A potential application of sludge-based catalysts for the anaerobic bio-decolorization of tartrazine dye.

Two highly efficient (K2CO3/sludge carbon and ZnCl2/sludge carbon) solids were prepared by chemical addition following carbonization at 800 °C and were tested for anaerobic reduction of tartrazine dye in a continuous upflow packed-bed biological reactor, and their performance was compared to that of commercial activated carbon (CAC). The chemical and structural information of the solids was subjected to various characterizations in order to understand the mechanism for anaerobic decolorization, and efficiency for SBCZN800 and SBCPC800 materials was 87% and 74%, respectively, at a short space time (τ) of 2.0 min. A first-order kinetic model fitted the experimental points and kinetic constants of 0.40, 0.92 and 1.46 min(-1) were obtained for SBCZN800, SBCPC800 and CAC, respectively. The experimental results revealed that performance of solids in the anaerobic reduction of tartrazine dye can depend on several factors including chemical agents, carbonization, microbial population, chemical groups and surface chemistry. The Langmuir and Freundlich models are successfully described in the batch adsorption data. Based on these observations, a cost-effective sludge-based catalyst can be produced from harmful sewage sludge for the treatment of industrial effluents.

Tooth loss, chewing efficiency and cognitive impairment in geriatric patients.

BACKGROUND Patients with dementia have poorer oral health and fewer teeth than their peers without cognitive impairment. OBJECTIVE The hypothesis of this study is that the number of natural teeth and the chewing efficiency are associated with cognitive functioning. METHODS This cross-sectional study included 29 patients diagnosed with dementia aged 75 years or older and 22 controls who were either cognitively normal (n = 19) or with mild cognitive impairment (n = 3). Neuropsychological, nutritional and dental assessments were performed. The chewing efficiency was evaluated with a two-colour mixing test. RESULTS Demented patients and controls presented with a mean of 4.9 and 6.5 teeth, respectively (n.s.). The number of natural teeth was not associated with dementia (p = 0.553). Same results were found for age (p = 0.746) and sex (p = 0.901). The chewing efficiency by visual inspection proved worse in participants with dementia than in the controls (p < 0.011) and explained 9.3% of the variance in the diagnosis of dementia. Neither dental state nor chewing efficiency was related to the nutritional state. CONCLUSION Chewing efficiency seems stronger associated with cognitive impairment than the number of teeth. Hence, in a more holistic approach for the geriatric assessment, the dental examination may be complemented by a chewing efficiency test.