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Earthworms are used as biomarkers to determine the bioavailability of contaminants. As such, their uptake of contaminants has been studied extensively. Protocols have been established to ensure that laboratory-obtained data are valid and comparable. However, the method of removing the organism’s gut content (depuration) before assessing the contaminant in the tissue is not standardized. The aim of this research project is to investigate some parameters for earthworm depuration: light conditions and coprophagy prevention. Eisenia fetida were depurated for 48 hours in two separate studies according to guidelines ASTM-E1676 and OECD Test No. 317. In one study, 2 frequencies of egesta removal were employed during depuration to prevent coprophagy and compared to the control (egesta and worms removed after 48 hours). In another study, the subjects and material egested were assessed under conditions of continuous darkness and the control (continuous light). The depuration methods that included egesta removal every 12 and 24 hours resulted in 62% and 10% more egested material per mg of earthworm than the control (filter paper disc change after 48 hours), respectively. The earthworms depurated in continuous darkness egested 94% more material per mg of earthworm than the control. The results indicate that depuration would be more total under continuous darkness and employing a coprophagy prevention method. These findings could lead to more efficient depuration methods.

The lack of efficient methods to treat As-rich biomass is a drawback for phytoremediation technology. In this study, we applied anaerobic digestion to reduce biomass and remove As from As-rich Pteris vittata biomass. P. vittata biomass including control (3.1 mg kg−1 As) and As-rich (2665 mg kg−1 As), together with positive and negative controls, was anaerobically digested at 35 °C for 35 d. Arsenic partitioning among gas, liquid and solid phases after anaerobic digestion was determined. Methane index potential assay was used to assess methane yields whereas liquid-displacement method was used to measure methane gas production. After 35 d, As partitioning in the liquid, solid and gas phases was 79, 30 and 1%, respectively. Besides, volatile solid was decreased from 91 to 12–17% total solid, while P. vittata biomass was decreased by 73–83%. Moreover, anaerobic digestion solubilized 76% As from P. vittata biomass, with 90% soluble As at 4.95 mg L−1 being recovered by As-Mg precipitation. Finally, methane production after 35 d was 197–212 LNCH4/kg volatile solid, showing slight As inhibition. Effective As removal from P. vittata biomass prior to disposal can improve the phytoremediation process.

Dispersal is a key process that impacts population dynamics and structures biotic communities. Dispersal limitation influences the assembly of plant and microbial communities, including mycorrhizal fungi and their plant hosts. Mycorrhizal fungi play key ecological roles in forests by feeding nutrients to plants in exchange for sugars, so the dispersal of mycorrhizal fungi spores actively shapes plant communities. Although many fungi rely on wind for spore dispersal, long-distance dispersal is uncommon and most spores land close to fungal fruiting bodies. Some fungi have lost the ability to shoot their spores into the air and instead produce enclosed belowground fruiting bodies (truffles) that rely on animals for dispersal. Animal-facilitated spore dispersal increases the chances that spores reach suitable habitats and colonize plant roots. The role of mammals in fungal spore dispersal is well documented but the relevance of birds as dispersal agents of fungal spores has been understudied, despite the prominence of birds as seed dispersal vectors. Here we use metagenomics and epifluorescence microscopy to demonstrate that two common, widespread and endemic birds from Patagonia, Chucao Tapaculos (Scelorchilus rubecula) and Black-throated Huet-huets (Pteroptochos tarnii), regularly consume mycorrhizal fungi and disperse viable spores via mycophagy. We sampled more than 100 fecal samples that were collected across a 700 kilometer area in Patagonia. Our metagenomic analysis indicates that these two species of generalist, ground-dwelling birds routinely consume diverse mycorrhizal fungi, including many truffles, that are symbiotically associated with Nothofagaceae trees that dominate Patagonian forests. We used soil sample controls to ensure that fecal samples were not contaminated from nearby soil as well as extraction, PCR and sequencing controls to account for lab contamination. Epifluorescence microscopy of fecal samples confirmed that the birds dispersed large numbers of viable spores from truffles and other mycorrhizal fungi, including Cystangium nothofagi and species of Cortinarius, Descolea, and Inocybe, which are important root colonizers of seedling and saplings of several Nothofagaceae species. Our results show that fungi are a common food for both bird species and that this cryptic animal-fungi symbiosis is widespread and ecologically important in Patagonia. Our findings suggest that birds may also act as cryptic but critical agents of fungal spore dispersal in other ecosystems.

Algae cultivation has multiple potential applications including biofuel production, wastewater treatment, and carbon capture. However, dewatering and dehydration remain a challenge for commercialization. Research has focused mainly on microalgae, but filamentous algae have recently gained attention due to their larger size and thus relative ease of harvesting. The drying mechanics of filamentous algae has yet to be fully understood and optimized. This study investigated the drying behavior of the filamentous algae Oedogonium at 50℃, 60℃ and 70℃. The moisture content of triplicate samples of microalgae and Oedogonium (intact filaments, fractured filaments, and aggregated forms) was measured during drying. Intact Oedogonium filaments were fractured using a food blender. Intact Oedogonium had an average shorter falling rate phase and higher diffusivity then microalgae at all temperatures, resulting in a 15%, 8.3%, and 11% faster total average drying time at 50℃, 60℃ and 70℃ respectively. Fractured Oedogonium further had a shorter falling rate phase than intact Oedogonium at 50℃ and 60℃ where its average total drying time was respectively 18% and 9% faster, but the effect of the fracturing treatment reduced with increasing temperature and became negligible at 70℃. Thus, Oedogonium appears to dry more effectively than microalgae, and fracturing Oedogonium results in faster dehydration at lower temperatures. These findings could help optimize industrial drying and assist in the commercialization of algae cultivation.

A system dynamics modeling approach was used to assess the potential impact of intentional struvite crystallization recovery on wastewater treatment plant (WWTP) allocation of N and P in effluent and biosolids outputs. Struvite crystallization has been used to recover wastewater N and P and produce valuable fertilizer. However, it is often overlooked whether additional benefits may be realized by diverting N and P from other fates. A system dynamics model was used with operational data from three activated-sludge WWTPs in North Florida. Incorporating struvite crystallization reduced the effluent P load by 37 to 100%, dependent upon the WWTP. This may translate into substantial savings for systems facing severe restrictions in effluent P release outside the plant. Additionally, biosolids P load reductions ranged from 17 to 46%. The model also predicted a 37% average increase in the biosolids N:P ratio. Increasing the N:P ratio may allow for greater biosolids land-application rates where P fertilizer restrictions exist. In comparison, the N load reductions were much less dramatic, i.e. below 10% reduction from the effluent and 14% from the biosolids. Most N inputs into an activated-sludge type WWTP are likely lost through denitrification during wastewater processing and struvite does not appear to be a significant means of recovering N from small WWTPs. However, incorporating struvite recovery into even the simplest WWTPs reduces effluent post-treatment needs and results in a more useful biosolids product.

Animal waste has been studied as a potential fuel source via anaerobic digestion. Feces have also been used to inoculate biodigesters. Biodigesters are a waste treatment solution that use anaerobic digestion to convert organic matter into methane. They utilize microbes to break down organic matter into substrates which are then converted into methane as fuel. The final step’s productivity depends on the methanogen content of the biodigester. This study evaluated the feces of captive animals for use as a methanogenic inoculum. The aim was to assess the potential of different feces for methanogen contribution through a literature review and sample analysis via fluorescence microscopy to observe F420 autofluorescence. Coenzyme F420 is a fluorescent coenzyme involved in redox reactions in methanogens and is used in their identification and observation. The samples were from herbivores in the orders Rodentia (rodents), Lagomorpha (rabbits), Perissodactyla (odd-toed ungulates), Artiodactyla (even-toed ungulates), and Diprotodontia (some marsupials). The literature review favored goats and sheep over the other animals in the study. The feces from each animal species tested were observed to have some methanogen presence, but the levels were low and differences were not discernible. Overall, the results of the sample analyses were inconclusive due to the scarcity of methanogens and obscuration due to foliage fragments. Keywords: Fecal, Methanogens, Coenzyme F420, Anaerobic digestion, Biodigester, Inoculum

Dispersal is a key process that impacts population dynamics and structures biotic communities. Dispersal limitation influences the assembly of plant and microbial communities, including mycorrhizal fungi and their plant hosts. Mycorrhizal fungi play key ecological roles in forests by feeding nutrients to plants in exchange for sugars, so the dispersal of mycorrhizal fungi spores actively shapes plant communities. Although many fungi rely on wind for spore dispersal, some fungi have lost the ability to shoot their spores into the air and instead produce enclosed belowground fruiting bodies (truffles) that rely on animals for dispersal. The role of mammals in fungal spore dispersal is well documented, but the relevance of birds as dispersal agents of fungi has been understudied, despite the prominence of birds as seed dispersal vectors. Here, we use metagenomics and epifluorescence microscopy to demonstrate that two common, widespread, and endemic Patagonian birds, chucao tapaculos (Scelorchilus rubecula) and black-throated huet-huets (Pteroptochos tarnii), regularly consume mycorrhizal fungi and disperse viable spores via mycophagy. Our metagenomic analysis indicates that these birds routinely consume diverse mycorrhizal fungi, including many truffles, that are symbiotically associated with Nothofagaceae trees that dominate Patagonian forests. Epifluorescence microscopy of fecal samples confirmed that the birds dispersed copious viable spores from truffles and other mycorrhizal fungi. We show that fungi are a common food for both bird species and that this animal-fungi symbiosis is widespread and ecologically important in Patagonia. Our findings indicate that birds may also act as cryptic but critical fungal dispersal agents in other ecosystems.

An industrial sweetpotato cultivar, CX-1, offers several advantages as an alternative crop for bioethanol production, including high agronomic productivity and high starch content as well as viable coproducts for additional bioenergy recovery. A two-year agronomic field trial resulted in a root yield of 12.3 dry t ha−1 after optimization of planting strategy and improved site drainage. Starch content (73.5% dry matter (DM) for Year 1 and 72.1% DM for Year 2) exceeded that of any other industrial variety grown in the Southeastern USA. In contrast to other industrial cultivars, starch concentrations were maintained over a six-month storage period, making this a favorable year-round feedstock. The bioethanol potential of the CX-1 (4.2 t ha−1 or 5300 L ha−1) was determined based on the conversion of CX-1 dry biomass into ethanol by simultaneous saccharification and fermentation combined with the agronomic root yield from the Year 2 field trial. The cull rate was 36% of the overall root yield, as determined based on United States Department of Agriculture culinary grades. However, assessment of the culls from an industrial processing perspective would significantly reduce the cull rate. Approximately 45% of the culls were classified as cull material (i.e. secondary rootlets) that could feasibly be converted into ethanol. The remaining 55% of the culls could be used for biogas recovery to offset the energy required to produce ethanol from sweetpotatoes.

Small, municipal wastewater treatment plants (WWTPs) that use aerobic digestion treat approximately 40% of the discharged wastewater in the USA, and yet they are an overlooked source of recoverable P. There are no known reports of small, aerobic WWTPs recovering P through struvite (MgNH4PO4&middot, 6H2O) precipitation for repurposing as a mineral fertilizer, even though some large WWTPs with anaerobic digestion are. Four small WWTPs in north Florida, USA, with treatment capacities from 371 to 2650 m3 wastewater d&minus, 1 and incoming P loads from 2 to 14 kg d&minus, 1 were investigated for their potential to produce struvite from digester filtrates. A chemical equilibrium model was used to predict the feasibility of struvite production and the results compared with actual WWTP filtrate measurements. Filtrates from aerobic digesters were able to form struvite if solution pH was increased by &le, 1 pH unit. Depending on the WWTP, P recovery in filtrates through struvite precipitation ranged from 27&ndash, 57% by mass at pH 8.5, via NaOH additions or air sparging. Increasing filtrate Mg concentrations improved P recovery up to 97%. Based upon these results, small WWTPs using aerobic digestion will be able to lower their P waste output through recovery as struvite fertilizer.

As the planet is faced with depletion of its natural resources, alternative and sustainable energy sources are becoming increasingly sought after. Research on the growth of algae has revealed their potential for carbon capture to reduce greenhouse gas emissions and for conversion into a fuel source for bioenergy applications. Filamentous algae have attracted recent attention as an optimal species due to their ease of harvest and dominance over other species. To determine the most suitable species for future biomass applications, a 1000-L open raceway pond was inoculated with the freshwater filamentous alga, Oedogonium. The pond culture was harvested weekly to determine the effects of CO2 addition on culture density (mg VSS/L) and harvest productivity (g VSS/m2-day). An additional two 1000-L raceway ponds with established cultures of microalgae already receiving CO2 were used as a comparison to the growth of Oedogonium. After 3 weeks, Oedogonium harvest productivity exceeded both microalgal ponds at 13.7 (± 0.2) g VSS/m2-day compared to 9.3 (± 0.7) and 9.5 (± 0.3) g VSS/m2-day for the microalgae.

The first- and second-generation bioethanol by-products (bagasse and fermentation by-product, respectively) have different biochemical characteristics relating to carbon (C) and nitrogen (N) due to their production processes. To examine the impacts of fermentation by-product and bagasse on soil C and N dynamics, a 120 day laboratory incubation experiment was conducted by applying these amendments in soil at an equal carbon application rate (2.2 g C kg−1 soil). There was a significant increase in overall cumulative CO2-C production from amended soil compared to the control soil, though the loss was greatest in bagasse amended soil. However, δ13C-CO2 measurements suggested that fermentation by-product addition suppressed native soil C mineralization and prompted strong negative C priming (−57%). In contrast, bagasse amendment maintained similar native soil C mineralization to control soil. Decreased microbial biomass turnover time appears to be the major driving force for increased CO2-C production and soil C loss following bioethanol by-product amendments. Increased mineral N production indicated net N mineralization after fermentation by-product addition, while addition of bagasse resulted in lower N availability and N immobilization. Overall, results suggested that fermentation by-product application is advantageous in maintaining native soil C stock and N mineralization compared to bagasse. Thus, in a sustainable second-generation bioethanol production system, bagasse may be used for second-generation bioethanol production and the cogenerated by-product could be used as an amendment to improve soil C stock and N availability.

Background: Sustainable agricultural systems must support nutritional requirements, meet the energy demands of a growing population, preserve environmental resources and mitigate climate change. The sweetpotato (Ipomoea batatas L.) is a high-yielding crop that requires minimal fertilization and irrigation, and the CX-1 industrial cultivar offers superior potential for feed and fuel.; Results: CX-1 had the highest agronomic fresh vine yield (51.5 t ha-1 ), averaged over two cropping seasons, compared with Hernandez (33.7) and Beauregard (21.8) varieties. CX-1 vines were more nutritional than the table varieties, specifically in regard to relative feed value (205), water-soluble carbohydrates (171 g kg-1 dry matter (DM)), total digestible nutrients (643 g kg-1 DM), metabolizable energy (10.2 MJ kg-1 DM) and organic matter digestibility. Their lower fiber and lignin concentrations contributed to their freshness and digestibility throughout maturity. Significantly higher iron concentrations make the CX-1 vines a valuable, low-fat iron supplement for animal feed. The CX-1 roots also showed the highest bioethanol potential (82.3 g ethanol kg-1 fresh root) compared to Hernandez (64.5) and Beauregard (48.1).; Conclusion: The CX-1 industrial sweetpotato is an ideal dual-purpose crop for tropical/subtropical climates that can be utilized as a non-grain-based feedstock for bioethanol production while contributing a valuable, high-yielding nutritional supplement for animal feed. © 2016 Society of Chemical Industry.; © 2016 Society of Chemical Industry.

Summary The great need for more sustainable alternatives to fossil fuels has increased our research interests in algal biofuels. Microalgal cells, characterized by high photosynthetic efficiency and rapid cell division, are an excellent source of neutral lipids as potential fuel stocks. Various stress factors, especially nutrient‐starvation conditions, induce an increased formation of lipid bodies filled with triacylglycerol in these cells. Here we review our knowledge base on glycerolipid synthesis in the green algae with an emphasis on recent studies on carbon flux, redistribution of lipids under nutrient‐limiting conditions and its regulation. We discuss the contributions and limitations of classical and novel approaches used to elucidate the algal triacylglycerol biosynthetic pathway and its regulatory network in green algae. Also discussed are gaps in knowledge and suggestions for much needed research both on the biology of triacylglycerol accumulation and possible avenues to engineer improved algal strains.

Nutrient concentration and availability vary substantially among composts depending on the materials used and the production process. Composts produced from agricultural operations typically utilize animal wastes such as manures, whereas composts produced in urban areas mainly incorporate food and yard waste. Our objective was to assess how different composts affect nutrient availability and cycling, mostly carbon (C) and nitrogen (N). In a laboratory incubation, we compared three composts derived from cow manure (composted dairy manure solids, vermicompost made from those manure solids, and Black KowTM) and two composts derived from food waste (composted food waste from the UF-IFAS Compost Cooperative and EcoscrapsTM). We used two sandy soils from Gainesville, FL: one from an area under perennial grasses and a second heavily-tilled soil lower in organic matter. Incubations were conducted for eight weeks at 24 and 30 &deg, C, i.e., the annual and July mean soil temperature for the area. The composted and vermicomposted cow manure solids had the greatest CO2 emissions relative to the unamended soils. Soil nitrate was highest with composted food waste, whereas all three cow manure-derived composts resulted in lower soil nitrate compared to the unamended soils. This suggests that N was immobilized with cow manure-derived composts, consistent with the high CO2 emissions measured with these amendments. We found similar results for both soils. Our results indicate a greater potential for food-waste compost as a nutrient source than compost derived primarily from cow manure solids, which could be more beneficial to building soil C.

Improper disposal of arsenic-rich biomass and the lack of efficient methods to treat it may cause contamination in the environment. We developed an efficient method for arsenic (As) removal and biomass reduction of As-rich biomass of the As-hyperaccumulator Pteris vittata by coupling ethanol extraction with anaerobic digestion. This study assessed As partitioning among the three phases (gas, liquid and solid) after anaerobic digestion of P. vittata biomass. Biomass with and without As was first extracted with ethanol. Ethanol extraction removed ~93% As, with remaining As concentration at 197 mg kg−1. The extracted biomass was then digested at 35 °C under anaerobic conditions for 35 d. Arsenic in the digested biomass was reduced by 89%, with remaining As concentration at 60 mg kg−1. In addition, anaerobic digestion reduced the biomass by 64–71% and decreased the volatile solids content from 94 to 15–18%. Methane production was 145 and 160 LNCH4/kgVS after 35 d for As-rich and control biomass, respectively. As a final step, As concentration in anaerobic digestate supernatant was reduced to 0.26 mg L−1 by As-Mg precipitation. Overall, coupling ethanol extraction with anaerobic digestion decreased As concentration in P. vittata biomass from 2665 to 60 mg kg−1, or by 98%. At this level (

Concerns about the negative impacts of crop biomass removal on soil ecological functions have led to questioning the long-term sustainability of bioenergy production. To offset this potential negative impact, use of organic C rich by-products from the bioenergy industries have been proposed as a means to replenish soil C in degraded soils. However, the impact of these by-products application on soil carbon dynamics is not fully understood. We measured biogeochemical changes in soil organic C following a three-year field application of two by-products, biochar (BC) and fermentation-by product (FBP), of bioenergy industry processes in an elephant grass [Pennisetum purpureum (L.) Schum.] field. There was a significant increase in overall soil organic C (SOC) observed in BC (270%) treated plots, however the higher labile SOC (51%) content was present in FBP treated plots. Solid-state 13C NMR spectroscopy further revealed increased aromatic and alkyl groups in BC amended soils which lend to its significantly higher hydrophobicity index, HI (2.13) compared with FBP amended soils (HI = 0.8). Initial biogeochemical responses of amended soils to drought conditions were also investigated during a short-term experiment with drying and rewetting of soils. Increased concentrations of extractable C and higher stimulation of microbial activities (respiration and enzyme activities) in FBP amended soils were measured. Overall, our results reveal different impacts of the two soil amendments, where FBP soil application can affect the labile SOC availability, and stimulate rapid microbial response in drought affected soils, and biochar soil application lowers the labile SOC and microbial stimulation facilitating C sequestration over time.

The ability of As-hyperaccumulator Pteris vittata to remove As from two contaminated soils (CCA from an As-treated wood facility and DVA from a cattle-dipping vat) over 5 years was investigated for the first time. The goal was to evaluate P. vittata's ability to continuously remove As during 10 harvests and identify how soil As was affected by P. vittata under P-sufficient (P-fertilizer) and P-limiting (phosphate rock) conditions. Sequential extraction was used to determine changes in metal distribution among different soil fractions. The high frond biomass production occurred on the 9th (62.1–63.9 and 35.6–63.5 g plant−1) and 10th harvest (58.6–60.7 and 51.9–57.1 g plant−1) for CCA and DVB soils, though frond As concentration decreased. Soil arsenic removal averaged 7–10% per harvest during the 1–6th harvests and was reduced to 0–3% during the 7–10th harvests for DVA and CCA soils. Arsenic from all fractions, excluding the residual fraction, was affected by plant uptake. The largest reduction occurred in the amorphous fraction of CCA-soil at 64–66% (61.2–61.5 to 20.8–21.8 mg kg−1) and in the crystalline fraction of DVA-soil at 50–86% (2.18–4.35 to 0.61–1.10 mg kg−1). Soil As concentrations were reduced by 37–47% from 26.7 to 129 to 15.6–16.8 and 68.9–70.1 mg kg−1 for the DVA and CCA soils, respectively. Our data indicated that P. vittata efficiently solubilized non-labile As under P-limiting conditions without impacting its As depletion.

Although castor (Ricinus communis L.) oil has high commercial value for industrial uses as well as a feedstock for biodiesel, the United States has relied on imported castor oil since 1972. In Florida, the crop has been considered as an alternative crop to the more traditional agronomic row crops and would likely be produced under center pivot or other irrigation systems to maximize yield and fit with existing cropping systems. To develop an appropriate Kc value for the central Florida region, research was conducted at the University of Florida’s Plant Science Research and Education Unit in Citra, FL. Season-long crop transpiration was measured for the castor cultivar ‘Brigham’ in 2011 and 2012 and soil evaporation rates were quantified in 2012. Crop transpiration was obtained by sap flow analysis when the plots had reached complete canopy cover, were fully irrigated, and when daily solar radiation levels were at or above a historical radiation average to accurately reflect optimum growing conditions. Daily average plant transpiration (57,199 and 56,560 L ha−1 in 2011 and 2012, respectively) were predominantly greater than daily soil evaporation (38 L ha−1 in 2012), and as a result, the season long plant transpiration was the main factor included for the calculation of crop evapotranspiration (ETc). The ETc was evaluated against the reference evapotranspiration (ETo) from site specific meteorological data to calculate daily Kc values. The 10-day Kc averages were compared to published Kc values from the Food and Agriculture Organization (FAO) for castor. The crop developmental timeframes in this study were roughly aligned with the FAO timeframes when making these comparisons. The mid-season Kc values were similar to the FAO reference (1.19, Florida vs. 1.15 FAO ref.), but the late season Kc values for castor in Florida were higher as compared to the FAO reference (1.50 vs. 0.55, respectively). The increase in water use during this late season developmental period could be explained by a lack of physiological decline in this sub-tropical climate and continued irrigation application for this trial during the latter part of the season. These results provide appropriate Kc values for central Florida and will aid growers in irrigation decisions when producing castor in this region.

School cafeterias are a significant source of food waste and represent an ideal opportunity for diverting food waste from landfills. In this study, cafeteria waste audits were conducted at three Florida schools. Food waste comprised the largest fraction of school cafeteria waste streams, ranging from 47% to 58%, followed by milk, paper products (tissue, milk cartons, pasteboard, paper plates, and cardboard), and plastics (plastic wrap, packaging, and utensils). Metal and glass comprised the smallest fraction of the waste stream. Average total waste generation ranged from 50.5 to 137.6 g·student −1 ·day −1 . The mean generation rates for food waste ranged from 24.7 to 64.9 g·student −1 ·day −1 . The overall average for cafeteria waste generation among all three schools was 102.3 g·student −1 ·day −1 , with food waste alone contributing 52.2 g·student −1 ·day −1 . There are two primary approaches to diverting school food waste from landfills: reduction and recycling. Food waste can be reduced through educating students and staff in order to change behaviors that cause food waste. Food waste can be collected and recycled through composting or anaerobic digestion in order to generate beneficial end products, including soil amendments and bioenergy. Over 75% of the cafeteria waste measured in this study could be recycled in this manner.

Proper disposal of As-hyperaccumulator Pteris vittata biomass (Chinese brake fern) enhances its application in phytoremediation. The goal of this study was to optimize As removal from P. vittata (PV) biomass by testing different particle sizes, extractants, extraction times and solid-to-liquid ratios. PV biomass was extracted using different extractants followed by different Mg-salts to recover soluble As via precipitation. Water-soluble As in PV biomass varied from 6.8% to 61% of total As depending on extraction time, with 99% of As being arsenate (AsV). Extraction with 2.1% HCl, 2.1% H3PO4, 1 M NaOH and 50% ethanol recovered 81, 78, 47 and 14% of As from PV biomass. A follow-up extraction using HCl recovered 27–32% with ethanol recovering only 5%. Though ethanol showed the lowest extractable As, residual As in the biomass was also the lowest. Among the extractants, 35% ethanol was the best to remove As from PV biomass. Approximately 90% As was removed from PV biomass using particle size

Centrate from dewatering anaerobically digested municipal sludge is a particular concern in wastewater treatment, as it contains high ammonia concentrations and is often recycled to the head of the plant, reducing efficiency. Algae have the potential to remove ammonia from this wastewater, while producing biomass that can be used as an energy feedstock. In this research, an indigenous algal consortium was cultivated on municipal sludge centrate in a semi-continuous photobioreactor under natural light conditions. The goals of this research were to (1) enrich an algal consortium capable of growth on sludge centrate; (2) determine the main species of the consortium;(3) measure biomass, lipid production, and nutrient removal rates; and (4) develop a simple model to describe the system. The results suggested that Chlorella sp. was the dominant species (95 %) in the consortium. Mean biomass productivity was 5.2 g m−2 day−1, which was relatively high compared with other studies carried out with high ammonia strength wastewaters. Lipid production was low, comprising only 10 % of total biomass. The algal consortium effectively removed nutrients from the centrate, with observed mean removal efficiencies for total nitrogen, total phosphorus, and chemical oxygen demand of 65, 72, and 8 %, respectively. A simple irradiance-based model was developed from the fundamental Michaelis-Menten photosynthesis-irradiance (PI) response for photosynthetic organisms. A good fit to the experimental data was obtained with the irradiance-based model (R 2 = 0.96), indicating that the system was light limited. The results show that biomass production can be predicted based on irradiance only.

While castor (Ricinus communis L.) oil is an essential component in many industrial products, the U.S. currently imports all castor oil stocks due to the lack of domestic production of the crop since 1972. To reestablish U.S. production of castor, regional agronomic assessments of cultivars and management systems are required to assess the economic sustainability of the crop. A comparison of two castor cultivars (Hale and Brigham) and management systems using plant growth regulators and harvest aids was conducted at two different locations (PSREU and WFREC) within Florida during two years (2011 and 2012) with the goal of assessing yield potential and phenological development of the crop in this semi-tropical climate. Yields were low in comparison to other U.S. regions where the crop has been tested with the highest yields being 1357 kg ha−1 for Brigham at PSREU in 2011 and the lowest being 686 kg ha−1 for Brigham at PSREU in 2012. Mold observed on both cultivars and significant rates of shatter could have led to upwards of 60% yield loss, indicating that yield potential in the region may be much higher. Oil percentages on average across sites and years were very consistent between the cultivars, with 45.0 and 45.4% for Brigham and Hale, respectively. Typical growth patterns of height, leaf area index (LAI), reproductive development, and root architecture were characterized for the region. The maximum height recorded for either cultivar did not exceed 115.2 cm and the maximum seasonal LAI value was 2.87. Brigham produced between 3 and 8 more racemes than Hale by the end of the season, depending on the site/year. The application of a mepiquat chloride based plant growth regulator (PGR) did not reduce plant height at either location and had no consistent impact on photosynthetic capacity of the crop. The harvest aid paraquat led to over six times more leaf desiccation and leaf defoliation within 11 days after treatment and was more effective overall than the tribufos harvest aid.

Optimizing short-term solubilization is essential for high-rate anaerobic digestion of food waste. The purpose of this study was to measure the short-term kinetics of food waste solubilization and understand what mechanisms are responsible for driving food waste solubilization. Two solubilization assays were conducted to measure the solubilization of mechanically processed food waste. Three methods of mechanical grinding were utilized: an in-sink food disposer and a manual meat grinder with either small or medium size plate openings. A control assay was conducted to measure the release of endogenous soluble material into an aqueous medium. An enzyme assay was conducted to examine short-term food waste hydrolysis. The assays were diluted and buffered to prevent product and pH inhibition, respectively, and allow maximum solubilization to occur. Percent solubilization was calculated as the soluble chemical oxygen demand (COD) fraction of total COD. Data from the two assays were used to calculate the kinetics of endogenous solubilization and enzymatic hydrolysis. Regardless of grinding method, food waste was 27% solubilized within 1 h through endogenous solubilization. Enzymatic hydrolysis was responsible for an additional 29–31% solubilization by 4 h. This study showed that ground food waste was approximately 60% solubilized within 4 h under optimal conditions.

There is a pressing need for sustainable renewable fuels that do not negatively impact food and water resources. Algae have great potential for the production of renewable biofuels but require significant water and fertilizer resources for large-scale production. Municipal solid waste (MSW) landfill leachate (LL) was evaluated as a cultivation medium to reduce both water and elemental fertilizer demands of algae cultivation. Daily growth rate and cell yield of two isolated species of algae (Scenedesmus cf. rubescens and Chlorella cf. ellipsoidea) were cultivated in MSW LL and compared with Bold's Basal Medium (BBM). Results suggest that LL can be used as a nutrient resource and medium for the cultivation of algae biomass. S. cf. rubescens grew well in 100% LL, when pH was regulated, with a mean growth rate and cell yield 91.2% and 92.8% of those observed in BBM, respectively. S. cf. rubescens was more adaptable than C. cf. ellipsoidea to the LL tested. The LL used in this study supported a maximum volumetric productivity of 0.55 g/L/day of S. cf. rubescens biomass. The leachate had sufficient nitrogen to supply 17.8 g/L of algae biomass, but was limited by total phosphorus. Cultivation of algae on LL offsets both water and fertilizer consumption, reducing the environmental footprint and increasing the potential sustainability of algae-based biofuels.

Photosynthetic algae represent a large and diverse group of organisms that have only a limited history of characterization and exploitation. The application of resource production from algae is relatively untapped, with the potential to produce fuels, food, fibers and nutraceuticals on a large scale. Methods to screen for indigenous species of algae have improved and can allow communities to prospect for algae suited to regional needs. When cultured locally, indigenous algae are adapted to the prevailing regional abiotic and biotic factors. Native algae commonly inhabit local waste resources and pose no risk of becoming noxious invasives. Methods for culturing algae can utilize anthropogenic waste resources including wastewater nutrients and CO 2 from fossil fuel combustion. While genetic engineering may have a role in helping future algae production succeed, the majority of algae species have yet to be identified or characterized and the genetic diversity of these unknown species may offer significant but currently unknown benefits for bioresource production. Recalcitrant problems of culture stability, biomass density, harvesting, and product refining may be overcome by exploring native biological material. Selecting indigenous algae with intrinsic characteristics amenable to bioresource production and waste mitigation – phycoprospecting – is the most sustainable path forward for widespread algae-based bioresource development. Our recent efforts in phycoprospecting of local habitats revealed a diversity of algae with significant lipid content.

Hydrilla (Hydrilla verticillata) is one of the world's most problematic invasive aquatic plants. Although management of hydrilla overgrowth has often been based on use of chemical herbicides, issues such as the emergence of herbicide-resistant hydrilla biotypes and the need for in situ nutrient remediation strategies have together raised interest in the use of harvester machines as an alternative management approach. Using a life cycle assessment (LCA) approach, we calculated a range of net energy and economic benefits associated with hydrilla harvests and the utilization of biomass for biogas and compost production. Base case scenarios that used moderate data assumptions showed net energy benefit ratios (NEBRs) of 1.54 for biogas production and 1.32 for compost production pathways. NEBRs for these respective pathways rose to 2.11 and 2.68 when labor was excluded as a fossil fuel input. Base case biogas and compost production scenarios respectively showed a monetary benefit cost ratio (BCR) of 1.79 and 1.83. Moreover, very high NEBRs (3.94 for biogas; 6.37 for compost) and BCRs (>11 for both biogas and compost) were found for optimistic scenarios in which waterways were assumed to have high hydrilla biomass density, high nutrient content in biomass, and high priority for nutrient remediation. Energy and economic returns were largely decoupled, with biogas and fertilizer providing the bulk of output energy, while nutrient remediation and herbicide avoidance dominated the economic output calculations. Based on these results, we conclude that hydrilla harvest is likely a suitable and cost- effective management program for many nutrient-impaired waters. Additional research is needed to determine how hydrilla harvesting programs may be most effectively implemented in conjunction with fish and wildlife enhancement objectives.

article i nfo Article history: Received 27 September 2010 Accepted 27 September 2010 Greenhouse gas emissions inventories provide a baseline to develop mitigation projects for reducing emissions. However, a detailed inventory of livestock gas emissions is not available for Ecuador. This study attempts to fill this gap. The methodology selected comes from the 2006 Intergovernmental Panel on Climate Change guidelines toquantify emissions from thelivestock sector. Tier 1methodology wasimplemented using animal census data for the year 2000, and historical temperature data by province. The total methane emissions from enteric fermentation were 5596 GgCO2Eq.Methane emissions from manure came mainly from cattle and swine with 92.4 and 44.3 GgCO2Eq, respectively, and a livestock total of 182 GgCO2Eq. The total direct nitrous oxide (N2O) emissions from manure management were 172 GgCO2Eq, and total direct and indirect N2O emissions from manure deposited on soils by grazing livestock were 2176 GgCO2Eq. A further 103 GgCO2Eq of direct N2O emissions came from the application of confined-livestock manure to soils. We estimated the total potential reductions in emissions from capturing methane gas from anaerobic digestion of dairy, swine and poultry manure and substituting methane for liquefied petroleum gas (LPG) at 308 GgCO2Eq. The value of the methane produced could amount to US$ 77 M. Alternatively, that same methane gas could be used to generate 275 GWh of electricity. Additional benefits from anaerobic digestion of manure include the recovery of nutrients from the digested effluent, which could be used as biofertilizer and soil amendment. The capture of these greenhouse gases and the use of anaerobic digesters to produce energy and other products seem to have potential in Ecuador. However, lack of experience with anaerobic digestion and biogas production is a great limitation for the implementation of this technology. Also, anaerobic digester designs should be evaluated and modified to fit local needs given the variability of climatic and socio-economic conditions across the country.

There is a growing impetus to identify and develop bioenergy feedstocks that can be harnessed in ways that do not require major land-use intensification or use of food crops. Although invasive aquatic plants have long been regarded as an intriguing potential feedstock because of their high growth rate in natural water bodies, most contemporary management is based on plant control rather than utilization. This review presents a comparative life cycle overview of modern aquatic plant control and alternative bioenergy utilization programs, highlighting costs and benefits associated with both approaches. Given recent advances in harvester and bioenergy conversion technologies, it may be cost effective to incorporate utilization techniques in many water bodies, particularly if ancillary benefits associated with nutrient removal and greenhouse-gas reductions are given monetary credit. Pilot projects and site-specific evaluations are, however, needed to determine the ultimate scale in which bioenergy production ...

Biogas is a renewable source of natural gas produced by the microbial degradation of organic matter in a process called anaerobic digestion. While any organic material may be a feedstock for anaerobic digestion, waste organic matter represents a vast potential for sustainable energy production. Food waste, in particular, is a relatively untapped resource. Large amounts of food waste are produced at campus dining halls and other food service facilities. A case study was undertaken to determine biogas production and implementation potential at the University of Florida's Broward Dining Hall. Food waste quantity and current disposal methods were determined. The waste was analyzed for organic matter content and potential biogas yield. Food waste was digested in a small-scale anaerobic digester. The study demonstrated that converting food waste to biogas could provide significant supplemental energy to the dining hall and provide a closed-loop system for sustainable food waste management. By using biogas produ...

Our recent paper advocating adaptive management of invasive nonnative species (INS) in Kings Bay, Florida received detailed responses from both Daniel Simberloff, a prominent invasion biologist, and Mark Sagoff, a prominent critic of invasion biology. Simberloff offers several significant lines of criticism that compel detailed rebuttals, and, as such, most of this reply is dedicated to this purpose. Ultimately, we find it quite significant that Simberloff, despite his other stated objections to our paper, apparently agrees with our argument that proposals for alternative management of established INS (i.e., alternatives to minimization/eradication) should not be rejected on an a␣priori basis. We argue that more specific development and application of adaptive approaches toward INS management, whether in Kings Bay or other appropriate case studies, would be facilitated if ecosystem managers and invasion biologists follow Simberloff’s lead on this key point. While Sagoff largely shares (and, indeed, served as a primary source for developing) our general arguments that challenge common moral and scientific assumptions associated with invasion biology, he does question our suggestion that participatory adaptive management provides an appropriate framework for approaching environmental problems in which science and politics are inherently entangled. We attempt to answer this criticism through a brief sketch of what participatory adaptive management might look like for Kings Bay and how such an approach would differ from past management approaches.

This paper develops the outlines of a pragmatic, adaptive management-based approach toward the control of invasive nonnative species (INS) through a case study of Kings Bay/Crystal River, a large artesian springs ecosystem that is one of Florida’s most important habitats for endangered West Indian manatees (Trichechus manatus). Building upon recent critiques of invasion biology, principles of adaptive management, and our own interview and participant–observer research, we argue that this case study represents an example in which rigid application of invasion biology’s a␣priori imperative to minimize INS has produced counterproductive results from both an ecological and social standpoint. As such, we recommend that INS control in Kings Bay should be relaxed in conjunction with an overall program of adaptive ecosystem management that includes meaningful participation and input from non-institutional stakeholders. However, we also note that adaptive management and INS control are by no means mutually exclusive, in Kings Bay or elsewhere. Instead, we suggest that adaptive management offers a means by which INS control efforts can emerge from—and be evaluated through—ongoing scientific research and participatory dialogue about the condition of specific places, rather than non-contextual assumptions about the harmfulness of INS as a general class.

Recovery of phosphorus (P) from flushed dairy manure in an easily-dewatered form would enable farmers to manage P as a resource rather than land-apply it in excess at environmental risk. The purpose of this study was to evaluate (i) the feasibility of P recovery and (ii) the form of recovered P from flushed dairy manure wastewater using crystallization in a fluidized-bed reactor. Wastewater was pumped directly from a dairy farm reservoir and continuously fed in parallel through four bench-scale fluidized-bed reactors deployed on-site. Chemical additives (NaOH and MgSO4) required for recovery were injected directly into the zone of fluidization. Recovered P forms were assessed by X-ray diffraction, scanning electron microscopy, and micro-elemental analysis. Recovery of P as poorly-crystalline hydroxylapatite (HAP) was documented in coatings ultrasonically removed from quartz seed grains following fluidization at elevated pH in conjunction with MgSO4 injection. Addition of MgSO4 was required to prevent CaCO3 precipitation upon pH elevation and hence enable calcium phosphate precipitation. It is likely that MgSO4 inhibited CaCO3 via formation of MgCO3 (aq). Periclase (MgO), which also served as an effective seed material, generated sufficient alkalinity at grain surfaces to precipitate abundant CaCO3 and in some cases detectable Ca phosphate even without NaOH addition to elevate pH of bulk solution.

The Kings Bay, Crystal River complex, located in Citrus County, Florida, is one of the world’s largest spring-fed ecosystems and a critical warm-water refuge for endangered Florida manatees. Unfortunately, large areas of Kings Bay are currently in a state of ecological degradation characterized by smothering mats of the filamentous cyanobacterium Lyngbya wollei. The causes of this ecosystem shift are not well understood, although it is often suggested that human-caused nutrient loading into the Bay combined with intermittent saltwater intrusions from storm surges may be responsible. In this article, we present results from interviews with local citizens, a review of aquatic plant literature, and research into the history of ecological change in Kings Bay. Our work indicates that management efforts to eradicate invasive exotic aquatic species may also have played an important role in the dominance of L. wollei. We suggest that future restoration efforts should follow a logic of “alternative stable states” that focuses primarily on the recovery of desired ecosystem functions and relaxes the assumption that exotic plants should be minimized. The Kings Bay case study points toward a more adaptive conception of ecological restoration, one informed by local knowledge and open to the utilization of established exotic plants as a tool for maintaining or restoring important ecological attributes.

Eighteen wastewater treatment systems were operated for one year to investigate phosphorus (P) removal. Systems paired co-treatment reactors containing iron or calcium drinking water treatment residuals with vertical-flow constructed wetland mesocosms planted with Schoenoplectus tabernaemontani (K.C. Gmel.) Palla. For secondary municipal wastewater, soluble reactive P (SRP) concentrations were reduced from 0.70 to 0.03 mg L −1 (95%) or 0.01 mg L −1 (98%) by systems with the calcium or iron co-treatments, respectively (compared to 0.09 mg L −1 or 87% by controls). Total P (TP) concentrations were reduced from 1.00 to 0.07 mg L −1 (93%) and 0.05 mg L −1 (95%) by the same treatments (compared to 0.16 mg L −1 or 84% by controls). For anaerobically digested dairy wastewater, SRP was reduced from 7.68 to 6.43 mg L −1 (16%) or 5.95 mg L −1 (22%) by the systems with calcium or iron, respectively (compared to 7.37 mg L −1 or 4% by controls). For this wastewater, the TP was reduced from 48.5 to 22.5 mg L −1 (53%) and 22.7 mg L −1 (53%) by the same treatments (compared to 24.1 mg L −1 or 50% by controls) but performance improved substantially with a design modification tested.

The characteristics of flushed dairy manure after primary treatment at a Florida dairy were monitored daily over a 1-year period along with cow numbers and water use, with the aim of developing fixed-film anaerobic digestion of flushed dairy manure wastewater (FDMW). Primary treatment included screening through a mechanical separator followed by sedimentation. The FDMW exhibited average total solids (TS), volatile solids (VS) and total chemical oxygen demand (COD) levels of 3580, 2210 and 3530 mg l � 1 , respectively, for a milking herd average of 359 cows and a wastewater production of 502 m 3 d � 1 . Analyses of FDMW parameters and manure excretion estimates indicated that 53% of the TS, 40% of the VS and 58% of the total COD remained in the wastewater after screening and sedimentation. The separation of fibrous solids increased the COD to VS ratio of the FDMW. Wastewater temperature was found to significantly affect both the separation of TS, VS, and total COD, and the partitioning of wastewater parameters between the particulate and soluble phases. Higher FDMW temperatures tended to reduce TS, VS, and total COD removal efficiencies. The ratio of soluble COD to dissolved VS increased with temperature, while the ratio of particulate COD to volatile suspended solids decreased, indicating that significant levels of biological activity occurred in the sedimentation basin at higher temperatures. The VS measurement does not accurately determine the methane potential of components in FDMW compared to COD measurements. In spite of the fact that 60% of the VS is removed by screening and sedimentation, the major portion of the methane potential remains in the wastewater since the solids that are removed are relatively non-degradable fibres and do not contribute to methane production. Model equations were developed to predict total COD levels in flushed dairy manure wastewater as a function of fresh flushwater usage per animal unit for similar dairy operations, providing an important design parameter for implementation of fixed-film anaerobic digestion systems.

An economical bioreactor designed for evaluating the biogas potential of particulate biomass is described. The bioreactor uses a simple stirring apparatus, called the Bordeaux stirrer, to enable gas-tight mixing of fermentation cultures. The apparatus consists of a low-rpm motor connected to a bent steel stir rod, which is placed in a length of flexible plastic tubing inserted through a rubber stopper in a gas-tight manner. This stirrer is suitable for providing intermittent or continuous mixing in bench-scale anaerobic cultures containing particulate biomass. The reactor system may be operated as a batch-fed or semi-continuously fed digester. This communication documents the advantages of the stirring apparatus, describes the details of reactor fabrication and operation, and outlines the type of experimental work for which the bioreactor is suitable.

The potential of three floating aquatic macrophytes to improve the water quality of anaerobically digested flushed dairy manure wastewater (ADFDMW) was evaluated. In undiluted ADFDMW (total chemical oxygen demand 2010 mg/l), growth of water hyacinth (Eichhornia crassipes) was inhibited and both pennywort (Hydrocotyle umbellata) and water lettuce (Pistia stratiotes) failed to grow. In a 1:1 dilution of ADFDMW, all three plants grew successfully. However, growth of pennywort and water lettuce was limited while water hyacinth growth was robust. High salinity appears to be the principal reason for inhibition, as well as possibly uncharacterized soluble compounds. In terms of reductions in nutrients, chemical oxygen demand (COD), solids and salinity, water hyacinth performed better than water lettuce and pennywort in diluted ADFDMW. Reduction in nutrients and COD followed first-order kinetics, with water hyacinth exhibiting the highest rates. For water hyacinth, total Kjeldahl nitrogen was reduced by 91.7%, ammonium by 99.6%, total phosphorus by 98.5%, and soluble reactive phosphorus by 96.5% in 31-day batch growth. A polyculture of the three plant species in 1:1 diluted ADFDMW exhibited the next best performance. The high biomass yield of the diluted water hyacinth culture corresponded with high EC and Na + reductions, suggesting that EC measurement might be a simple tool to monitor performance of water hyacinth growth and nutrient reduction under high plant growth rate conditions.

Growing algae to scrub nutrients from manure presents an alternative to the current practice of land application and provides utilizable algal biomass as an end product. The objective of this study was to assess algal growth, nutrient removal, and nitrification using higher light intensities and manure loading rates than in the previous experiments. Algal turfs, with periphyton mainly composed of green algal species, were grown under two light regimes (270 and 390 μmol photons . m - 2 . s - 1 ) and anaerobically digested flushed dairy manure wastewater (ADFDMW) loading rates ranging from 0.8 to 3.7 g total N and 0.12 to 0.58g total P . m - 2 . d - 1 . Filamentous cyanobacteria (Oscillatoria spp.) and diatoms (Navicula, Nitzschia, and Cyclotella sp.) partially replaced the filamentous green algae at relatively high ADFDMW loading rates and more prominently under low incident light Mean algal production increased with loading rate and irradiance from 7.6 ′ 2.71 to 19.1 ′ 2.73 g dry weight . m - 2 . d - 1 . The N and P content of algal biomass generally increased with loading rate and ranged from 2.9%-7.3% and 0.5%-1.3% (by weight), respectively. Carbon content remained relatively constant at all loading rates (42%-47%). The maximum removal rates of N and P per unit algal biomass were 70 and 13 mg . g - 1 dry weight . m - 2 . d - 1 , respectively. Recovery of nutrients in harvested algal biomass accounted for about 31%-52% for N and 30%-59% for P. Recovery of P appeared to be uncoupled with N at higher loading rates, suggesting that algal potential for accumulation of P may have already been saturated. It appears that higher irradiance level enhancing algal growth was the overriding factor in controlling nitrification in the algal turf scrubber units.

Livestock wastes are potential sources of endocrine disrupting compounds to the environment. Steroidal estrogen hormones such as estradiol, estrone, and estriol are a particular concern because there is evidence that low nanogram per liter concentrations of estrogens in water can adversely affect the reproductive biology of fish and other aquatic vertebrate species. We performed a literature review to assess the current state of science regarding estrogen physicochemical properties, livestock excretion, and the fate of manure-borne estrogens in the environment. Unconjugated steroidal estrogens have low solubility in water (0.8-13.3 mg L(-1)) and are moderately hydrophobic (log Kow 2.6-4.0). Cattle excrete mostly 17alpha-estradiol, 17beta-estradiol, estrone, and respective sulfated and glucuronidated counterparts, whereas swine and poultry excrete mostly 17beta-estradiol, estrone, estriol, and respective sulfated and glucuronidated counterparts. The environmental fate of estrogens is not clearly known. Laboratory-based studies have found that the biological activity of these compounds is greatly reduced or eliminated within several hours to days due to degradation and sorption. On the other hand, field studies have demonstrated that estrogens are sufficiently mobile and persistent to impact surface and groundwater quality. Future research should use standardized methods for the analysis of manure, soil, and water. More information is needed about the types and amounts of estrogens that exist in livestock wastes and the fate of manure-borne estrogens applied to agricultural lands. Field and laboratory studies should work toward revealing the mechanisms of estrogen degradation, sorption, and transport so that the risk of estrogen contamination of waterways can be minimized.