An introduction to decision science for conservation

Biodiversity conservation decisions are difficult, especially when they involve differing values, complex multidimensional objectives, scarce resources, urgency, and considerable uncertainty. Decision science embodies a theory about how to make difficult decisions and an extensive array of frameworks and tools that make that theory practical. We sought to improve conceptual clarity and practical application of decision science to help decision makers apply decision science to conservation problems. We addressed barriers to the uptake of decision science, including a lack of training and awareness of decision science; confusion over common terminology and which tools and frameworks to apply; and the mistaken impression that applying decision science must be time consuming, expensive, and complex. To aid in navigating the extensive and disparate decision science literature, we clarify meaning of common terms: decision science, decision theory, decision analysis, structured decision-making, and decision-support tools. Applying decision science does not have to be complex or time consuming; rather, it begins with knowing how to think through the components of a decision utilizing decision analysis (i.e., define the problem, elicit objectives, develop alternatives, estimate consequences, and perform trade-offs). This is best achieved by applying a rapid-prototyping approach. At each step, decision-support tools can provide additional insight and clarity, whereas decision-support frameworks (e.g., priority threat management and systematic conservation planning) can aid navigation of multiple steps of a decision analysis for particular contexts. We summarize key decision-support frameworks and tools and describe to which step of a decision analysis, and to which contexts, each is most useful to apply. Our introduction to decision science will aid in contextualizing current approaches and new developments, and help decision makers begin to apply decision science to conservation problems.     

Treatment of poly- and perfluoroalkyl substances in groundwater using a carbon-based micro-adsorbent and ceramic membrane filtration

This article presents the results of an Environmental Security Technology Certification Program (ESTCP) demonstration conducted at Horsham Air Guard Station and the former Willow Grove Naval Reserve Station in Horsham, Pennsylvania. The ESTCP project information can be found here: https://www.serdp-estcp.org/projects/details/568c0487-f182-40c1-9d4d-9297f4bbedda/er19-5181-projcet-overview . The technology demonstrated, identified as the AquaPRS™ system, employs a carbon-based micro-adsorbent suspension to adsorb polyfluoroalkylated substance (PFAS), which is subsequently filtered using a ceramic membrane filter. A prototypical AquaPRS system was specifically designed and implemented to treat per- and PFAS-contaminated water resources at a fidelity level that could be replicated at other US Department of Defense sites. The objective of the project was to demonstrate and validate the application of the adsorption and separation treatment approach to reduce the total life-cycle cost of treating PFAS-impacted groundwater. The results of the demonstration showed that the AquaPRS technology provides an alternative to granular activated carbon (GAC) and ion exchange (IX) systems based on treatment efficacy and cost performance using lifecycle cost analyses. Pretreatment included cloth media filtration with a nominal 5 µm particulate rejection rating to remove sediment from the surface water treated during the Horsham evaluation. Prefiltration was not necessary for treating the Willow Grove groundwater due to the lower raw turbidities. The micro-adsorbent was added to the system to maintain a suspension between 1 and 50 g/L in the sorbent chamber at reaction times from 5 to 20 min. Treated effluent was separated from the sorbent slurry matrix using the ceramic membrane filter, with the slurry returned to the sorption reactor. The first study conducted at Horsham Air Guard Station demonstrated and validated the AquaPRS treatment approach using a mobile pilot system, while the second study (conducted at the former Naval Reserve Air Station at Willow Grove) provided further optimization of cost, performance, and scalability. At Horsham, 13 tests were conducted over 9 months using a dual-train pilot with each test evaluating two separate conditions. The first 10 tests were conducted with treatment systems in parallel and the remaining three were conducted in series. At Willow Grove, five tests were conducted over a 6-month period for a total of 10 individual test conditions. Three tests were performed in parallel with two operated in series. Tests conducted at Horsham evaluated the performance of the AquaPRS system at different hydraulic detention times (5–120 min), sorbent mass (10–430 g), sorbent densities (0.5–40 g/L), and flowrates (0.1–1 L/min). At Willow Grove, the range of these parameters was further narrowed with hydraulic detention times from 10 to 20 min, sorbent mass from 100 to 200 g, sorbent density from 10 to 25 g/L, and flowrate from 0.67 to 1 L/min. AquaPRS was validated by quantifying the specific adsorption rate (SAR) of various PFASs on the micro-adsorbent and comparing it to values derived for GAC and IX from the same water matrix. The costs of the three treatment systems were compared to estimate a payback period for the AquaPRS system compared to GAC and IX. At 10% breakthrough, the SAR of AquaPRS for the combined concentration of the United States Environmental Protection Agency's Third Unregulated Contaminant Monitoring Rule (UCMR3) PFASs was nearly 300 times higher compared to those treated with GAC. At 40 ng/L breakthrough for combined UCMR3 compounds, a single-stage AquaPRS system at Horsham achieved 146 µg PFAS/g sorbent SAR, while a dual-stage system at Willow Grove achieved 2128 µg PFAS/g sorbent. The AquaPRS system showed a breakeven period of 8 months compared to a similarly designed GAC system in the Horsham evaluation using the observed adsorption rates. In the Willow Grove test case, a 24–36-month breakeven period was determined for the AquaPRS technology when compared to the highest sorption rates observed among five previously tested IX resins. The AquaPRS benefits in comparison to GAC/IX include effective performance in the presence of co-contaminants, adaptability to changing conditions, limited downtime for sorbent replacement, resistance to biofouling, small footprint, and reduced disposal requirements. The lower waste production rates are due to the AquaPRS' ability to dewater the spent sorbent resulting in a waste generation of just 0.002% of the total volume of water treated. Based on the treatment efficacy and cost performance, the AquaPRS system is positioned as an alternative to GAC and IX systems.     

The Importance of Environmental Factors in Forecasting Australian Power Demand

Environmental Modeling & Assessment - We develop a time series model to forecast weekly peak power demand for three main states of Australia for a yearly timescale, and show the crucial role of...