Thesis Format
Alternative Format
Degree
Doctor of Philosophy
Program
Chemical and Biochemical Engineering
Supervisor
Berruti, Franco
2nd Supervisor
Klinghoffer, Naomi
Co-Supervisor
Abstract
This thesis aimed to develop and validate the Carbon Control Technology (CCT®), a novel, patented process for converting waste agricultural residues into carbon-based controlled-release fertilizers (CBCRFs) through chemical carbonization followed by nutrient impregnation. The process involved treating lignocellulosic biomass with 93% sulfuric acid to produce a stable carbon matrix, subsequently neutralized with anhydrous ammonia to incorporate nitrogen. In partnership with Sulvaris Inc. and the Institute for Chemicals and Fuels from Alternative Resources (ICFAR), pilot-scale reactors were designed, improved, and operated, producing over 600 kg of CCT® material for field trials. These products demonstrated nitrogen contents of 15–17% and sulfur levels of 18–20%. The second phase of this work investigated how lignocellulosic composition influenced CBCRF properties. Chars derived from pine, spruce, coconut, and switchgrass were characterized using elemental analysis, FTIR, TGA/DTG, BET, SEM-EDX, and XPS. Switchgrass chars exhibited the highest porosity (423.97 m2/g) and surface oxygenation (COOH up to 13.51%), promoting nutrient loading but associated with lower thermal stability. Coconut chars, with high aromaticity (C-C/C=C 48.17%), offered greater structural durability but fewer reactive sites for nutrient binding. Pine and spruce chars provided a balance, with moderate porosity and oxygen functionality supporting both nutrient retention and controlled-release potential. Across all feedstocks, nutrient impregnation was successful: nitrogen contents of up to 4.59% (spruce) and sulfur up to 2.11% (coconut) were retained post-washing, with XPS confirming incorporation as quaternary nitrogen (NR3+) and sulfonic (SO3-) groups. SEM-EDX showed uniform distribution of nitrogen and sulfur, while TGA/DTG analysis revealed that washed CBCRFs exhibited more gradual degradation profiles, consistent with chemical stabilization rather than mere physical adsorption. Collectively, these results confirm that the CCT® process effectively carbonizes diverse lignocellulosic residues and produces nutrient-functionalized matrices suitable for use as slow-release fertilizers, with structural and chemical traits tunable via feedstock selection and process conditions.
Summary for Lay Audience
This project focused on creating a new type of environmentally friendly fertilizer from plant-based waste materials like wood chips, coconut husks, and grasses. The goal was to develop a process called Carbon Control Technology (CCT) that transforms agricultural residues into high-performing, slow-release fertilizers that are better for both crops and the planet.
Working with Sulvaris Inc., this study explores a new approach to making carbon-based slow-release fertilizers (CBCRFs) that are environmentally friendly through the use of waste agricultural materials (like wood, coconut husk, and grasses) which are abundant and renewable. Instead of the typical fertilizer production methods which emit tremendous quantities of greenhouse gases, this study uses a chemical process which is much less environmentally harmful. This process involves breaking down the plant material with strong acids and then adding important nutrients like nitrogen, sulfur, and phosphorus with the goal to make fertilizers that release their nutrients slowly, matching the needs of plants better, and reducing runoff which leads to harmful environmental occurrences like eutrophication and dead zones. Early results from farms showed that this fertilizer improved crop yields.
Overall, this work showed that a wide range of plant-based wastes can be turned into valuable, sustainable fertilizers. It offers a promising way to reduce agricultural pollution while making better use of organic waste.
Recommended Citation
Horvers, Stephanos, "Development of Carbon-Based, Controlled-Release Soil Ameliorants Through Chemical Pathways" (2025). Electronic Thesis and Dissertation Repository. 10884.
https://ir.lib.uwo.ca/etd/10884
Creative Commons License
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