skip to main content


Title: Bio‐Carbon as a Means of Carbon Management in Roads
Abstract

This paper introduces biocarbon, referred to as biochar, as a novel eco‐friendly and cost‐effective additive to increase interactions among bitumen components while facilitating carbon management in roadway infrastructures. It is hypothesized that functional groups on biochar surfaces enhance interactions between biochar and bitumen constituents. This in turn enhances mechanical properties and durability of asphalt pavements. This study uses biochars derived from six different types of woody biomass and one type of algae, and polyethylene terephthalate granules as a carrier to introduce biochar to bitumen. Quantum‐based molecular modeling and noncovalent interaction analysis show that algal biochar interacts more effectively with bitumen components. The enhanced interaction of algal biochar is attributed to its surface functional groups including reactive nitrogen‐ and oxygen‐carrying functional groups. The rheological characterization of bitumen doped with different biochars confirms that the lowest separation index occurs for bitumen containing algal biochar, which also exhibits the highest percent of elastic recovery and resistance to permanent deformation. The study suggests that asphalt pavement durability can be enhanced by selection of the proper biochar to increase intermolecular interactions. Promising results for the algae biochar promote its use in carbon management for roadway infrastructure by sequestering CO2from air through photosynthesis of algae biomass.

 
more » « less
NSF-PAR ID:
10419252
Author(s) / Creator(s):
 ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Advanced Sustainable Systems
Volume:
7
Issue:
6
ISSN:
2366-7486
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    Producer–decomposer interactions within aquatic biofilms can range from mutualistic associations to competition depending on available resources. The outcomes of such interactions have implications for biogeochemical cycling and, as such, may be especially important in northern peatlands, which are a global carbon sink and are expected to experience changes in resource availability with climate change. The purpose of this study was to evaluate the effects of nutrients and organic carbon on the relative proportion of primary producers (microalgae) and heterotrophic decomposers (bacteria and fungi) during aquatic biofilm development in a boreal peatland. Given that decomposers are often better competitors for nutrients than primary producers in aquatic ecosystems, we predicted that labile carbon subsidies would shift the biofilm composition towards heterotrophy owing to the ability of decomposers to outcompete primary producers for available nutrients in the absence of carbon limitation.

    We manipulated nutrients (nitrate and phosphate) and organic carbon (glucose) in a full factorial design using nutrient‐diffusing substrates in an Alaskan fen.

    Heterotrophic bacteria were limited by organic carbon and algae were limited by inorganic nutrients. However, the outcomes of competitive interactions depended on background nutrient levels. Heterotrophic bacteria were able to outcompete algae for available nutrients when organic carbon was elevated and nutrient levels remained low, but not when organic carbon and nutrients were both elevated through enrichment.

    Fungal biomass was significantly lower in the presence of glucose alone, possibly owing to antagonistic interactions with heterotrophic bacteria. In contrast to bacteria, fungi were stimulated along with algae following nutrient enrichment.

    The decoupling of algae and heterotrophic bacteria in the presence of glucose alone shifted the biofilm trophic status towards heterotrophy. This effect was overturned when nutrients were enriched along with glucose, owing to a subsequent increase in algal biomass in the absence of nutrient limitation.

    By measuring individual components of the biofilm and obtaining data on the trophic status, we have begun to establish a link between resource availability and biofilm formation in northern peatlands. Our results show that labile carbon subsidies from outside sources have the potential to disrupt microbial coupling and shift the metabolic balance in favour of heterotrophy. The extent to which this occurs in the future will probably depend on the timing and composition of bioavailable nutrients delivered to surface waters with environmental change (e.g. permafrost thaw).

     
    more » « less
  2. Highlights

    Non-carbonate components of BG11 media impact TIC calculation on average 4.00 mg/L at high pH.

    BG11 media non-carbonate alkalinity (NCA) varies with pH: NCA (meq/L) = 0.0393×e0.2075×pH+ (2.086×10-9)e1.860×pH.

    Monod kinetic constants with CO2, HCO3-, and CO32-as inorganic carbon sources are improved from a previous report.

    Kinetic constants continue to be the only known reports considering multiple inorganic carbon sources.

    Algal stoichiometric reactions are developed that account for variation in cell content and carbon source.

    Abstract.Due to increasing atmospheric CO2, algal growth systems at high pH are of interest to support enhanced diffusion and carbon capture. Given the interactions between algal growth, pH, and alkalinity, data from Watson and Drapcho (2016) were re-examined to determine the impact of the non-carbonate constituents in BG11 media on estimates of Monod kinetic parameters, biomass yield, and cell stoichiometry. Based on a computational method, non-carbonate alkalinity (NCA) in BG11 media varies with pH according to: NCA (meq/L) = 0.0393×e0.2075×pH + (2.086×10-9)e1.860×pH (R2 = 0.999) over the pH range of 10.3 – 11.5. Updated maximum specific growth rates were determined to be 0.060, 0.057, and 0.051 hr-1 for CO2, HCO3, and CO3, respectively. Generalizable stoichiometric algal growth equations that consider variable nutrient ratios and multiple inorganic carbon species were developed. Improved kinetic and stoichiometric parameters will serve as the foundation for a dynamic mathematical model to support the design of high pH algal carbon capture systems. Keywords: Algae, Alkalinity, Carbon Abatement, Carbon Capture, Kinetics, Stoichiometry, Total Inorganic Carbon.

     
    more » « less
  3. Abstract

    The current paradigm in peatland ecology is that the organic matter inputs from plant photosynthesis (e.g. moss litter) exceed that of decomposition, tipping the metabolic balance in favour of carbon (C) storage. Here, we investigated an alternative hypothesis, whereby exudates released by microalgae can actually accelerate C losses from the surface waters of northern peatlands by stimulating dissolved organic C (DOC) decomposition in a warmer environment expected with climate change. To test this hypothesis, we evaluated the biodegradability of fenDOCin a factorial design with and without algalDOCin both ambient (15°C) and elevated (20°C) water temperatures during a laboratory bioassay.

    WhenDOCsources were evaluated separately, decomposition rates were higher in treatments with algalDOConly than with fenDOConly, indicating that the quality of the organic matter influenced degradability. A mixture of substrates (½ algalDOC + ½ fenDOC) exceeded the expected level of biodegradation (i.e. the average of the individual substrate responses) by as much as 10%, and the magnitude of this effect increased to more than 15% with warming.

    Specific ultraviolet absorbance at 254 nm (SUVA254), a proxy for aromatic content, was also significantly higher (i.e. more humic) in the mixture treatment than expected from SUVA254values in single substrate treatments.

    Accelerated decomposition in the presence of algalDOCwas coupled with an increase in bacterial biomass, demonstrating that enhanced metabolism was associated with a more abundant microbial community.

    These results present an alternative energy pathway for heterotrophic consumers to breakdown organic matter in northern peatlands. Since decomposition in northern peatlands is often limited by the availability of labile organic matter, this mechanism could become increasingly important as a pathway for decomposition in the surface waters of northern peatlands where algae are expected to be more abundant in conditions associated with ongoing climate change.

     
    more » « less
  4. Abstract Background

    Woody biomass has been considered as a promising feedstock for biofuel production via thermochemical conversion technologies such as fast pyrolysis. Extensive Life Cycle Assessment studies have been completed to evaluate the carbon intensity of woody biomass-derived biofuels via fast pyrolysis. However, most studies assumed that woody biomass such as forest residues is a carbon–neutral feedstock like annual crops, despite a distinctive timeframe it takes to grow woody biomass. Besides, few studies have investigated the impacts of forest dynamics and the temporal effects of carbon on the overall carbon intensity of woody-derived biofuels. This study addressed such gaps by developing a life-cycle carbon analysis framework integrating dynamic modeling for forest and biorefinery systems with a time-based discounted Global Warming Potential (GWP) method developed in this work. The framework analyzed dynamic carbon and energy flows of a supply chain for biofuel production from pine residues via fast pyrolysis.

    Results

    The mean carbon intensity of biofuel given by Monte Carlo simulation across three pine growth cases ranges from 40.8–41.2 g CO2e MJ−1(static method) to 51.0–65.2 g CO2e MJ−1(using the time-based discounted GWP method) when combusting biochar for energy recovery. If biochar is utilized as soil amendment, the carbon intensity reduces to 19.0–19.7 g CO2e MJ−1(static method) and 29.6–43.4 g CO2e MJ−1in the time-based method. Forest growth and yields (controlled by forest management strategies) show more significant impacts on biofuel carbon intensity when the temporal effect of carbon is taken into consideration. Variation in forest operations and management (e.g., energy consumption of thinning and harvesting), on the other hand, has little impact on the biofuel carbon intensity.

    Conclusions

    The carbon temporal effect, particularly the time lag of carbon sequestration during pine growth, has direct impacts on the carbon intensity of biofuels produced from pine residues from a stand-level pine growth and management point of view. The carbon implications are also significantly impacted by the assumptions of biochar end-of-life cases and forest management strategies.

     
    more » « less
  5. Abstract Biochar is a solid by-product of thermochemical conversion of biomass to bio-oil and syngas. It has a carbonaceous skeleton, a small amount of heteroatom functional groups, mineral matter, and water. Biochar’s unique physicochemical structures lead to many valuable properties of important technological applications, including its sorption capacity. Indeed, biochar’s wide range of applications include carbon sequestration, reduction in greenhouse gas emissions, waste management, renewable energy generation, soil amendment, and environmental remediation. Aside from these applications, new scientific insights and technological concepts have continued to emerge in the last decade. Consequently, a systematic update of current knowledge regarding the complex nature of biochar, the scientific and technological impacts, and operational costs of different activation strategies are highly desirable for transforming biochar applications into industrial scales. This communication presents a comprehensive review of physical activation/modification strategies and their effects on the physicochemical properties of biochar and its applications in environment-related fields. Physical activation applied to the activation of biochar is discussed under three different categories: I) gaseous modification by steam, carbon dioxide, air, or ozone; II) thermal modification by conventional heating and microwave irradiation; and III) recently developed modification methods using ultrasound waves, plasma, and electrochemical methods. The activation results are discussed in terms of different physicochemical properties of biochar, such as surface area; micropore, mesopore, and total pore volume; surface functionality; burn-off; ash content; organic compound content; polarity; and aromaticity index. Due to the rapid increase in the application of biochar as adsorbents, the synergistic and antagonistic effects of activation processes on the desired application are also covered. 
    more » « less