The effect of loess addition on the settling ability of activated sludge.

In this research, loess addition was investigated as a possible means of controlling the bulking sludge generated from a sequencing batch reactor (SBR) system treating a synthetic wastewater. The specific objective was to investigate whether loess changed the morphology of the sludge (i.e., influenced the relative abundance of filamentous species), as opposed to improving settling simply because the clay portion of the loess acted as a flocculating agent. To this end, two sets of batch tests were performed using 1 L reactors filled with bulking sludge from the SBR. The first set of batch tests investigated the effect of different loess concentration on the settling properties of the sludge; thus loess was added in concentrations of 0.0, 0.4, 2.0 and 5.0 g L(-1). The 5.0 g L(-1) loess concentration exhibited the most positive results on settling, bringing the modified sludge volume index (SVI) down into the target range of 150 mL g(-1). The second set of batch tests investigated filament length along with the modified SVI. It appeared that at the microbial level, 5.0 g L(-1)of loess caused no reduction in filament length, suggesting no reduction in the amount of filamentous microorganisms. This means that adding loess to a system after it has bulked has the potential to mask the bulking problem by improving settling, while not fixing the problem microbiologically.

Feeding better food habits in mid-20th-century America.

Public health nursing work has always involved education about nutrition and food habits. Nurses serve as interpreters of scientific and medical knowledge and as agents of behavioral change among the individuals and groups for whom they provide care. For public health nurses in mid-20th-century America, this meant direct involvement in many aspects of family life at home. Meal preparation and the eating patterns of family members were two areas into which most public health nurses had access. This brief history provides an introduction to some of the issues confronting American public health nurses at mid-century. Examining the content of articles related to nutrition in families around mid-century yields evidence about the role of the nurse, the state of the art in nutritional knowledge, and opinions and prejudices related to eating habits prevalent at the time. These glimpses into concerns expressed in the original Public Health Nursing journal may enhance understanding of the role of public health nurses in preventing diet-related disorders and form the basis for additional historical research.