Mad cow and related diseases: Challenges for waste management

Mad cow disease and related transmissible spongiform encephalopathy diseases (TSEs) in both animals and humans have received worldwide attention. Interestingly, the issue of managing biohazardous wastes, for which TSE agents are an issue, has received little attention by environmental professionals. The burial of wastes associated with mad cow and related diseases may eventually lead to unusual challenges for remediation professionals. The core challenge is that medical researchers have confirmed the incredible difficulty in destroying TSE infectious agents or pathogens, generally called prions. Risk reduction is certainly possible with treatment technologies, but complete elimination of risk by reliable and verifiable destruction of all TSE agents is probably infeasible. Proving the efficacy of any waste treatment method for TSE-infected wastes is not practical because there is no commercially available test for TSE pathogens (although one is expected soon) and in only a few cases is there a reasonable surrogate approach. These circumstances have contributed to some biohazardous waste managers discounting the TSE issue. The goal of this article is to more thoroughly analyze available information and various risks to identify useful implications for alternative waste management technologies. A number of prudent actions can be taken in recognition of the TSE problem, including more careful assessment of treatment technologies, avoiding any reuse or recycling of waste treatment residues, using air pollution control systems to avoid releases of materials possibly containing infectious agents, and using wastewater pretreatment prior to sewer disposal.     

Adsorption and transport of arsenic(V) in experimental subsurface systems

The adsorption and transport of As(V) in a heterogeneous, iron oxide-containing soil was investigated in batch and column laboratory experiments. The As(V) adsorbed rapidly to the soil over the first 48 h, but continued to adsorb slowly over the next several weeks, clearly indicating the potential for rate-limited transport. The equilibrium As(V) adsorption isotherm was markedly nonlinear, further indicating the potential for nonideal transport. A model developed for the adsorption of As(V) to hydrous ferric oxide (HFO) was able to predict the pH-dependent adsorption of As(V) to the soil in batch experiments within 0.116 to 0.726 root mean square error (RMSE). Arsenic(V) was significantly retarded in column transport experiments. The column transport experiments were modeled using the one-dimensional advection-dispersion equation, considering both linear and nonlinear adsorption equilibrium. Although the nonlinear local equilibrium model (NLLE, RMSE = 0.273) predicted the data better than the linear local equilibrium model (LLE, RMSE = 0.317), As(V) breakthrough occurred more rapidly than predicted by either model due to adsorption nonequilibrium. However, due to the presence of an irreversible or slowly desorbing fraction, the peak aqueous As(V) concentration (0.624 mg L(-1)) and the total amount of As(V) recovered (44%) was lower than predicted based on the two equilibrium models (NLLE and LLE). For the conditions used in this study [1 mg L(-1) As(V), pH 4.5 and 9,0-0.25 mM PO4, 0.53-1.6 cm min(-1) pore water velocity], the effect on As(V) mobility and recovery increased in the order pH < pore water velocity < PO4.     

The Triad approach: A catalyst for maturing remediation practice

Many individual scientific and technical disciplines contribute to the multidisciplinary field of remediation science and practice. Because of the relative youth of this enterprise, disciplinary interests sometimes compete and conflict with the primary goal of achieving protective, cost‐effective, efficient projects. Convergence of viewpoints toward a more mature, common vision is needed. In addition, cleanup programs are changing under the influence of Brownfields initiatives and the needs of environmental insurance underwriters. Investigations and cleanups increasingly need to be affordable, yet transparent and defensible. Disciplinary goals and terminology need to better reflect real‐world site conditions while being more supportive of project needs. Yet, technical considerations alone will not ensure project success; better integration of human factors into project management is also required. The Triad approach is well placed to catalyze maturation of the remediation field because it emphasizes (1) a central theme of managing decision uncertainty; (2) unambiguous technical communications; (3) shortened project life‐cycles and multidisciplinary interactions that rapidly build professional expertise and provide feedback to test and perfect programmatic and field practices; and (4) concepts from “softer” sciences (such as economics, cognitive psychology, and decision theory) to capture important human factors. Triad pushes the cleanup industry toward an integrated, practical, second‐generation paradigm that can successfully manage the complexities of today's cleanup projects. © 2004 Wiley Periodicals, Inc.     

The influence of soil macroinvertebrates on primary biodegradation of starch-containing polyethylene films

The primary biodegradability of polyethylene (PE) films containing different percentages of cornstarch (0–50%) and other additives (prooxidant, oxidized polyethylene) was tested using four species of earthworms (Eisenia fetida, Lumbricus terrestris, Aporectodea trapezoides, Aporectodea tuberculata), three species of cockroaches (Periplaneta americana, Blaberus sp.,Blattella germanica), termites (Reticulotermes flavipes), sowbugs (Porcellio laevis), and crickets (Acheta domesticus). These studies were conducted to elucidate the potential role of soil macroinvertebrates in degrading starch/PE biodegradable plastics. The results of the macroinvertebrate bioassays indicate that crickets, cockroaches, and sowbugs consumed starch-containing PE films most readily. In addition, the degree to which the films were attacked and consumed was directly related to the starch content of the film. Films with oxidized polyethylene and those containing prooxidant (vegetable oil and a transition metal catalyst) were also consumed. None of the four species of earthworms tested or the termites showed any activity toward the starch/polyethylene films. These results have important implications for determining the fate of novel plastic formulations which claim to be biodegradable in natural environments. Studies such as these, coupled with studies on microbial degradation, will help provide the type of information needed to assess the environmental fate of biodegradable starch/PE plastics and fill the voids in the scientific database regarding this rapidly developing field.     

TRICKLE IRRIGATION OF WHEAT APPLYING RENOVATED WASTEWATER1

ABSTRACT: A preliminary field experiment was conducted for trickle irrigation of winter wheat raised for grain production under arid conditions. Treated waste water was applied for trickle irrigation via a trickle system. Mean total amount of effluent applied was about 5700 m³/ha. In one of the experimental treatments, which was irrigated once a week, a grain yield of over 10,000 kg/ha was obtained, whereas in the other treatments the yields were about 8,500 kg/ha, which are above the mean yield obtained under sprinkler irrigation.     

Temperature dependence of the infinite dilution activity coefficient and Henry's law constant of polycyclic aromatic hydrocarbons in water

The water solubility of 9,10-dihydroanthracene was experimentally determined between 278.12 and 313.17 K. Determinations were carried out by an experimental procedure developed in our laboratory, which is a modification of the dynamic coupled column liquid chromatographic technique. The uncertainty of the experimental determinations ranged from +/- 0.50% to +/- 3.10%. These data, as well as the water solubility data of other five polycyclic aromatic hydrocarbons (PAHs) previously studied, were used to calculate the temperature dependence of the infinite dilution activity coefficient of 9,10-dihydroanthracene, anthracene, pyrene, 9,10-dihydrophenanthrene, m-terphenyl, and guaiazulene in water. Molar excess enthalpies and entropies at infinite dilution, at 298.15 K, were also derived. The temperature dependence of the infinite dilution activity coefficients was used, together with literature values of the vapor pressures of supercooled liquid PAHs (p(B)(sc)), to estimate their Henry's law constants (HLC). Only HLC for anthracene, pyrene, and 9,10-dihydrophenanthrene were calculated, since no p(B)(sc) data were available in the literature for 9,10-dihydroanthracene, m-terphenyl, and guaiazulene. From the observed temperature dependence of the Henry's law constants the enthalpy and entropy of the phase change from the dissolved phase to the gas phase were also derived for anthracene, pyrene, and 9,10-dihydrophenanthrene.     

Modeling using dynamic variables – An approach for the design of loss prevention programs

Records from The National Safety Council [National Safety Council, 2007. Safety Intervention Evaluation: A Systematic Approach. <http://www.acgih.org/events/ControlBand/Thomas_SafetyIntervention.pdf> (accessed 10.01.07)] have shown that in 2004 alone, on-the-job injuries to workers constituted 35% of total recorded injuries in the United States. This generated an associated cost of about $142.2 billion. Unfortunately, the safety intervention programs enforced at work places to mitigate such losses are driven mainly by intuition and experience of involved safety personnel. This paper details implementing a computer program to furnish safety personnel with an empirical basis for designing loss prevention programs based on historical safety data. The computer tool is driven by a dynamic mathematical model which adapts itself to variations in data patterns and explains the correlation between historical incident rates and corresponding resources committed to interventions. This study empowers the industry with a tool that is capable of forming the core of optimizing valuable human resource allocation in safety program designs.     

Targeting Ecosystem Features for Conservation: Standing Crops in the Florida Everglades

Abstract: The Everglades in southern Florida, U.S.A., is a major focus of conservation activities. The freshwater wetlands of the Everglades do not have high species richness, and no species of threatened aquatic animals or plants live there. We have, however, identified a distinctive ecological feature of the Everglades that is threatened by canal construction, draining, and nutrient enrichment from agricultural runoff. Compared to values reported from other freshwater systems, standing stocks of periphyton in relatively undisturbed areas of the Everglades were unusually high, and standing stocks of invertebrates and fish were unusually low. Averaging data gathered from nine sites and five sampling periods spanning 1 year, we found that periphyton standing crop was 88.2 g/m² (ash-free dry mass), invertebrate standing stock was 0.64 g/m² (dry mass), and fish standing stock was 1.2 g/m² (dry mass of large and small species combined). We found that fish standing stocks were much higher in phosphorus-enriched sites than in nearby reference sites but that invertebrate standing stocks were similar in enriched and reference sites. Our results support the notion that oligotrophy is at least partially responsible for the low standing stocks of fish, but they also suggest that species interactions and a paucity of deep-water refugia are important. Anthropogenic eutrophication in Everglades marshes will lead to the loss of distinctive ecosystem features. A focus on species richness and "hot spots" of threatened species provides no basis for conservation of ecosystems like the Everglades. If oligotrophic ecosystems often have low species richness, they will be underrepresented in preservation networks based on some common criteria for establishing conservation priorities.     

Identifying the European Fossil Fuel Plumes in the Atmosphere Over the Northeast Atlantic Region Through Isotopic Observations and Numerical Modelling

As part of the Danish NEAREX project the origin and variability of anthropogenic atmospheric CO₂ over the Northeast Atlantic Region (NEAR) has been studied. The project consisted of a combination of experimental and modelling activities. Local volunteers operated CO₂ sampling stations, built at University of Copenhagen, for ¹⁴C analysis at four locations (East Denmark, Shetland Isles, Faroe Isles and Iceland). The samples were only collected during winter periods of south-easterly winds in an attempt to trace air enriched in fossil-fuel derived CO₂ due to combustion of fossil fuels within European countries. In order to study the transport and concentration fields over the region in detail, a three-dimensional Eulerian hemispheric air pollution model has been extended to include the main anthropogenic sources for atmospheric CO₂. During the project period (1998–2001) only a few episodes of transport from Central Europe towards NEAR arose, which makes the data set for the evaluation of the method sparse. The analysed samples indicate that the signal for fossil CO₂, as expected, is largest (up to 3.7±0.4% fossil CO₂) at the Danish location closest to the European emissions areas and much weaker (up to ∼1.5±0.6% fossil CO₂) at the most remote location. As the anthropogenic signal is weak in the clean atmosphere over NEAR these numbers will, however, be very sensitive to the assumed background ¹⁴CO₂ activity and the precision of the measurements. The model simulations include the interplay between the driving processes from the emission into the boundary layer and the following horizontal/vertical mixing and atmospheric transport and are used to analyse the meteorological conditions leading to the observed events of high fossil CO₂ over NEAR. This information about the history of the air masses is essential if an observed signal is to be utilised for identifying and quantifying sources for fossil CO₂.