Progress 09/01/18 to 08/31/19
Target Audience:Audiences at technical conferences, including the International Biochar Initative in Ft. Collins, CO. The technical conference audiences include USDA technical and administrative representatives, researchers from universities and non-profits, company R&D and business development personnel, farmers and agricultural trade and commodity groups. Changes/Problems:
What opportunities for training and professional development has the project provided?This project provides graduate and undergraduate students an opportunity to work in the area of chemical, agricultural and biological engineering. Graduate students are expected to conduct experiments and present results in written reports and oral presentation. They receive training on experimental design, data collection and analysis, as well as environmental monitoring. Graduate students and post docs will also have opportunities to prepare manuscripts for technical journals and present at technical conferences attended by universities, federal agencies including the USDA, and companies. Undergraduate students were involved in data collection and utilization and received training on measurement methods, soil analysis, and water analysis. An international student (Zhanibek Meiirkhanuly) was trained to work in this project, graduated and received his M.S. degree Environmental Science at Iowa State University in August 2019. How have the results been disseminated to communities of interest?Objective 1. An oral presentation has been presented at the Biochar & Bioenergy annual conference in 2019. Another oral presentation will be presented at the American Chemical Society Spring meeting in 2020. A scientific journal publication is under preparation for submission in early 2020. Objective 2. A manuscript was published in Water. Additional manuscripts focused on the effect of biochar addition on pH in the air-manure interface is in preparation. Objective 3. A manuscript is being completed and is nearly ready for submission. Objective 4. A manuscript is in preparation for Transactions of the ASABE. Objective 5. A scientific journal publication is under preparation for submission in 2019. A poster and oral presentation are planned for delivery in 2020. What do you plan to do during the next reporting period to accomplish the goals?Objective 1. Efficacy of the FeSO4 impregnated biochar towards phosphate recycling using both agricultural and industrial effluents by performing benchtop leaching trials. Objective 2. Year 2 pilot-scale evaluation of the effects of HAP biochar dose and time on odor, NH3, H2S, key odorous VOCs responsible for downwind swine barn odor, and GHGs (CO2, CH4, N2O) on emissions from simulated swine manure storage treated with a surficial application of biochar. Objective 3. AD of the fibrous feedstock materials (grasses): The fescue grass, prairie grass, and mixtures of manure and these grasses will be used as feedstock for AD. A CSTR will be used for digesting grasses, while a plug flow reactor (PFR) will be used to digest the manure/grass mixtures due to the difficulty of processing these heterogeneous mixtures in CSTRs. AD will be performed in both liquid (>85% moisture content) and solid (<85% moisture content) phases to accommodate the nature of grassy biomass. In addition to mesophilic AD, we will also use a temperature-phase method, i.e., thermophilic stage first to hydrolyze the recalcitrant fiber and produce volatile fatty acid, followed by the mesophilic stage for the CH4 production, to treat the materials with efficient raw material degradation and process stability. Objective 4. A follow up experiment is being conducted to evaluate the impact of biochar addition rate to both swine manure and poultry manure. We developed and refined our methodology for composting analysis and plan to evaluate how adding biochar to compost impacts both compost processes and ammonia loss of bedded pack cattle manure and herbaceous material separated from anaerobic digesters. Objective 5. Process models will be updated with experimental data gathered from the project. Economic assumptions will be updated when the model is modified to account for new performance metrics. Process design will be optimized to minimize costs. Lifecycle analysis results will be updated when the model is modified to account for new performance metrics. Process design will be optimized to minimize environmental impacts.
What was accomplished under these goals?
Objective 1. Biochar Production Autothermal (air-blown) pyrolysis of ferrous sulfate treated corn stover was carried out to produce FeSO4 impregnated biochar. Autothermal pyrolysis of untreated corn stover was conducted to produce control biochar (CS-control). Characteristics of these biochars are shown in Table 1. Phosphate sorption tests in solution with 0, 100, 400, 1000 and 4000 mg L-1 phosphate concentration at 48 hours with solid loading of 5 g/L and pH 7.5-8.2 were conducted. Phosphate sorption capacity of CS-FeSO4 biochar was 88.7 mg of phosphate per g biochar. Phosphate sorption capacity of CS-control biochar was only 59.8 mg of phosphate per g biochar. Desorption isotherms with three washings of water and Mehlich-III solution were done to test release of phosphate from the biochar. Desorption rates for CS-control biochar in water and Mehlich-III solution were 52.28% and 69.48%, respectively. Desorption rates for ferrous sulfate treated corn stover biochar were 15.15% and 26.19% in water and Mehlich-III solution, respectively. The combination of autothermal pyrolysis and ferrous sulfate treatment dramatically increases phosphate sorption capacity, and dramatically decreases desorption rates. Table 1: Biochar properties Figure 1: Phosphate sorption and desorption data of (a) biochar from untreated corn stover and (b) biochar from ferrous sulfate treated corn stover. Blue - water desorption; Gray - Mehlich-III desorption. Numbers in the dark portion of each bar represent the % phosphate desorbed. The number below each bar (PO43- aq mg L-1) is the phospate concentration remaining in the aqueous phase. The number above each bar (PO43- ads mg g-1) indicates indicates concentration of adsorbed phosphate. The four pairs of bars in each chart from L-R are results from 0, 100, 400, 1000 and 4000 mg L-1 phosphate-concentrated solutions. Objective 2. Biochar amended anaerobic digestion Anaerobic digestions (AD) experiments were conducted using municipal sludge. A control group (A0) without biochar addition and groups amended with biochar from untreated corn stover (A1), and biochar from sulfuric acid treated corn stover (A2) at three different dosages (L, M, and H) were investigated. The three dosages of biochar from low to high included 3.6g/g TSsludge (L), 7.2 g/g TSsludge (M) and 15 g/g TSsludge (H). Each digester contained inoculum (0.44g TS), sludge (0.36g TS), biochar (varies) and deionized (DI) water to total 80mL. Each condition was conducted in duplicate. Fig. 2 shows the time course of cumulative biogas production, cumulative methane production and daily methane content. Untreated corn stover biochar addition increased cumulative biogas and methane production proportional to biochar dosages. Sulfuric acid treated corn stover biochar increased the biogas production (Fig. 2B) but only significantly (p<0.05) with high dosage (A2-H). All of the three dosages resulted in significant higher methane production than that of the control group A0 (p<0.05). Contrary to the trend of biogas production in Fig. 2B, addition of sulfuric acid treated corn stover biochar decreased the methane production. Figure 2. Time-course profiles of AD experiments. Cumulative biogas production with: (A) untreated corn stover biochar; (B) sulfuric acid treated corn stover biochar. Cumulative methane production with: (C) untreated corn stover biochar; (D) sulfuric acid treated corn stover biochar. Methane content with: (E) untreated corn stover biochar; (F) sulfuric acid treated corn stover biochar. Objective 3. Livestock odor control Experiments to study biochar pH impact on the liquid-air interface were completed. Small doses of biochar were surficially-applied on water and swine manure to study the temporal and spatial (with depth) changes that regulate emissions of pH-sensitive odorous compounds from liquid to air. The impact of HAP corn stover biochar (pH 9.2) was compared with red oak (RO) biochar (pH 7.5). Both experiments showed OH- ions from biochar gradual movement from the surface into the water and manure. Both experiments support the hypothesis that biochar pH can be used to control the odorous compound emissions by buffering the H+/OH- ion concentrations. Table 2. Physicochemical properties of two manures sourced from a lagoon and pit used in this experiment. Lab-scale experiments were completed to evaluate the impact of HAP and RO biochar surficial application on mitigation of NH3, H2S, odorous VOCs and GHGs (CO2, CH4, N2O) emissions from swine manure. Both biochars showed the highest reduction of NH3 emissions on the day after application. Surficial biochar addition to manure reduced odorous VOCs emission up to 90% depending on the type of manure. Biochar application reduced the CH4 emission for the first two weeks after the surficial application then enhanced the CH4 emissions compared to untreated manure. High ash content and porosity is likely reducing the biochar floatability and therefore its ability to control the odorous compounds and their emissions in the long term. Green font represents significant reduction vs. control. Red font represents significant increase vs. control. Table 3. Efficacy of surficially-applied HAP biochar in mitigating NH3 emissions (mg/h/m2) from swine manure (lab-scale trials). Table 4. Efficacy of surficially-applied HAP biochar in mitigating H2S emission emissions (mg/h/m2) from swine manure (lab-scale trials). Table 5. Efficacy of HAP biochar in mitigating CH4 emission flux (mg/h/m2) from swine manure (lab-scale trials). Table 6. Efficacy of HAP biochar in mitigating odor emission (OUe.m-3) from swine manure Table 7. Efficacy of HAP biochar in mitigating odorous VOC emissions from manure over three lab-scale trials. Objective 4. Biochar amended digestate and manure composting The relationship between biochar and liquid swine manure application and its effect on total nitrogen loss was investigated. For eight weeks, soil columns were leached to determine total NO3-N loss of soil alone, biochar amended soil, swine manure, and a combination of biochar and swine manure. In this study, it was determined that swine manure increased the amount of nitrogen lost from the soil, the addition of biochar to swine manure treated soil decreased total nitrate loss. It is suggested that biochar has the ability to increase water and nutrient retention, reducing the risk of nitrogen loss. Figure 3: Cumulative Nitrate Loss by Treatment; Shared letters show no significant difference. Figure 4: Progressive Nitrate Loss by Treatment; Shared letters show no significant difference. Objective 5. Economic analysis and life cycle assessment Aspen PlusTM process models have been developed simulating gasoline and power production via pyrolysis-hydroprocessing-anaerobic digestion (Scenario I), and ethanol and power production via pyrolysis-fermentation-anaerobic digestion (Scenario II). Both scenarios assume conversion of 2000 metric tonnes per day of corn stover and 430 dry tonnes per day of manure to liquid transportation fuels, electricity, phenolic compounds, and biochar products. Total capital costs were estimated at $642 and $719 million for the gasoline and ethanol production scenarios, respectively. Preliminary minimum fuel selling prices for scenarios I and II were $2.71 per gallon and $2.31 per gallon (or $3.46 per gallons of gasoline equivalent). Corn stover and return on investment (ROI) contributed the most towards the MFSP in both scenarios. Preliminary life cycle analysis results showed negative greenhouse gas emissions for both scenarios. Life cycle emissions were estimated at -9.6 gm CO2,eqv. /MJ for scenario I and -80 gm CO2,eqv. /MJ for scenario II. Figure5. Cornstoverfast pyrolysis to gasoline or ethanol and manure anaerobic digestion to power Table 8:Comparison of gasoline and ethanol production scenario costs, fuel yield, minimum fuel-selling price, and greenhouse gas emissions GGE: gallons of gasoline equivalent
Conference Papers and Presentations
Bakshi, S.; Gable, P.; Brown, R. C., 2018. Phosphate sorption onto modified biochar surface. Biochar & Bioenergy, International Biochar Initiative, Fort Collins, CO, June 30-July 3, 2019 (Oral presentation).
Meiirkhanuly, Z., J.A. Koziel, C. Banik, A. Bialowiec, R. Brown. 2019, The-proof-of-concept of biochar floating cover influence on water pH. Water, 11(9), 1802; doi: 10.3390/w11091802.