Oak Wood Chips Research Articles

Interlaboratory Evaluation of Bretziella fagacearum Molecular Detection Assays to Guide the eDNA Monitoring of Oak Wilt Disease

ABSTRACTOak wilt disease, caused by the fungus Bretziella fagacearum, can kill mature red oaks within months of infection, severely affecting biodiversity, landscapes, and industries. The disease, originally only present in the United States, was officially reported for the first time in Canada in June 2023. The aim of this study was to suggest a standardized assay and sample processing method to optimize oak wilt detection both in infection centers and ahead of the disease front. Two previously published molecular assays, a Nested PCR and a TaqMan qPCR, were compared to detect B. fagacearum in a variety of samples in a ring trial across five laboratories. Sample types investigated included eDNA from trapped insect vectors (sorted insects and bulk content from traps), infested and healthy oak wood chips, and B. fagacearum conidia dilutions. Results demonstrated that both Nested and TaqMan assays can be used for molecular confirmation of oak wilt, and results are reproducible across different labs. There is a general agreement between both detection assays when testing true‐positive and true‐negative samples. Both methods demonstrated overall good accuracy. The TaqMan assay was more sensitive and detected lower amounts of DNA target. Both tests were 100% specific to oak wood samples, which was the best sample type to use for detection. In general, samples with high Cts were more prompted to yield false negative Nested results. Detecting oak wilt from bulk insect samples was by far more rapid than sorted sap beetles, but resulted in lower detection signals, especially with the Nested assay. The time‐period when the insect traps were set up also had considerable influence on detection results. We hope this study helps to formulate guidelines in oak wilt detection and biosurveillance management.

Preliminary Study of the Effect of Short Maceration with Cherry and Oak Wood Chips on the Volatile Composition of Different Craft Beers

In the last few years, the production and consumption of craft beers has increased notably. However, there is restricted knowledge about the potential impact of chips from different wood species on beer quality. Thus, this work aimed to evaluate the effect of the addition of wood chips from cherry and oak species—after the fermentation was completed and during a brief maceration time—on the volatile composition of three different beer groups (Ale, Lager, and Porter) through a headspace solid-phase dynamic extraction (HS-SPDE) and GC-MS analysis. Fifty-six volatile compounds from different chemical families (esters, alcohols, terpenes, acids, aldehydes, ketones, and pyrazines) were detected, identified, and considered in this study. In general, the volatile composition of the beers macerated with wood chips was very similar to that of the control beers. However, the control beers showed higher volatile compound levels. The results suggest potential interactions between beer volatile compounds and the wood chips during maceration. The outcomes of this research could be of practical interest to brewers since they could improve the knowledge of the impact of short-time contact and low wood chip concentration on the volatile composition of different craft beers.

Gasification of MDF residue in an updraft fixed bed gasifier to produce heat and power via an ORC turbine

Biomass, which is a renewable resource, is regarded as an essential energy source due to its accessibility and abundance. In this study, the gasification of wood-based biomass wastes from the medium density fiberboard (MDF) facility was carried out and investigated utilizing an updraft fixed bed gasifier. The feeding capacity of the upstream gasifier is 2100 kg/h. MDF wastes are loaded into the system with feeding capacities of 1500, 1750 and 2100 kg/h. As a reference, the system has also been tested with oak wood chips at a maximum rate of 2100 kg/h. Produced syngas production rate to biomass waste is approximately 2.5 Nm3/kg. The measured gas compositions are CO, CO2, CH4, H2, O2 and N2. Test results with 2100 kg/hMDF wastes have similar gas composition compared to the test results with oak wood chips. The quality of the syngas produced by gasification is directly related to the fuel. It has been observed that the efficiency of the gasification process can be directly or indirectly impacted by the properties of the fuel, such as the moisture content, chemical compositions, and size. The temperature of the produced gas is approximately 430 °C, and it isdirectly combusted with tars and soot it contains to ensure that no chemical energy is lost. The thermal gasification system converts approximately 88% by weight of MDF residue to syngas. The calorific value of produced syngas is obtained between 6.0 and 7.0 MJ/Nm3. The hot syngas containing tars produced from the gasifier was directly burned in the thermal oil heater retrofitted to vortex syngas burner to recover thermal energy, which was then utilized in the production of energy via an ORC turbine. The thermal oil heater has a thermal capacity of 7MWh and the power generation capacity of the ORC turbine is 955 kW of electricity.

Removal of NO at low concentrations from polluted air in semi-closed environments by activated biochars from renewables feedstocks

Efficient measures are urgently required in large cities for nitric oxide (NO) elimination from air in urban semi-closed environments (parking lots and tunnels), characterized by low NO concentrations (<10 ppmv) and temperatures. One of the most promising abatement alternatives is the NO oxidation to NO2, which can be further easily captured in an alkali solution or over a porous solid. However, most of the research devoted to this topic is focused on the elimination of NO from fuel exhaust gases, with high NO concentrations (400–2000 ppmv). In this work, sustainable and low-cost activated biochars of different origin and having very different ash contents were employed in NO removal at very low concentrations. Thus, low ash content forestry (oak woodchips, OAK) and high ash content from agriculture (oilseed rape straw, OSR) biochars were subjected to physical activation with CO2 at 900 °C (OAK550-A900CO2 and OSR700-A900CO2, respectively). The NO removal performance tests of such activated carbons were carried out at different experimental conditions: i.e., temperature, relative humidity (0–50 vol% RH), NO-containing gas (N2 or air), amount of activated carbon, and NO concentration, to assess how the activated biochar properties influence their NO removal capacity. The sample OSR700-A900CO2 contained a higher population of oxygen surface functionalities, which might play an important role in the NO removal efficiency in dry conditions since they could assist NO oxidation on carbon active sites when used above room temperature (50–75 °C). However, at room temperature (25 °C), the presence of narrow micropore size distribution at 6 Å became a more relevant property, since it facilitates an intimate contact between NO and O2. Accordingly, the activated biochar from OAK was much more efficient, achieving complete removal of NO from air flow (dry or with 50 vol% RH) at 25 °C during 400 min of testing, making it an ideal candidate as biofilter for purifying air streams of semi-closed spaces contaminated with low concentrations of NO.

Ultrasound and microwave techniques as physical methods to accelerate oak wood aged aroma in red wines

The feasibility of accelerating the release of volatile compounds of oak wood chips and aged aroma in wines by ultrasounds and microwaves techniques has been assessed.Despite the influence of the oak wood origin on the extraction of volatile compounds, results showed that wines subjected to treatments of ultrasounds 400 W during 12 h with pulses on/off each hour and microwaves 700 W for 20 min reached similar concentrations of compounds released from oak chips in wines macerated for 8 days. Those wines treated with microwaves exhibited more oak wood related compounds, but ultrasounds enhanced the extraction of more relevant compounds from a sensorial point of view. Consequently, wines with an accelerated ageing assisted by ultrasounds acquired more pronounced aged aromas. Therefore, the use of ultrasound to assist ageing process resulted in an accelerated acquisition of aged aroma which may resemble or even enhance the sensorial profile of wines in contact with oak chips in shorter times.

Autocatalytic properties of biochar during lignocellulose pyrolysis probed using a continuous reaction system

The autocatalytic role of the biochar formed during the pyrolysis of oak woodchips has been in situ assessed using a continuous reaction system. To that end, the evolution of the product distribution along the time on stream was evaluated at different temperatures ranging between 300 and 550 °C. When working at low temperatures (300 and 350 °C), the system operates under almost steady state conditions with little variations in the yield and composition of the pyrolysis fractions. However, at higher temperatures, a progressive reduction in the bio-oil* yield (bio-oil on a water-free basis) is observed along the time on stream, which is accompanied by a significant increase in the gas production, mainly as a result of the enhanced generation of CO and CO2. Within the liquid organic fraction, these transformations cause a gradual reduction in its oxygen content and affect to a greater extent the heavy/oligomeric components. Likewise, noticeable variations are denoted along the time on stream for other bio-oil* components, such as carboxylic acids, sugars, and oxygenated aromatics. Additional pyrolysis tests, performed using two biochars with different K content as external catalysts, confirm that the origin of the biochar catalytic effects can be linked with its relatively high AAEMs (alkali and alkaline earth metals) content. Nevertheless, the contribution of the biochar carbonaceous matter should be also taken into account since it may retain many of the species present in the pyrolysis vapours, in particular the heaviest components, thus facilitating their subsequent conversion.

Exploring Deep Eutectic Solvents for the Extraction of Lignocellulosic Materials (3) : Study on Precipitation Solvents for Lignin Recovery from the Black Liquors of Sawtooth Oak Pulping

This study evaluated whether lignin can be recovered in three different deep eutectic solvent (DES) black liquors by adding various precipitation solvents. Three DES black liquors prepared by cooking the oak wood chip with carboxylic acid-based DES, phenol-based DES, and alkaline organic compound-based DES were used in this study. Six solvents were used as precipitation solvents, including distilled water, ethanol, acetone, 5% sodium hydroxide, 5% sulfuric acid, and 20% acetic acid.BRThe solvent causing precipitation in each black liquor differed depending on the types of DES used to extract the wood chips. The precipitation efficiency of each solvent was also varied. In the case of the carboxylic acid-based DES black liquor, distilled water had the best precipitation characteristics. In contrast, it was found that acetone for the phenol-based DES black liquor, and 20% acetic acid solution for the alkaline organic compound- based DES black liquor were the most suitable precipitation solvents. It is expected that lignin recovery in the DES black liquor is relatively simple by various solvent treatments.

Combustion and Emission Analysis of Spent Mushroom Compost and Forestry Woodchip for Management and Energy Production

Forestry woodchip and spent mushroom compost have commercial potential as sustainable residues in biological and chemical processes for energy production. This study focuses on the evaluation of agri-food industry waste energy valorization, with the aim to reduce the valuable biomass utilization for energy production without decreasing the process quality, thereby pursuing economic and environmental advantages. Burning trials were conducted in a fluidized bed biomass plant provided with emission abatement systems. The biomass mixture used for combustion was composed of pine and oak woodchip and spent mushroom compost. The biomass used was first characterized through compositional and energetic analysis, and subsequently, during the burning tests, a monitoring sampling campaign was carried out to analyze the gas and particles emission. Optimal combustion conditions were observed during combustion, with good oxidation of the organic material, relatively high CO2 production, and low CO concentration in flue gas. Nevertheless, SO2 concentrations in the combustion flue gas are greater than those found in the combustion of the most commonly used biomasses. In fact, the mixture compositional characterization revealed a non-negligible concentration of sulfur, which explains the high values of SO2 detected in emission. The obtained results confirm that controlled combustion, together with suitable biomasses utilization, preliminary characterization, and emission monitoring, are essential practices for the realization of a sustainable process, both from an energy and environmental point of view.

Woodchips bioretention column for stormwater treatment: Nitrogen removal performance, carbon source and microbial community analysis

This study chose Oak woodchips and gravel as media filter to enhance the denitrification in the bioretention system (saturated zone 7.7 L) treating synthetic stormwater runoff. It revealed that the denitrification process mainly occurred during the drying phase and enlarging volume of saturated zones to retain more stormwater during storm event was the direct method to promote nitrogen removal of the bioretention system. Nevertheless, it was noted that the nitrogen and dissolved organic carbon would be released into the effluent during the wetting period. The denitrification rate with different nitrate nitrogen (NO3–N) concentrations did not show the obvious change with zero order kinetics constant of 2.91 mg/L∙d on average. Furthermore, it confirmed that woodchips were degraded and converted to volatile fatty acids (VFAs), especially acetic acid as carbon source, further utilized by the denitrifying bacteria, such as Dechloromonas, Acidoborax, Pseudomonas, Denitratisoma and Acinetobacter. In addition, genera of Lachnospiraceae and Lactobacillus, which had the ability to degrade the macromolecular organic components into low molecular VFAs, were observed in the woodchips bioretention system.

Mycelium-composite panels for atmospheric particulate matter adsorption

Mycelium composites grow in a symbiotic relationship with the substrate forming entangled networks of branching fibers. The structure of mycelium resembles filter sheets used in air filtration systems. Owing to their porous character, mycelium composites have been studied and developed as sound absorbent materials, insulation materials, and fire-resistant materials. Herein, we investigated the potential utilization of the filter-like, porous characteristics of mycelium for adsorbing atmospheric particulate matter (PM).First, we compared the PM adsorption performance of mycelium composites grown on four different substrates (hemp, rice straw, lacquer tree wood chips, and oak wood chips) with a widely used architectural exterior material, a stone panel (Pocheon granite). Second, we examined the micro-morphology of the mycelium composite panel surfaces by capturing images at 200x and 1000x using scanning electron microscopy. Third, we examined the water absorption rate of the mycelium composite panels with different substrates.The PM adsorption performance of the mycelium composites were superior to that of the Pocheon granite. The PM adsorption performance of the mycelium composite panels varied depending on the type of the substrate. However, the relationship between the micro-morphology of the surface and the PM adsorption performance could not be defined. We also observed that the mycelium composite panels with the higher PM adsorption performance exhibited a higher rate of water absorption. This study shows that mycelium composite panels have potential to be developed as atmospheric PM adsorbing material.

Extraction of volatile aroma compounds from toasted oak wood using pulsed electric field

The effect of pulsed electric field (PEF) on the extraction of volatile compounds from toasted oak wood chips immersed in various aqueous ethanol solutions (5%, 12%, 50%, and 70% vol/vol) was determined by Gas chromatography/mass spectrometry (GC/MS) after ultrasound-assisted extraction. PEF treatment showed the highest impact in the 5% solution, increasing vanillin, syringaldehyde, oak lactone (cis- and trans-), and furfural by 75%, 371%, 13%, and 50%, respectively. PEF was also tested on Agiorgitiko red wine and on malt and wine distillates. In wine distillate, 4-vinylguaiacol was also detected. For red wine, a PEF of 1.2 kV/cm increased the efficiency of extraction of wood aroma compounds from 5% to 200%. Differences in the extracted volatile compound concentrations between the control and PEF-treated samples were also observed in the malt and wine distillates. The sensory evaluation showed that the PEF-treated malt was similar to an aged whiskey, having nuances of toasted oak. Practical applications This work was done as a preliminary investigation for our on-going research into the application of PEF technique for the extraction of aromatic compounds from oak wood, and the acceleration of both wine and malt distillate aging. The findings suggest that PEF could be introduced in wine, brandy, and whiskey industry as a novel technology for the acceleration of the aging process.

Biological Nitrate Removal With Emerald Ash Borer-Killed Ash and High-Tannin Oak Woodchips

Two common tree species, ash (Fraxinus sp.) and oak (Quercus sp.), could provide readily available media for denitrifying bioreactors that use wood-based carbon for biological nitrate treatment. However, it is not known if the wood from Emerald Ash Borer-killed (EAB-killed) ash trees is an effective carbon source for nitrate removal compared to other wood species or if the high-tannin nature of oak inhibits denitrification potential. This lab-scale study showed that EAB-killed ash woodchips did not significantly differ in nitrate removal or denitrification potential compared to a commercially available blend of hardwood chips. However, neither treatment performed as well as oak woodchips in these metrics. Use of high-tannin oak in bioreactors is currently restricted by a federal standard in the United States. Ash woodchips beneficially exhibited the lowest nitrous oxide production potential, and their dissolved phosphorus leaching fell within the range of other woodchip types. Emerald ash borer-killed ash wood could be an effective source for denitrifying bioreactors located within affected regions and oak woodchips merit additional investigation for the application of denitrifying bioreactors.

Impact of oak (&lt;i&gt;Q. pyrenaica&lt;/i&gt; and &lt;i&gt;Q. pubescens&lt;/i&gt;) and cherry (&lt;i&gt;P. avium&lt;/i&gt;) wood chip contact on phenolic composition and sensory profile evolution of red wines during bottle storage

The majority of published work has studied the impact of wood chips on red wine composition by conducting analyses during wood chip contact or immediately after the removal of chips from wine. Less attention has been directed at the potential influence of prior chip-wine contact on the further phenolic and sensory evolution of red wines during bottle storage. Therefore, this work focuses on the evolution over a period of 18 months of several phenolic parameters and sensory characteristics of bottled Touriga Nacional red wines that had previously been in contact with toasted wood chips from cherry (Prunus avium) and two oak species (Quercus pyrenaica and Quercus pubescens) during 30 days of pre-bottling storage. Various global phenolic parameters, colour properties, individual anthocyanin content and sensory profile of the wines were studied at 6, 12 and 18 months of bottle storage. The results showed less decrease in the phenolic composition and red colour of wines which had prior contact with oak chips, as well as a less developed brown colour during bottle storage, compared to the wine previously in contact with cherry chips and the control wine. In addition, wine previously in contact with cherry chips always showed an evolution similar to the control wine. From a sensory point of view, the wines previously in contact with oak wood chips showed a tendency for higher aroma scores for “vanilla” and “coconut” descriptors and lower scores for “brown colour” during bottle storage than wines previously in contact with cherry chips and the control wine. The outcomes of this research could be of practical interest to winemakers since they could improve the knowledge of the impact of prior contact with wood chips in the future evolution of the red wines during bottle storage.

Reusability of Immobilized Cells for Subsequent Balsamic-Styled Vinegar Fermentations

Cell immobilization is a process augmentation technique aimed at improving microbial survival and activity under stressful conditions. It offers the opportunity to reuse the immobilized cells for several fermentation cycles. The present study investigated the use of recycled cells entrapped in calcium-alginate beads and cells adsorbed on corncobs (CC) and oakwood chips (OWC) in subsequent fermentation cycles for balsamic-styled vinegar (BSV) production. Sugars, pH, alcohol and total acidity were monitored during fermentation. Microbial activity and product formation declined when immobilized cells were reused for the second cycle for CC and OWC fermentations. Recycled cells entrapped in Ca-alginate beads completed the second cycle of fermentations, albeit at reduced acetification rates compared to the first cycle. Scanning electron microscope (SEM) imaging results further showed a substantial the structural integrity loss for Ca-alginate beads after the first cycle, and with minor changes in the structural integrity of CC. The OWC displayed a similar morphological structure before and after the first cycle. The sensory results showed that BSV produced using immobilized cells with Ca-alginate beads and CC was palatable, while those produced using OWC had negative attributes. Ca-alginate beads offered better protection for the fermentation consortium for culture reusability in BSV fermentations.

Removal behavior of gaseous furfural using a biofilter packed with perlite, ripe compost, and oak woodchips

Furfural is a toxic compound that is widely used in various industries. Prolonged inhalation exposure to this pollutant, especially at workplaces, can induce detrimental health effects. Therefore it is important to remove it from the environment. The present study aimed to investigate furfural removal from polluted air streams using a biofilter system. In this regard, a 4-section biofilter packed with perlite, ripe compost, and oak woodchips was operated for a 108 day-period under different operating conditions. The effects of pH (natural and acidic), inlet concentration (18.8–81.6 mg m−3), the height of biofilter layers (4 sections), and empty bed residence times (EBRTs) of 120, 70, and 30 s on removal efficiency (RE) of the biofilter were evaluated. All sampling and measurements were performed according to standard methods. The RE values under neutral and acidic conditions were 80 and 65 %, respectively. At furfural inlet concentrations in the ranges of 18.8–21.3, 35.25–42.7, and 78.4–81.6 mg m−3, the RE values were 81, 68, and 57 %, respectively. Also, the RE values at EBRTs of 120, 70, and 30 s were 83, 73, and 61 %, respectively. About half of the total RE was related to the first section of the biofilter, where the number of bacterial (6.2 log10 CFU g-1) and fungal (5.8 log10 CFU g-1) were higher than the other sections. Due to the high RE (72 %) and low pressure drop (below 43 Pa m-1) of the biofilter, it can be concluded that biofiltration is a suitable process to remove furfural from the air.

Mechanical and formaldehyde-related properties of medium density fiberboard with zeolite additive

Zeolite was investigated as a potential component in the production of medium-density fiberboard (MDF). A mixture of beech (40%), oak (30%), and pine (30%) wood chips was used for fiber production. Chips were cooked for 4 min in an Asplund defibrator with a vapor pressure of 8 bar, and a temperature of 180 °C. Chemicals were added on fibers in the blow line. The resins were added at 11 wt% based on oven-dried wood fibers. Ammonium sulphate was added at 0.72 wt% based on resins. Paraffin wax was added as 1.8 wt% based on resin. Zeolite was prepared in a separate tank for its use instead of lignocellulosic fibers in the production of 1 m³ MDF. The fibers were dried to 12% moisture. A temperature of approximately 190 °C and a pressure of approximately 32 kg.m-² were applied to the mixture for 280 s to make MDF panels (500 x 490 x 14 mm). Mechanical properties of MDF boards were significantly increased for bending (MOE) and elastic modulus (MOR), but a little negatively affected on internal bond (IB), physical properties were negatively increased thickness swelling (ThS) and water absorption (WA). Consequently, increasing zeolite minerals in MDF boards showed best results of formaldehyde emission properties of MDF.

Process Intensification: Activated Carbon Production from Biochar Produced by Gasification

The recent increase in the number of policies to protect the environment has led to a rise in the worldwide demand for activated carbon, which is the most extensively utilised adsorbent in numerous industries and has a high probability to be used in the energy and agriculture sectors as electrodes in supercapacitors and for fertiliser production. This paper is about the production of activated biochar from oak woodchips char generated by an updraft fixed bed gasifier reactor. Following this, using steam as activating agent and thermal energy from produced synthesis gas (syngas), the resulting highly microporous carbonaceous biomaterial was subjected to physical activation at 750ºC. The properties of activated biochar include adsorption or desorption of nitrogen to identify the physical adsorption and surface area measurement, thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The biochar surface area, generated as a result of the gasification process, showed substantial improvement after steam activation. Also, significant discrepancies were obtained from the surface volume and areas of biochar byproducts from the gasifier and activated biochar obtained by steam activation after the gasification treatment (total pore volume 0.022 cm3g−1and 0.231 cm3g−1, Brunauer–Emmett–Teller (BET) surface area 21.35 m2g−1and 458.28 m2g−1, respectively). The two samples also yielded noteworthy differences in performance. As a consequence, it may be concluded that the kinetics of steam gasification is quicker and more efficient for the conversion of biochar to activated carbon. The pore sizes of the carbon produced by steam activation were distributed over a wide spectrum of values, and both micro- and mesoporous structures were developed.

Use of Oak and Cherry Wood Chips during Alcoholic Fermentation and the Maturation Process of Rosé Wines: Impact on Phenolic Composition and Sensory Profile.

There is a lack of knowledge about the use of different wood species on rosé wine production. Thus, this work focused on the impact of the addition of wood chips from oak and cherry trees during the alcoholic fermentation and maturation process on rosé wine characteristics. Therefore, phenolic composition and sensory characteristics were monitored during the rosé wines’ production. The use of wood chips during alcoholic fermentation induced a significant increase of phenolic content in rosé musts. During rosé wine maturation, the wood chip contact induced significantly higher values of colored anthocyanins, color intensity, and polymeric pigments, and significantly lower values of color hue in the corresponding rosé wines. In terms of sensory profile, a tendency for lower scores of “overall appreciation” were attributed to control rosé wine, while significantly higher scores for “color intensity” descriptor were attributed to all rosé wines matured in contact with wood chips. For the majority of phenolic parameters and individual phenolic compounds quantified, a clear and specific influence of the use of oak and cherry wood chips was not detected, except for (+)-catechin, where the rosé wines produced in contact with cherry chips showed the highest values. This study provides relevant information for winemakers about the impact of the use of wood chips on rosé wine quality.

Effects of smoke flavoring using different wood chips and barbecuing on the formation of polycyclic aromatic hydrocarbons and heterocyclic aromatic amines in salmon fillets.

Herein, the concentrations of food toxicants, polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatic amines (HAAs), in salmon fillets smoke flavored with different smoking wood chips (oak, apple, bourbon soaked oak, cherry and hickory) and barbecuing were determined. Benzo[a]anthracene (up to 0.24 ng/g) and chrysene (0.22 ng/g) were determined in the raw salmon fillets. While ∑PAH8 (benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, benzo[g,h,i]perylene, indeno[1,2,3-cd]pyrene) in the raw samples ranged between 0.44 and 0.46 ng/g, smoke flavoring increased the amount of ∑PAH8 and the amount varied between 0.47 and 0.73 ng/g. Salmon smoked flavored with bourbon soaked oak, cherry and hickory wood chips and barbecued showed significantly (P <0.05) lower contents of ∑PAH4 (benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[a]pyrene) and ∑PAH8 compared to non-smoke flavored barbecued samples. Additionally, smoke flavoring with apple, bourbon soaked oak, and cherry wood chips significantly (P <0.05) reduced the total HAA contents in barbecued salmon. A remarkable result was that the bourbon-soaked oak and cherry wood chips had inhibitory effects on both PAH and HAA contents. In sum, barbecued non-smoke flavored and smoke flavored salmon with different wood chips could be considered safe from the perspective of the detected amounts of PAHs and HAAs in salmon fillets.

Denitrifying Woodchip Bioreactor Leachate Tannic Acid and True Color: Lab and Field Studies

HighlightsOak leached more tannic acid, true color, and chemical oxygen demand (COD) than ash and mixed hardwood chips.The factors became similar (tannic acid, COD) or below stream levels (true color) after flushing.Eleven site-years of field bioreactor data showed decreasing tannic acid and true color over time.Post-startup tannic acid was lower in bioreactor outflow than in area streams.True color did not appear to be a reliable indicator of leachate tannic acid at low concentrations.Abstract. Woodchips have been a preferred denitrifying bioreactor medium to date, but concerns about potential harmful effects of tannins in the leachate have precluded the use of oak chips in many installations. A study was conducted to compare the suitability of oak (genus Quercus) woodchips as a denitrifying bioreactor medium relative to other types of woodchips, both in lab leachate tests and in the context of observed bioreactor leaching in the field. Assessment measures included the content of tannic acid and other compounds in the leachate, as well as leachate color, which can often be high during startup. An 84-day leaching test using rectangular bioreactor cells filled with either oak (Quercus rubra), ash (Fraxinus spp. L.), or a generic hardwood blend showed that oak initially leached higher concentrations of tannic acid, true color, and chemical oxygen demand (COD) than the other two media. The significant differences in leached concentrations among the three wood types were eliminated after a finite leaching period. Tannic acid and true color in 11 site-years of field bioreactor outflow data generally decreased over time, except following a dry period when one of the bioreactors received no drainage inflow for more than two months. The lab and field results indicated the capability of woodchip bioreactors to flush at least these two analytes to ambient stream levels. True color did not appear to be the best parameter for estimating the tannin content of woodchip leachate due to discrepancies at low concentrations. Mass normalized tannic acid leaching ranged from 0.03 to approximately 40 mg tannic acid g-1 woodchip across the lab and field assessments. Oak initially leached more tannic acid, color, and COD than the other wood types, but the eventual similarity among the wood types after flushing with a sufficient number of pore volumes meant that any potentially negative environmental impacts would likely be limited to the startup period or possibly after dry periods. Oak initially eluted higher mean total nitrogen (TN) concentrations than the other wood types, but the treatments were not significantly different by day 3, indicating that biological N removal was not significantly inhibited, even with high concentrations of tannic acid. Keywords: Chemical oxygen demand, Oak, Tannin, Water quality, Wood leachate.