Advancing the weight of evidence approach to enable chemical environmental risk assessment for decision-making and achieving protection goals.

The weight of evidence (WoE) approach conflates the aspects of quality, reliability, relevance, and consistency of data and information to systematically strengthen the body of evidence and enable credible communication and decision-making on chemical risk assessment. Between 2015 and 2019, the Society of Environmental Toxicology and Chemistry (SETAC) held several workshops in all the geographical units with scientists and managers from academia, government, and business sectors focusing on the chemical risk-assessment approach. This article summarizes the knowledge that informs the needs concerning application of WoE, especially in the context of developing countries. This effort supports the use of existing data and test strategies for assessing chemical toxicity, exposure, and risk, and highlights the critical process for risk assessors to convey and discuss information sufficiency and uncertainty mitigation strategy with risk managers. This article complements the four articles in the special series that provide a critical review of existing frameworks for chemical risk screening and management, and applications of the WoE approach for assessing exposure in the aquatic environment, prediction of fish toxicity, and bioaccumulation. Collectively, the articles exemplify the use of WoE approaches to evaluate chemicals that are data rich and/or data poor for decision-making. They integrate the WoE concepts and approaches into practical considerations and guidance, and help to scale the value of WoE in supporting sound chemical risk assessment and science-based policy implementation. Integr Environ Assess Manag 2023;19:1188-1191. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Toward Sustainable Environmental Quality: Priority Research Questions for Asia.

Environmental and human health challenges are pronounced in Asia, an exceptionally diverse and complex region where influences of global megatrends are extensive and numerous stresses to environmental quality exist. Identifying priorities necessary to engage grand challenges can be facilitated through horizon scanning exercises, and to this end we identified and examined 23 priority research questions needed to advance toward more sustainable environmental quality in Asia, as part of the Global Horizon Scanning Project. Advances in environmental toxicology, environmental chemistry, biological monitoring, and risk-assessment methodologies are necessary to address the adverse impacts of environmental stressors on ecosystem services and biodiversity, with Asia being home to numerous biodiversity hotspots. Intersections of the food-energy-water nexus are profound in Asia; innovative and aggressive technologies are necessary to provide clean water, ensure food safety, and stimulate energy efficiency, while improving ecological integrity and addressing legacy and emerging threats to public health and the environment, particularly with increased aquaculture production. Asia is the largest chemical-producing continent globally. Accordingly, sustainable and green chemistry and engineering present decided opportunities to stimulate innovation and realize a number of the United Nations Sustainable Development Goals. Engaging the priority research questions identified herein will require transdisciplinary coordination through existing and nontraditional partnerships within and among countries and sectors. Answering these questions will not be easy but is necessary to achieve more sustainable environmental quality in Asia. Environ Toxicol Chem 2020;39:1485-1505. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Modeling nonsteady-state conditions and kinetics of mass transport for hydrophobic compounds in activated-sludge treatment.

A new model that describes the fate of hydrophobic and volatile organic compounds in activated-sludge treatment includes two novel features. First, all of the mass balances are nonsteady state, which allows the model to describe the effects of transients in loading, temperature, or operation. Second, the model describes the mass transfer of hydrophobic compounds with kinetics, not equilibrium. A series of examples demonstrate the new features of the model and how they can be important. When the kinetics of mass transfer are not fast, hydrophobic compounds remain significantly out of equilibrium, even when the system is operating at steady state. When the loading of a hydrophobic compound increases, its aqueous-phase concentration approaches (but does not quite reach) its steady-state concentration much more rapidly than does the density of the adsorbed hydrophobic compound. Finally, the importance of mass-transport kinetics between the aqueous and sorbed phases suggests that research should be focused on this poorly understood mechanism in activated sludge.

Effects of pH and precipitation on autohydrogenotrophic denitrification using the hollow-fiber membrane-biofilm reactor.

Experiments carried out in a hollow-fiber, membrane-biofilm reactor (HFMBR) showed that the optimum pH for autotrophic denitrification was in the range 7.7-8.6, with the maximum efficiency at 8.4. Increasing the pH above 8.6 caused a significant decrease in nitrate removal rate and a dramatic increase in nitrite accumulation. The pH rose by 1.2 units when a large buffer was not added, suggesting that some field applications may require pH control. Precipitation of Ca(2+) occurred in every experiment. Precipitation was the largest sink for carbonate, and it also offset alkalinity production by denitrification. Although the alkalinity increased in most cases, systems with a high carbonate buffer and high pH accentuated precipitation, and the net change in alkalinity was negative. The long-term success of field applications of the HFMBR may depend upon the interactions among calcium concentration, total carbonate concentration, pH, and alkalinity changes.

Applying a novel autohydrogenotrophic hollow-fiber membrane biofilm reactor for denitrification of drinking water.

We conducted a series of pseudo-steady-state experiments on a novel hollow-fiber membrane biofilm reactor used for denitrification of oligotrophic waters, such as drinking water. We applied a range of nitrate loadings and hydrogen pressures to establish under what conditions the system could attain three goodness-of-performance criteria: partial nitrate removal, minimization of hydrogen wasting, and low nitrite accumulation. The hollow-fiber membrane biofilm reactor could meet drinking-water standards for nitrate and nitrite while minimizing the amount of hydrogen wasted in the effluent when it was operated under hydrogen-limited conditions. For example, the system could achieve partial nitrate removals between 39% and 92%, effluent nitrate between 0.4 and 9.1 mg N/l, effluent nitrite less than 1 mg N/l, and effluent hydrogen below 0.1 mg H2/l. High fluxes of nitrate and hydrogen made it possible to have a short liquid retention time (42 min), compared with 1-13 h in other studies with hydrogen used as the electron donor for denitrification. The fluxes and concentrations for hydrogen, nitrate, and nitrite obtained in this study can be used as practical guidelines for system design.