Effect of photochemical pre-treatment on COD fractionation of a non-ionic textile surfactant.

The work presented in this paper is focused on the effect of photochemical (H2O2/UV-C) pretreatment on COD fractionation and degradation kinetics of a non-ionic textile surfactant. In the first part of the study, the COD of non-ionic surfactant was adjusted to 1000 mg/L in order to simulate real effluent originating from the textile preparation stage featuring desizing, scouring, washing and rinsing operations. The surfactant was subjected to H2O2/UV-C pretreatment for up to 120 min at a dose of 30 mM (980 mg/L) H2O2. The biodegradability studies for untreated and photochemically treated samples were evaluated on the basis of modeling of oxygen uptake rate (OUR) profiles. Modelling of OUR profiles conducted for untreated sample showed that single complex substrate was subjected to enzymatic breakdown and disintegrated into one readily and two types of slowly biodegradable substrates. After modelling the biodegradation of photochemically pretreated sample, the readily biodegradable COD fraction was reduced, on the other hand, more slowly biodegradable organics were generated. A higher disintegration rate was obtained for chemically pretreated samples. However, other kinetic constants of growth and hydrolysis processes were not affected considerably.

Nitrogen recovery by urea hydrolysis and struvite precipitation from anthropogenic urine.

Human urine is a source of nutrients and has a significant potential for recycle of nitrogen. Recently, much research focused on separate collection and treatment of human urine. Recovery of nutrients from human urine requires hydrolysis of urea into ammonia and subsequent removal of ammonia and sometimes phosphorus. This study attempted to evaluate urea hydrolysis of human urine in both untreated fresh samples and urease added urine samples. Recovery of nutrients by struvite precipitation on pre-hydrolysed samples was also assessed on undiluted and 1:1 diluted samples. Results of urea hydrolysis on untreated urine samples indicated that the process was slow and pH exerted a significant effect on the process. No hydrolysis occurred above pH 10. From pH 2 to 7.5, 25% of urea could be hydrolysed in 30 d. Urease added hydrolysis with the enzyme doses 25-49 mg L(-1) was a rapid process providing complete conversion into ammonia in 1.5 h. Struvite precipitation conducted on enzyme hydrolysed urine sample proved to be an efficient process and ammonia removals up to 95% were obtained. Struvite precipitation also provided 50% organic nitrogen removal.

Perlite exposure and 4-year change in lung function.

Perlite is a volcanic glass or amorphous aluminium silicate composed of 71-75% SiO(2). When heated to 800-1100 degrees C, it expands to form processed perlite, which has a low density, high surface area, and a low thermal conductivity. The objective was to determine the effect of perlite exposure on pulmonary function tests. Pulmonary function tests in conjunction with chest radiogram were carried out in 36 perlite-exposed workers and 22 unexposed office workers in 1992 and 1996. Respirable dust level exceeded permissible dust levels in work places in the 4 years under study. Transfer coefficient (K(CO)) decline was significant in nonsmoker perlite-exposed workers (n=9), and found to be 5.28+/-0.71 (predicted 4.32+/-0.11) and 3.84+/-0.96 (predicted 4.18+/-0.18) 1/min/mmHg, in 1992 and 1996, respectively (P<0.001). Both smoker perlite workers and office workers showed significant obstruction to airflow in small airways with respect to predicted values and 4-year change in transfer factor (T(L), CO) was significant. Although predicted, 12-year perlite exposure did not lead to a decrease in mean pulmonary function test parameters, there was a tendency to a decline in T(L), CO in the 4-year study period, which may be due to high perlite dust levels. As early effects of perlite dust exposure may not be detected by spirometric measurements alone, the transfer coefficient should be added to spirometry.

The value and limitations of 201Tl scintigraphy in the evaluation of lung lesions and post-therapy follow-up of primary lung carcinoma.

In this study 201Tl planar scintigraphy and single photon emission computed tomography (SPECT) were performed in 92 patients with solitary lung lesions in order to distinguish malignant versus benign and metastatic masses and to evaluate the radiotherapy response of 15 primary lung carcinomas. Semiquantitative and quantitative analyses were carried out and the results were compared with histopathological diagnosis. The overall sensitivity, specificity and accuracy of semiquantitative analysis were 56, 71 and 58%, and quantitative evaluations were 88.8, 100 and 92%, respectively. Retention indexes (RI) derived from the early and delayed images were 2.9 +/- 1.3 for primary lung carcinomas, -2.78 +/- 0.9 for benign conditions and -2.3 +/- 1.5 for metastatic pulmonary lesions. 201Tl scintigraphy seems to be a sensitive modality for differentiating malignancies from benign conditions since the difference between those two pathologies is significant. However, this procedure has a limited value in distinguishing metastatic pulmonary lesions from benign pathologies, and in tissue characterization of primary lung carcinomas. On the other hand, a good correlation was observed between 201Tl lung scintigraphy and clinical diagnostic examination during postradiotherapy follow-up of inoperable pulmonary neoplasia.