Nitrogen removal performance of intermittently aerated membrane bioreactor treating black water.

The study investigated the effect of intermittent aeration on the nitrogen removal performance of a membrane bioreactor (MBR) treating black water. A pilot-scale MBR with an effective volume of 630 L operating as a sequencing batch reactor (SBR) with intermittent aeration was used in the experiments. Substrate feeding was limited to the initial non-aerated phase. The MBR unit was sustained at a steady state at a sludge age of 60 d with a biomass concentration of around 10,000 mg/L for 3 months. The treated black water could be characterized with an average COD of 950 mg/L and total nitrogen of 172 mg/L, corresponding to a low COD/N ratio of 5.5. The selected MBR scheme was quite effective, reducing COD down to 26 mg/L, providing effective nitrification and yielding a total oxidized nitrogen concentration under 10 mg N/L. The nitrogen removal performance was substantially better than the level predicted by process stoichiometry, due to multiple anoxic configuration inducing additional nitrogen removal. Dissolved oxygen profiles associated with the cyclic operation of the system suggested that the incremental nitrogen removal could be attributed to simultaneous nitrification-denitrification, a commonly observed mechanism in MBR systems sustained at high biomass concentrations.

Effect of sludge age on simultaneous nitrification and denitrification in membrane bioreactor.

This study evaluated the effect of sludge age on simultaneous nitrification and denitrification in a membrane bioreactor treating black water. A membrane bioreactor with no separate anoxic volume was operated at a sludge age of 20 days under low dissolved oxygen concentration of 0.1-0.2mg/L. Its performance was compared with the period when the sludge age was adjusted to 60 days. Floc size distribution, apparent viscosity, and nitrogen removal differed significantly, together with different biomass concentrations: nitrification was reduced to 40% while denitrification was almost complete. Modelling indicated that both nitrification and denitrification kinetics varied as a function of the sludge age. Calibrated values of half saturation coefficients were reduced when the sludge age was lowered to 20 days. Model simulation confirmed the validity of variable process kinetics for nitrogen removal, specifically set by the selected sludge age.

Effect of low dissolved oxygen on simultaneous nitrification and denitrification in a membrane bioreactor treating black water.

Effect of low dissolved oxygen on simultaneous nitrification and denitrification was evaluated in a membrane bioreactor treating black water. A fully aerobic membrane bioreactor was operated at a sludge age of 60 days under three low dissolved oxygen (DO) levels below 0.5mg/L. It sustained effective simultaneous nitrification/denitrification for the entire observation period. Nitrification was incomplete due to adverse effects of a number of factors such as low DO level, SMPs inhibition, alkalinity limitation, etc. DO impact was more significant on denitrification: Nitrate was fully removed at low DO level but the removal was gradually reduced as DO was increased to 0.5mg/L. Nitrogen removal remained optimal within the DO range of 0.15-0.35 mg/L. Experimental results were calibrated and simulated by model evaluation with the same model coefficients. The model defined improved mass transfer with lower affinity coefficients for oxygen and nitrate as compared to conventional activated sludge.

The clinical significance of HPV screening in premalignant cervical lesions.

PURPOSE: We evaluated the clinical significance of human papilloma virus (HPV) screening in premalignant cervical lesions. METHODS: This prospective study was performed at Dicle University, School of Medicine, Department of Obstetrics and Gynecology, from January 2009 to June 2009. A total of 60 cases were evaluated. Thirty cases had premalignant cervical lesions. The prevalence of HPV was analyzed by polymerase chain reaction and types determined by Hybrid Capture II. The cases that had premalignant cervical lesions were evaluated with colposcopy. Statistical analyses were carried out by using the statistical packages for SPSS version 12.0 for Windows (Chicago, IL, USA). RESULTS: Of all the cases, those with premalignant cervical lesions had higher prevalence of HPV DNA. The cases that had high oncogenic HPV type had more abnormal colposcopic findings. CONCLUSION: Premalignant cervical lesions should be evaluated by cervical cytology, colposcopy, HPV DNA screening and cervical tissue sampling. In this way, development of cervical cancer can be prevented.

Prevalence of atopy in rheumatoid arthritis in Sivas, Turkey. A prospective clinical study.

Assumed mutual antagonism of T-helper cell (Th)1 and Th2 diseases suggests that the prevalence of atopy should be decreased in rheumatoid arthritis (RA). We tried to determine that prevalence. Sixty-two patients with RA and 61 with osteoarthritis (control group) were included in the study. A questionnaire was used concerning mainly the symptoms of atopy. Skin prick tests, pulmonary function tests, chest X-rays, immunoglobulin E levels, and eosinophil counts were obtained. The prevalences of asthma, hay fever, and eczema in the RA group were 3.2%, 14.5%, and 1.6%, respectively. In the control group, they were 6.5%, 22%, and 6.5%, respectively. There was no significant difference between groups. There was also no significant difference between immunoglobulin E levels. Eosinophil counts were higher in the control group, however these values were within the normal range. Skin prick tests were obtained in seven RA patients, and eight controls revealed increased positivity. The prevalence of atopy in rheumatoid arthritis was not different from that in the general population. Our study results cannot support the concept of Th1/Th2 mutual antagonism.

[Treatment plans and results in iatrogenic ureteral injuries]. / Iatrojenik üreteral travmalarda tedavi planlarimiz ve sonuçlari.

We treated 19 patients with iatrogenic ureteral injuries during a 10-year period. Gynecological operations were the most common surgical procedures (52.6%). The diagnosis of ureteral injury was made immediately in 6 patients and was delayed 14 to 180 days in 13. Five of the 6 injuries recognized during the operation were repaired successfully at the time of injury; one patient resulted a nephrectomy. Seven of the lately recognized 13 patients were treated with percutaneous nephrostomy and the first treatment. The two patients were made ureteroneocystostomy, one was made ureteroureterostomy and one had ureterolysis in the other five patients. We observed ureteral stenosis in the three patients after the operation follow ups. The treatment was achieved with the endourological approach at these patients. Finally, we recommend percutaneous nephrostomy as a first treatment choice in the lately recognized iatrogenic ureteral injuries, while the immediate diagnosis and treatment of iatrogenic ureteral injuries, are severely important.