Performance evaluation of novel PVDF-Cloisite 15A hollow fiber composite membranes for treatment of effluents containing dyes and salts using membrane distillation

The present study reports the performance of a novel PVDF-Cloisite 15A hollow fiber composite membrane for the treatment of effluents containing dyes and salts through a direct contact membrane distillation (DCMD) process. The performance of the membrane was evaluated by varying several important parameters during the DCMD process which included feed properties (type of dyes, dye and salt concentration) and process conditions (feed temperature and flow rate). The experimental results showed that the in-house made membrane was able to achieve stable fluxes and excellent dye rejections (>97%) when tested with feed solutions containing dyes of different classes and molecular weights (MW), except crystal violet (CV) dye. The lower rejection resulting from a CV-containing feed is likely due to its small MW coupled with its high diffusion rate in aqueous solution. With respect to feed concentration, it is found that an increase in salt concentration in the feed solution had a negligible effect on the membrane separation performance. Increasing the dye concentration in the feed however led to lower membrane water flux owing to the deposition of dye particles on the membrane surface which resulted in severe fouling. Meanwhile, increasing the feed temperature and its flow rate could improve the membrane flux without affecting the permeate quality. When tested using a dyeing solution containing 50 ppm acid red and 1.0 M NaCl, the membrane flux was reported to enhance by 200% and 25% on increasing the feed temperature from 50 to 90 °C and the flow rate from 0.010 to 0.023 m s-1, respectively

Childhood health as reflected in adult urban and rural samples from medieval Denmark

This study examines the evidence of three skeletal markers relating to childhood health that leave permanent observable changes in the adult skeleton. Two are well known to paleopathology, namely Harris lines (HL) and linear enamel hypoplasia (LEH). The third skeletal marker is less commonly used; the permanent changes in the temporal bones, induced by chronic or recurrent infectious middle ear disease (IMED) in childhood. A total of 291 adult skeletons from an urban (n = 109) and a rural (n = 182) cemetery, from the Danish medieval period (1050–1536 CE) were included. The markers were examined for their co-occurrence, and differences between the two samples. No statistically significant difference for the three skeletal markers between the two samples was found. A trend was nevertheless apparent, with greater frequencies for all three skeletal markers for the urban population. A statistically significant relationship was found only between IMED and HL. This positive relation was very low (rɸ = 0.307, 0.275) and may be considered non-existent. The lack of co-occurrence is interpreted as if an individual was exposed to conditions that could cause the osteological expression of all three markers this could be a life-threatening health condition, during developing years