Evaluation of Activated Carbon as a Reactive Cap Sorbent for Sequestration of PCBs in Presence of Humic Acid

This study investigated the interferences caused by high humic acid concentrations on the adsorption of coplanar and noncoplanar polychlorinated biphenyls (PCBs) on coconut shell activated carbon. In particular, the research focuses on the application of activated carbon as a reactive cap for contaminated sediment sites, a possible intervention to reduce contaminant flux through pore water, and to organisms in aquatic environments. Kinetic and equilibrium studies were conducted using activated carbon as a sorbent for individual PCB congeners including BZ 1, 52, 77, 153, and 169, respectively, in the presence and absence of humic acid. Results showed that preloading of activated carbon with humic acid significantly reduced the adsorption affinity for all selected PCB congeners. Experiments conducted without preloading of activated carbon demonstrated that desorption upon subsequent spiking with humic acid (simulating long-term exposure to pore water that contains high humic acid concentrations) was not found to be statistically significant, and varied with coplanarity of PCBs. Results provide important information for the design of reactive caps in sediments where high concentrations of dissolved organic carbon are found, and highlight the importance of considering site conditions when designing effective reactive caps

Effect of Humic Acid on Adsorption of Polychlorinated Biphenyls onto Organoclay

Mitigation of risks stemming from contaminated sediments in freshwater and estuarine environments remains an important challenge to the field of environmental science and engineering. Capping sediments with reactive materials is one approach that has recently been the subject of research and development. This research evaluated the use of organoclay as a sorbent in a reactive cap for in situ remediation of contaminated sediments, and provides an original contribution by presenting the sorption characteristics of individual polychlorinated biphenyls (PCB) congeners in the presence of high concentrations of humic acids typical of sediment porewater environments. Sorption of coplanar and noncoplanar PCBs on three commercially available organoclays was studied in this work. Studies were conducted to evaluate the kinetics of adsorption of PCBs on organoclay and to determine the effect of humic acid on the kinetics of adsorption. Isotherm studies were conducted to determine the adsorption affinity of PCBs for organoclays in the presence and absence of humic acid. Studies showed a 45 to 96% reduction in the sorption affinity for organoclays after preloading with high concentrations of humic acid, depending both on the congener and the composition of organoclay. Desorption of PCBs upon addition of humic acid after PCBs were equilibrated with organoclay was statistically significant, although the magnitude of the effect was much smaller than that observed from preloading of humic acid

Bank filtration: a sustainable water treatment technology for developing countries

As good quality water sources become more scare, water quality standards become more stringent and the cost of water treatment is increasing, there is need for a sustainable and robust water treatment technology. Bank filtration has been used for surface water treatment in Europe and USA for many years. However, this technology has not been utilised fully in developing countries. Bank filtration is a natural process of water treatment which is simple, avoids the use of chemicals and when properly designed and operated produces water of acceptable quality and reduces the cost of water treatment. It utilises the physical, chemical and biological removal processes in the soil and aquifer for purification of surface water during its passage to production wells. Based on the results of two feasibility studies conducted in Malawi and Kenya, this paper elaborates on the potentials and constraints of promoting bank filtration technology for water treatment in developing countries

Evaluation of handpump water supply in selected rural and semi-urban areas of Zambia

Handpumps are widely used for water supply in rural and semi-urban areas of Zambia. This could be an attractive technology to provide safe water supply to additional number of unserved people. However, as the handpumps used in Zambia are imported from outside and financed mainly by donors, the sustainability of this water supply system is questionable. This study reviewed different factors affecting sustainability of handpump water supply in Zambia through a field study conducted in selected rural and semi-urban areas of Zambia. The study revealed that despite the low level of support from government and donors during the O&M phase, most of the handpumps are in relatively good condition. Access to spare parts and financing of O&M costs are the main problems in many rural areas of Zambia. Local manufacture of handpumps, continued support from the government agencies and donors in O&M phase and water quality testing is recommended for long-term sustainability of handpump water supply systems in Zambia

From maid to mother: Transforming facilities, staff training, and caregiver dignity in an institutional facility for young children in Nepal

This article provides a case study of a project to improve the health, safety, and development of children birth to 6 years old in a large orphanage in Nepal. Two interventions were conducted: improvement of physical infrastructure and training, mentoring, and support for caregiving staff. As a result of these interventions, positive outcomes in terms of children\u27s health and development have been observed, including reduction of communicable diseases and increased social interactions with caregivers. As part of the new training initiative, the caregivers began to meet regularly to share their ideas and experiences, and came to realize their vital role in the holistic development of the children in their care. One important change was a greater sense of dignity for the caregivers. The caregivers were formerly called Maids(Aaya), but asked to be called Mothers(Aama). The project also faced challenges, including communication barriers related to organizational structure

Multidisciplinary approaches to address food insecurity and nutrition among youth and their families

Our aim in publishing this issue of JARC on nutrition and food insecurity is to understand the factors associated with nutrition and food insecurity in the U.S. and around the world; to elucidate the potential consequences of food insecurity on physical and mental health; and to raise awareness and identify solutions to address this complex issue. We also aim to encourage collaboration across disciplines in order to frame initiatives that reduce these threats to child health, well-being and success

Nanomechanics of Multiple Units in the Erythrocyte Membrane Skeletal Network

Erythrocytes undergo deformations when they transport O(2) and CO(2) across the membrane, yet the 3D nanomechanics of the skeletal network remains poorly understood. Expanding from our previous single isolated unit, we now simulate networks consisting of 1–10 concentric rings of repeating units in equibiaxial deformation. The networks are organized with (1) a 3D model for a single unit, (2) a wrap-around mode between Sp and actin protofilament in the intra-unit interaction, and (3) a random inter-unit connectivity. These assumptions permit efficient five-degrees-of-freedom (5DOF) simulations when up to 30 pN of radial forces are applied to the boundary spectrin (Sp) and the center and other units are analyzed. As 6 Sp balance their tensions, hexagonal units become irregular. While actin protofilaments remain tangent to the network, their yaw (Φ) angles change drastically with addition of neighboring units or an Sp unfolding. It is anticipated that during deformation, transmembrane complexes associated with the network move laterally through the lipid bilayer and increase the diffusion of molecules across the membrane. When protofilament/Sp sweeps under the lipid bilayer, they mix up the submembrane concentration gradient. Thus, the nanomechanics of actin protofilaments and Sp may enhance the transport of molecules during erythrocyte deformation. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10439-010-0040-4) contains supplementary material, which is available to authorized users