Precipitation of heavy metals from wastewater using simulated flue gas: sequent additions of fly ash, lime and carbon dioxide

Lime is a preferred precipitant for the removal of heavy metals from industrial wastewater due to its relatively low cost. To reduce heavy metal concentration to an acceptable level for discharge, in this work, fly ash was added as a seed material to enhance lime precipitation and the suspension was exposed to CO2 gas. The fly ash-lime-carbonation treatment increased the particle size of the precipitate and significantly improved sedimentation of sludge and the efficiency of heavy metal removal. The residual concentrations of chromium, copper, lead and zinc in effluents can be reduced to (mg L-1) 0.08, 0.14, 0.03 and 0.45, respectively. Examination of the precipitates by XRD and thermal analysis techniques showed that calcium-heavy metal double hydroxides and carbonates were present. The precipitate agglomerated and hardened naturally, facilitating disposal without the need for additional solidification/stabilization measures prior to landfill. It is suggested that fly ash, lime and CO2, captured directly from flue gas, may have potential as a method for wastewater treatment. This method could allow the ex-situ sequestration of CO2, particularly where flue-gas derived CO2 is available near wastewater treatment facilities. (C) 2009 Elsevier Ltd. All rights reserved.

Coping, conversation tactics and marital interaction in persons with acquired profound hearing loss (APHL): correlates of distress

This study investigated coping strategies, conversation tactics, and marital interaction in acquired profound hearing loss (APHL) and compared emotionally stable (n = 15) and emotionally distressed (n = 7) participants. Nominated family members were assessed on most measures. Comparisons were also made in the subgroup of married participants. A combined distress criterion was derived from scores on standardized measures of anxiety, depression, hearing handicap, and post-traumatic stress. Groups were compared on the Ways-of-Coping Checklist, a newly devised measure of conversation tactics, and on the Couple Behaviour Report. It was found that distressed APHL participants were more likely to cope through avoidance, self-blame, and wishful thinking, and they used more avoidant tactics in conversation. The coping profile of family members did not differentiate distress groups. However, there was some indication of greater employment of coercive tactics by family members of distressed participants. The results are consistent with the view that the coping style of a person with APHL and the nature of their conversational interactions with family members contribute to their level of distress. Implications for audiological rehabilitation are discussed.

Semantic and conceptual structures in module design

This paper describes the employment of semantic and conceptual structures in module design, specifically course modules. Additionally, it suggests other uses of these structures in aiding teaching and learning.