The first commercial supercritical water oxidation sludge processing plant

Final disposal of sludge continues to be one of the more pressing problems for the wastewater treatment industry. Present regulations for municipal sludge have favored beneficial use, primarily in land application. However, several agencies and entities have warned of potential health risks associated with these methods. Hydrothermal oxidation provides an alternative method that addresses the health concerns associated with sludge disposal by completely converting all organic matter in the sludge to carbon dioxide, water, and other innocuous materials. A hydrothermal oxidation system using HydroProcessing, L.L.C.'s HydroSolids process has been installed at Harlingen, Texas to process up to 9.8 dry tons per day of sludge. Based on a literature review, this system is the largest hydrothermal oxidation system in the world, and the only one built specifically to process a sludge. Start up of Unit 1 of two units of the HTO system began in April 2001. Early results have indicated COD conversion rates in excess of 99.9%. Harlingen Waterworks System estimates that the HydroSolids system will cost less than other alternatives such as autothermal thermophilic aerobic digestion and more traditional forms of digestion that still require dewatering and final disposal. The Waterworks intends to generate income from the sale of energy in the form of hot water and the use of carbon dioxide from the HydroSolids process for neutralization of high pH industrial effluent. The Waterworks also expects to generate income from the treatment of septage and grease trap wastes.     

A quantitative water resource planning and management model for an industrial park level

This paper introduces an integrated water management model at the industrial park level. It suggests four approaches to water management: first, direct water reuse among users; second, water reuse among users by blending with freshwater; third, water reuse between users and a wastewater treatment plant; and fourth, groundwater recharge by reclaimed wastewater or other feasible applications in order to optimize the overall water efficiency. The model results in a comprehensive management methodology for optimizing water resources within an industrial park, seeking potential water reuse among industries, and incorporating the size and cost of reclaimed wastewater delivery systems. A case study is employed to test the model’s feasibility. An economic analysis of the optimized water use network is also carried out, showing the potential water and cost savings.     

Using biopolymers to remove heavy metals from soil and water

Chemical remediation of soil may involve the use of harsh chemicals that generate waste streams, which may adversely affect the soil's integrity and ability to support vegetation. This article reviews the potential use of benign reagents, such as biopolymers, to extract heavy metals. The biopolymers discussed are chitin and chitosan, modified starch, cellulose, and polymer-containing algae.     

Protecting environmental audits and reports: Balancing self-examination and self-protection

Recently, some companies have begun making environmental reports and internal audits public. Other companies have chosen not to do so. The desire to engage in a critical and thorough self-examination is often thwarted by the fear that audits and other reports may be used against a company in later litigation or administrative proceedings. However, there are some legal, regulatory, and procedural safeguards that can protect a company that chooses to make reports and audits public. This article examines these safeguards, their strengths and weaknesses, and their role in balancing self-examination and self-protection.     

Brevetoxin exposure in bottlenose dolphins (Tursiops truncatus) associated with Karenia brevis blooms in Sarasota Bay, Florida

Bottlenose dolphins (Tursiops truncatus) face a variety of threats, including risk of exposure to brevetoxins produced by blooms of the harmful alga Karenia brevis. This study investigated brevetoxin exposure in a population of dolphins inhabiting Sarasota Bay, Florida, USA (27°N, 82°W), utilizing tissues from dolphins recovered between 1994 and 2003. Brevetoxin levels detected by ELISA in tissues, gastric samples and excreta from dolphin carcasses (n = 19) associated with K. brevis blooms were compared with with levels in carcasses (n = 16) associated with background K. brevis conditions. In the K. brevis-exposed set, 84% of dolphin carcasses recovered during K. brevis blooms had detectable brevetoxin levels, with values ranging between 7 and 2,896 ng PbTx-3 eq g⁻¹. Over 50% of dolphin carcasses recovered during non-bloom conditions also tested positive by ELISA for brevetoxins, with concentrations ranging from 6 to 44 ng PbTx-3 eq g⁻¹. Control samples from the east coast of Florida were negative by the ELISA. Results from this study establish baseline brevetoxin body burdens in a dolphin population frequently exposed to K. brevis blooms, and data indicate that dolphin carcasses not associated with large-scale mortality events can contain levels of brevetoxins comparable to carcasses stranding during such events.     

Dynamics of social nesting in overwintering meadow voles (Microtus pennsylvanicus): possible consequences for population cycling

Summary A small population of meadow voles (Microtus pennsylvanicus) in a field enclosure was studied from August to February in Apalachin, New York, USA. Radiotelemetry provided direct measures of intraspecific spacing and social nesting through the fall-winter transition. Data on weather and predation were collected concurrently. A total of 32 voles were radiotracked during 6 tracking sessions, with an average of 17.3 voles (11 to 25 range) tracked per session (Figs. 1, 2a). Discrete social nesting constellations first occurred during October, primarily as a result of the formation of extended maternal families (Figs. 1, 2e). Recruitment of adult males and offspring into these early nesting groups was male biased. The average number of voles in these groupings varied from 3.2 (Jan; 3–4 range) to 7.0 (Oct; 4–10 range); but the average number of voles that slept together at any given time, the nesting cluster, remained steady at 2.4 (2–5 range) (Fig. 2e). During late December and early January under the protection of snow, many voles shifted their home areas and nesting affiliations with the result that non-lineage nesting constellations formed (Fig. 1, 3). The thermoregulatory benefits of huddling and the threat of predation appear to be important governors of movement, group formation and dispersion. The existence of an optimum group size produces and Allee Effect that may contribute importantly to population lows and multi-annual cycles.     

Economic Development and the Conservation of Large Carnivores

Conserving large carnivores in North America hinges on protecting vast wildlands, a strategy often assumed to carry significant economic costs in terms of jobs and income foregone. Using case studies, we tested whether there is enough evidence to support the assertion that the protection of wildlands is detrimental to economic development in the northern U.S. Rocky Mountains and the Rocky Mountains of southern British Columbia and Alberta. We analyzed employment and income trends in northwestern Montana (U.S.A.) for counties with a high degree of wildland protection versus counties with high levels of resource extraction and little wildland protection. Employment and personal income levels in "wilderness" counties grew faster than in "resource-extraction" counties. Wilderness counties also showed higher degrees of economic diversification and lower unemployment rates. No direct cause-and-effect relationship was established between wildlands protection and economic development, but to the assertion that protecting wildland habitat for large carnivores is detrimental to a region's economy, enough counterevidence is presented to suggest an alternative hypothesis: the protection of wilderness habitat that sustains wild carnivores such as grizzly bears ( Ursus arctos horribilis ) and wolves ( Canis lupus ) does not have a detrimental effect on local or regional economies. Evidence presented suggests that economic growth is stimulated by environmental amenities. Further, case studies in southern British Columbia and Alberta in Canada and the Greater Yellowstone region, in the U.S., where environmental protection has been explicitly recognized as an economic development strategy, suggest that environmental protection and economic development are complementary goals. In some areas, however, "amenity-based" economic growth is rapidly leading to urban sprawl and subsequent loss of wildlife habitat, and there is a need for growth management.