

The study involved experimental observation and performance evaluation of a membrane bioreactor system treating municipal wastewater for nutrient removal for a period 500 days, emphasizing the impact of high temperature on enhanced biological phosphorus removal (EBPR). The MBR system was operated at relatively high temperatures (24-41 °C). During the operational period, the total phosphorus (TP) removal gradually increased from 50% up to 95% while the temperature descended from 41 to 24 °C. At high temperatures, anaerobic volatile fatty acid (VFA) uptake occurred with low phosphorus release implying the competition of glycogen accumulating organisms (GAOs) with polyphosphate accumulating organisms (PAOs). Low dissolved oxygen conditions associated with high wastewater temperatures did not appreciable affected nitrification but enhanced nitrogen removal. Dissolved oxygen levels around 1.0 mgO2/L in membrane tank provided additional denitrification capacity of 6-7 mgN/L by activating simultaneous nitrification and denitrification. As a result, nearly complete removal of nitrogen could be achieved in the MBR system, generating a permeate with no appreciable nitrogen content. The gross membrane flux was 43 LMH corresponding to the specific permeability (K) of 413 LMH/bar at 39 °C in the MBR tank. The specific permeability increased by the factor of 43% at 39 °C compared to that of 25 °C during long-term operation.

Resection of endobronchial hamartoma causing recurrent hemoptysis by electrocautery and cryotherapy.

BACKGROUND: Pulmonary hamartomas are rare benign tumors of the lung with an incidence of 0.025%-0.32%. Endobronchial benign lesions can cause bronchial obstruction and recurrent respiratory infections or obstructive pneumonia and recurrent hemopthysis. CASE REPORT: A 66-year-old male with recurrent hemoptysis and pneumonias for a year, was referred to our department for an endoscopic resection of an endobronchial hamartoma. Initially he refused any intervention but, as he suffered additional episodes of hemoptysis and chest infections during a year on follow up, he finally underwent interventional bronchoscopy and the lesion was cauterized using snare electrocautery probe and removed with cryoextraction. The patient has been followed for two years in our outpatient clinic, with no further problems. CONCLUSION: Endoscopic treatment with flexible bronchoscope, electrocautery and cryotherapy provides an excellent outcome. Surgical therapy, should be reserved for the hamartomas that cannot be approached through endoscopy. Hippokratia 2014; 18 (4): 355-356.

Visceral injuries, wound infection and sepsis following electrical injuries.

Visceral injuries, wound infection and sepsis were investigated in 226 inpatients who sustained electrical burns over a period of 15 years. Four patients who sustained thoracic and abdominal organ injuries were noted in this series. The patients had injuries of the small intestine, stomach, colon and the lung. All the patients received operative treatment. Two of them died of sepsis. Injuries to the internal organs should always be considered following high-voltage injuries, and they should be managed as early as possible. The data concerning wound infection and sepsis following electrical injuries were evaluated in three consecutive 5-year periods. Over this period of 15 years, different antibiotic regimens were used for prophylaxis and treatment. Most patients in the current series had been contaminated or infected by various pathogens prior to admission. Long-lasting administration of prophylactic antibiotics in these patients showed no improvement in controlling the sepsis. After 1987, most of the microorganisms were eliminated following more effective antimicrobial therapy. The progressive decrease in infection frequency of species such as Pseudomonas aeruginosa, Proteus mirabilis and Enterobacter cloacae, appeared to be causally related to the changes in the general therapeutic protocol which included new antibiotics. The infections caused by E. coli and Staphylococcus aureus showed a rather steady state. A marked increase in frequency of negative wound cultures was also noted between the years 1989 and 1993. A gradual decrease in mortality rates was observed from the first to the last 5-year period, whereas mortality rates due to sepsis showed a gradual but slower decline. Sepsis (142 patients comprising 62.8 per cent of the total mortality rate) was the most frequent complication resulting in death.

Epidemiological survey of burns treated in Ankara, Turkey and desirable burn-prevention strategies.

From 1 January 1979 to 31 December 1993, 1109 patients were admitted to our burn unit located at Hacettepe University. Of the patients, 638 (57.5 per cent) were children (under the age of 16 years). The male to female ratio was 1.4:1 in children, and was approximately 2.6:1 for patients over 16 years of age. Of the 638 paediatric patients, 67 (10.5 per cent) sustained electrical burns. The causes of injury in the remaining 571 cases (89.5 per cent) were hot liquids in 379 (66.4 per cent of the non-electrical burns), flame in 190 (33.3 per cent) and contact burns in two (0.3 per cent). Of the scalds, 296 (78.1 per cent of the scalds), 52 (13.7 per cent), 22 (5.8 per cent) and nine (2.4 per cent) were caused by hot water, milk, meal and oil respectively. Of the flame burns, 21 (11.1 per cent) were due to LPG explosions. Of the 471 adult patients (over 16 years), 159 (33.8 per cent) were injured by electricity. The causes of non-electrical burn injuries were: hot liquid in 25, flame in 274, chemical agents in four, contact in four, and other causes in four. Although our centre is located in Central Anatolia, 41.8 per cent of all patients were referred from the other six regions of Turkey. Of the 1109 inpatients, 645 (58.2 per cent) were injured in Central Anatolia, 279 (25.2 per cent) in the Black Sea Region, 55 (5.0 per cent) in the Mediterranean Region, 18 (1.6 per cent) in the Marmara Region, 34 (3.1 per cent) in the Aegean Region, 52 (4.7 per cent) in Southeastern Anatolia and 26 (2.3 per cent) in Eastern Anatolia. Approximately two-thirds of the patients (419) required one or more surgical interventions, including debridement and grafting, as well as amputation. The most important early complications were acute renal failure (148 patients - 13.3 per cent), sepsis (660 patients - 59.5 per cent) and gastrointestinal haemorrhage (seven patients - 0.6 per cent). The overall mortality rate was 34.4 per cent. The epidemiological pattern of the burns showed that emergency measures should be taken to prevent scalding accidents to children throughout the country, and for electrical burns in adults, particularly those living in the Black Sea Region. In establishing, implementing and directing prevention programmes, regional differences should be taken into consideration.