UV disinfection of wastewater effluents for unrestricted irrigation.

Wastewater reuse in arid regions is important for the production of a water resource to be utilised for non-potable purposes and to prevent the environmental transmission of disease-causing agents. This study was conducted to evaluate the effect of water quality on the comparative disinfection efficiency of viruses, bacteria and spores by UV irradiation. Furthermore, the microbial quality of effluent produced by coagulation, high rate filtration (HRF) and either UV irradiation or chlorination was determined. Using low pressure collimated beam, a UV dose of 80 mWs/cm2 was needed to achieve a 3-log10 inactivation of either rotavirus SA-11 or coliphage MS2, whereas over 5-log10 inactivation of E. coli was reached with a dose of only 20 mWs/cm2. B. subtilis inactivation was found to be linear up to a dose of 40 mWs/cm2 and then a tailing up to a UV dose of 120 mWs/cm2 was observed. It is worth noting that effluent turbidity of < 5 NTU did not influence the inactivation efficiency of UV irradiation. Operation of a pilot plant to treat secondary effluent by coagulation, HRF and UV disinfection at a UV dose of 80 mWs/cm2 resulted in the production of high quality effluent in compliance with the Israel standards for unrestricted irrigation (< 10 CFU/100 mL faecal coliform and turbidity of < 5 NTU). Sulphite reducing clostridia (SRC) were found to be more resistant than coliphages and F coliform for UV irradiation. The results of this study indicated that UV disinfection is suitable for the production of effluents for unrestricted irrigation of food crops.     

Test anxiety and ineffective test taking: Different names, same construct?

Investigated the relative contributions of test anxiety and exam-taking skills to information-processing deficits in a dual-task paradigm. Under stress instructions, 64 high- and low-test-anxious college students with either good or poor exam-taking skills alternately performed a primary task (Raven Advanced Progressive Matrices) separately and concurrently with a secondary task (a backward digit span test). Results indicate that exam-skilled, high-anxious Ss performed comparably with skilled, low-anxious peers on the primary Raven task, yet significantly worse on the concurrent backward digit span task. Conversely, high-anxious, unskilled Ss were exceeded by low-anxious, unskilled peers on both tasks. Findings suggest that test anxiety and exam-taking ability independently influence cognitive problem solving in the evaluative setting. It is suggested that although good exam skills can compensate for anxiety-induced deficits in working-memory capacity by refocusing attention toward the task, processing deficits still emerge as task demands increase. Measures of state anxiety and cognitive interference further suggest that a negative internal focus, not arousal, underlies such deficits. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)