Phytovolatilization of Organic Contaminants

Plants can interact with a variety of organic compounds, and thereby affect the fate and transport of many environmental contaminants. Volatile organic compounds may be volatilized from stems or leaves (direct phytovolatilization) or from soil due to plant root activities (indirect phytovolatilization). Fluxes of contaminants volatilizing from plants are important across scales ranging from local contaminant spills to global fluxes of methane emanating from ecosystems biochemically reducing organic carbon. In this article past studies are reviewed to clearly differentiate between direct- and indirect-phytovolatilization and we discuss the plant physiology driving phytovolatilization in different ecosystems. Current measurement techniques are also described, including common difficulties in experimental design. We also discuss reports of phytovolatilization in the literature, finding that compounds with low octanol-air partitioning coefficients are more likely to be phytovolatilized (log KOA \u3c 5). Reports of direct phytovolatilization at field sites compare favorably to model predictions. Finally, future research needs are presented that could better quantify phytovolatilization fluxes at field scale

Renewable Energy Revenues, Carbon Credits, and Subsidies in Agricultural Waste Treatment Economic Decisions [abstract]

Only abstract of poster available.Track III: Energy InfrastructureAll environmental waste has societal cost, and mitigation is difficult to transfer into benefits that economically justify action. Current subsidies and carbon credit financing have grown to developed within our society to actually put economic resources that are representative of the benefits, and now advanced waste treatment is viable through new economic possibilities related to methane capture and energy production. An economic model was constructed to evaluate the financial potential of anaerobic digestion for swine waste considering initial investments, the associated costs and new revenue streams of carbon credits, renewable energy credits, electricity sales and current available subsidies. The model was formulated based on case-specific inputs and was applied to three case studies in central Missouri. The model inputs were also evaluated by experienced vendors (who have developed similar projects) for validity. The results revealed that the present prices of carbon credits and electricity are not enough to prove the financial feasibility of applying AD technology in all cases without the availability of subsidies. The endeavor also showed that electricity prices have modest impacts on the corresponding Net Present Value of the projects. On the other hand, the carbon credit market projections affect the NPV to a greater degree. Clearly, carbon credit markets may play a pivotal role in widespread development and implementation of the technology. In all the three scenarios the projects were profitable with the presence of the current state and federal subsidies. However, since the subsidies may not be available for many years, high Carbon Credit and electricity prices are needed for future profitability of the technology

Predictive Relationships for Uptake of Organic Contaminants by Hybrid Poplar Trees

Twelve Organic Compounds Commonly Found at Hazardous Waste Sites Were Studied for Uptake by Hybrid Poplar Trees. the Vegetative Uptake of Many of These Compounds Has Not Previously Been Demonstrated for Plant Species Being Utilized for Phytoremediation, Such as Hybrid Poplar Trees. Experiments Were Conducted Hydroponically Utilizing 14C-Labeled Compounds to Ascertain Translocation and Fate. Predictive Relationships for the Translocation and Partitioning to Plant Tissues Were Developed from the Experimental Data. Translocation and Partitioning Relationships based on Compounds\u27 Octanol- Water Partitioning Coefficients (100 K(Ow)) Produced the Best Results, But the Relationships Did Not Allow for Fully Accurate Prediction of Each Contaminant\u27s Fate. Translocation and Subsequent Transpiration of Volatile Organic Compounds (VOCs) from the Leaves to the Atmosphere Was Shown to Be a Significant Pathway. as Full-Scale Phytoremediation Systems Are Deliberated; the Pathways Investigated Here Should Be Considered in Terms of a Contaminant Removal Mechanism and Potential Contamination of the Vegetation

Uptake and Metabolism of Atrazine by Poplar Trees

Hybrid Poplar Trees Can Uptake, Hydrolyze, and Dealkylate Atrazine to Less Toxic Metabolites. in Whole Plant Studies, the Parent Compound Atrazine and 14C Ring-Labeled Metabolites Were Extracted from Poplar Tissues and Analyzed Via High-Pressure Liquid Chromatography (HPLC) with UV and Radiochromatographic Detectors in Series. the Concurrent Separation and Identification of These Metabolites Has Not Been Previously Reported in Higher Plants for Phytoremediation Applications. Unidentified Metabolites Were Also Detected. Metabolism of Atrazine Occurred in Poplar Roots, Stems, and Leaves and Became More Complete with Increased Residence Time in Tissues. in Poplar Cuttings Exposed to Atrazine for 50 Days, the Parent Compound Comprised Only 21% of the 14C Label in the Leaves, While It Constituted 59% of 14C Activity Remaining in the Soil. after 80 Days, the Parent Compound Remaining in the Leaves Had Decreased to Only 10% of the 14C Label Recovered in the Leaves. Preferred Metabolic Pathways Were Suggested by Relative Rates of Reaction, and a Mathematical Model Was Developed to Estimate Rate Constants for the Proposed Degradation Mechanism. This Research Provides Evidence for Vegetative Detoxification of Contaminants and Suggests that Phytoremediation of Atrazine-Contaminated Soils May Be Feasible

Natural Treatment and On-Site Processes

The Natural Treatment Systems, Which is Divided into Land-Treatment, Wetland, Aquatic, Onsite and Small Community, and Phytoremediation Systems, Are Discussed. This Include the Free Water Surface Constructed Wetlands, Subsurface Flow Constructed Wetlands, Vertical Flow Constructed Wetlands,ponds, Floating Aquatic Plant Systems, Solar Aquatic Systems, Small Treatment Systems, and In-Ground Disposals

Effect of Seeding Materials and Mixing Strength on Struvite Precipitation

Struvite Precipitation Has Increasing Interest as a Technology for Removing and Recovering Phosphorus from Wastewater Streams. Many Chemical Factors Have Been Studied, Such as Optimum PH Values and Component-Ion Molar Ratios, Yet, Understanding of Physical Aspects is Lacking. Two Physical Parameters Were Tested: (1) Seeding Material Addition and (2) Mixing. Objectives Were to Evaluate Three Seeding Materials and to Optimize Mixing Conditions for Struvite-Crystal Precipitation, Growth, and Subsequent Sedimentation. Results Confirm that Mixing Strength and Proper Seeding Materials Increase Crystal Size and Improve Settleability. for Unseeded Solutions, Optimum Phosphorus Removal Was Achieved at a Mixing Strength of G = 76 S-1. Struvite Crystals that Were Added as the Seeding Material Provided the Best Performance with Respect to Phosphorus Removal and Crystal-Size Distribution. overall, This Study Provided Information to Improve the Practical Application of Struvite Precipitation as a Phosphorous-Treatment Technology for Wastewaters, While Generating a Marketable Slow-Release Fertilizer as a Product