Stéphane Godbout

Soil biochar amendment as a climate change mitigation tool: Key parameters and mechanisms involved

Biochar, a solid porous material obtained from the carbonization of biomass under low or no oxygen conditions, has been proposed as a climate change mitigation tool because it is expected to sequester carbon (C) for centuries and to reduce greenhouse gas (GHG) emissions from soils. This review aimed to identify key biochar properties and production parameters that have an effect on these specific applications of the biochar. Moreover, mechanisms involved in interactions between biochar and soils were highlighted. Following a compilation and comparison of the characteristics of 76 biochars from 40 research studies, biochars with a lower N content, and consequently a higher C/N ratio (>30), were found to be more suitable for mitigation of N2O emissions from soils. Moreover, biochars produced at a higher pyrolysis temperature, and with O/C ratio <0.2, H/Corg ratio <0.4 and volatile matter below 80% may have high C sequestration potential. Based on these observations, biochar production and application to the field can be used as a tool to mitigate climate change. However, it is important to determine the pyrolysis conditions and feedstock needed to produce a biochar with the desired properties for a specific application. More research studies are needed to identify the exact mechanisms involved following biochar amendment to soil.

A critical review of emission standards and regulations regarding biomass combustion in small scale units (<3 MW).

Wood and agricultural crop residues are abundant, renewable and relatively low cost biomasses. Their combustion can replace fossil fuels in several applications. A major concern with biomass combustion is the emission of particulate matter (PM) in the atmosphere. The World Health Organization (WHO) has developed ambient air quality guidelines, notably maximum average annual levels of 20 μg/m(3) for PM10 (particulate matter<10 μm). Combustion standards generally assess total PM at the chimney stack, with variable levels depending on local legislation, industrial activity, population density, etc. (e.g. 100-200mg/m(3) in Massachusetts, 150 mg/m(3) in Québec, and 600 mg/m(3) in New York). Some areas mandate relatively low PM levels from boilers (50mg/m(3) in Europe, 20mg/m(3) in Germany starting in 2015). The availability of conditioned and relatively dry biomass, along with PM removal technologies (e.g. cyclones, scrubbers, precipitators, and baghouse filters), will become important requirements for future biomass combustion.

Comparison of the gaseous and particulate matter emissions from the combustion of agricultural and forest biomasses.

The aim of this study was to compare gaseous and particulate matter (PM) emissions from the combustion of agricultural (switchgrass, fast-growing willow and the dried solid fraction of pig manure) and forest (wood mixture of Black Spruce and Jack Pine) biomasses in a small-scale unit (17.58kW). Concentrations of CO2, CO, CH4, NO2, NH3, N2O, SO2, HCl, and H2O were measured by Fourier transform infrared spectroscopy and converted into emission rates. Opacity was also evaluated and particulates were sampled. Results showed significantly higher emissions of SO2, NO2 and PM with the combustion of agricultural biomass compared to the forest biomass. However, further studies should be carried out so regulations can be adapted in order to permit the combustion of agricultural biomass in small-scale combustion units.

Predicting gaseous emissions from small-scale combustion of agricultural biomass fuels.

A prediction model of gaseous emissions (CO, CO2, NOx, SO2 and HCl) from small-scale combustion of agricultural biomass fuels was developed in order to rapidly assess their potential to be burned in accordance to current environmental threshold values. The model was established based on calculation of thermodynamic equilibrium of reactive multicomponent systems using Gibbs free energy minimization. Since this method has been widely used to estimate the composition of the syngas from wood gasification, the model was first validated by comparing its prediction results with those of similar models from the literature. The model was then used to evaluate the main gas emissions from the combustion of four dedicated energy crops (short-rotation willow, reed canary grass, switchgrass and miscanthus) previously burned in a 29-kW boiler. The prediction values revealed good agreement with the experimental results. The model was particularly effective in estimating the influence of harvest season on SO2 emissions.

Value-added performance of processed cardboard and farm breeding compost by pyrolysis

This study aims to underline the huge potential in Canada of adding value to cardboard and compost as a renewable fuel with a low ecological footprint. The slow pyrolysis process of lined cardboard and compost blend was investigated. Thermal behavior was investigated by thermogravimetric analysis coupled with mass spectrometry (TGA-MS). The thermal profiles are presented in the form of TGA/DTG curves. With a constant heating rate of 10 °C/min, two parameters, temperature and time were varied. Cardboard decomposition occurred mostly between 203 °C and 436 °C, where 77% of the sample weight was decomposed. Compost blend decomposition occurred mostly between 209 °C and 373 °C, with 23% of weight. The principal gaseous products that evolved during the pyrolysis were H2O, CO and CO2. As a result, slow pyrolysis led to the formation of biochar. High yield of biochar from cardboard was found at 250 °C for a duration of 60 min (87.5%) while the biochar yield from the compost blend was maintained constant at about 31%. Finally, kinetic parameters and a statistical analysis for the pyrolysis process of the cardboard and compost samples have been investigated. Both materials showed a favorable thermochemical behavior. However, unlike cardboard, compost pyrolysis does not seem a promising process because of the low superior calorific and biochar values.

Greenhouse Gas Emissions from Three Cage Layer Housing Systems

Simple Summary Greenhouse gas (GHG) emissions were measured from three different cage layer housing systems. A comparative study was conducted to identify the housing system with the least impact on the environment. The results showed that liquid manure from deep-pit housing systems produces greater emissions of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) than natural and forced dried manure from belt housing systems. The influencing factors appeared to be the manure removal frequency and the dry matter content of the manure. Abstract Agriculture accounts for 10 to 12% of the World’s total greenhouse gas (GHG) emissions. Manure management alone is responsible for 13% of GHG emissions from the agricultural sector. During the last decade, Québec’s egg production systems have shifted from deep-pit housing systems to manure belt housing systems. The objective of this study was to measure and compare carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions from three different cage layer housing systems: a deep liquid manure pit and a manure belt with natural or forced air drying. Deep liquid manure pit housing systems consist of “A” frame layer cages located over a closed pit containing the hens’ droppings to which water is added to facilitate removal by pumping. Manure belt techniques imply that manure drops on a belt beneath each row of battery cages where it is either dried naturally or by forced air until it is removed. The experiment was replicated with 360 hens reared into twelve independent bench-scale rooms during eight weeks (19–27 weeks of age). The natural and forced air manure belt systems reduced CO2 (28.2 and 28.7 kg yr−1 hen−1, respectively), CH4 (25.3 and 27.7 g yr−1 hen−1, respectively) and N2O (2.60 and 2.48 g yr−1 hen−1, respectively) emissions by about 21, 16 and 9% in comparison with the deep-pit technique (36.0 kg CO2 yr−1 hen−1, 31.6 g CH4 yr−1 hen−1 and 2.78 g N2O yr−1 hen−1). The shift to manure belt systems needs to be encouraged since this housing system significantly decreases the production of GHG.

GAS AND ODOR EMISSIONS FROM SWINE BUILDING MATERIALS

Gas and odor emissions produced by twelve different materials commonly used in typical swine buildings were measured using a method based on ASTM standard D-5116. After being submerged for 72 h in swine manure, material samples were thereafter randomly introduced into twelve monitoring testing chambers. The stainless steel testing chambers allowed precise control of the interior temperature, relative humidity, air speed, and airflow. Samples remained in the chambers for a 24 h desorption period. During this period, gas emissions (NH3, CH4, N2O, and CO2) were measured continuously. At the end of the desorption period, the air in each testing chamber was sampled in 80 L Tedlar bags for the determination of the odor concentration with a dynamic olfactometer using a human panel. Olfactometry results showed that plastics, like Plastisol and HDPE, and plywood were the most odorous materials, followed by concrete, PVC, galvanized steel, and cast iron. Over the period of desorption, NH3 emissions were relatively constant. The highest NH3 emissions were produced by the 30 MPa normal concrete, which reached a maximum of about 175 mg m-2 h-1. CO2 emissions were similar for all materials and increased linearly with time.

Greenhouse Gas and Odor Emissions from Liquid Swine Manure Storage and Manure Treatment Facilities in Quebec

Greenhouse gas (GHG) and odor emissions were measured over a two-year period from a swine manure storage tank and from two swine manure treatment facilities (an aerobic-anoxic and a biofilter manure treatment system). Floating open chambers were used to collect air samples on top of the stored manure. GHG concentrations were either measured continuously, by gas chromatography, or determined from air samples collected using syringes and stored in evacuated glass containers. Air bag samples were collected and odor concentrations (in OU m-3) were measured using a dynamic dilution olfactometer. Odor intensities (in ppb eq of 1-butanol) were measured on site using a suprathreshold dynamic dilution olfactometer. Total GHG emissions (including CO2) from the farm under liquid manure management (manure tank and land application) were equal to 5.3 kg CO2 eq year-1 kgpigs -1. From the aerobic-anoxic treatment system and the biofilter treatment system, total GHG emissions were equal to 1.9 and 3.5 kg CO2 eq year-1 kgpigs -1, respectively. Odor emissions from the manure tank were 12 OU s-1 m-2. From the aerobic-anoxic treatment system and the biofilter treatment system, odor emissions were 1.5 OU s-1 m-3 and 6.7 OU s-1 m-3, respectively.

Alternatives to antibiotics in poultry feed: molecular perspectives.

Abstract The discovery of the growth promoting property of antibiotics led to their use as antibiotic feed additives (AFAs) in animal feed at sub-therapeutic doses. Although this has been beneficial for animal health and productivity, it has been, essentially, a double-edged sword. The continued and non-judicious use of AFAs has led to the selection and dissemination of antibiotic-resistant strains of poultry pathogens such as Salmonella, Campylobacter and Escherichia coli. The rapid spread of drug-resistant pathogens as well as emergence of antibiotic-related environmental pollutants is of global concern. Hence, the identification and development of new and effective alternatives to antibiotics that do not hinder productivity is imperative. For this, it is essential to understand not only the molecular basis of development of resistance to AFAs but also the mechanisms of action of AFA alternatives and how they differ from AFAs. This review provides a molecular perspective on the alternatives to antibiotics that have been proposed till date and their current trends, as well as novel approaches such as development of improved delivery systems.

Biotrickling filter for the treatment of swine exhaust air.

The piggery industry is important both worldwide and in Canada, but swine production sites can emit substantial amounts of aerial contaminants. Biological treatment systems, such as biotrickling filters (BTF), have the potential to treat these emissions which are generally characterised by low concentrations and very high flow rates. The main objective of this study was to test the effect of certain operating parameters on the performance of BTFs treating swine exhaust air.