Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Engineering Science

Program

Chemical and Biochemical Engineering

Supervisor

Briens, Cedric

2nd Supervisor

Briens, Lauren

Co-Supervisor

Abstract

Biochar provides an effective and inexpensive carbon sequestration technology to combat climate change. It is formed through a process known as pyrolysis; where biomass is thermally decomposed in the absence of oxygen. In this study, a new pyrolysis reactor called the Rotating Heater Pyrolyzer (RHP) was designed and built for biochar production. RHP derived biochar properties were compared to biochars produced with a standard batch pyrolysis reactor (Pyrolytic Shaker Reactor (PSR)) to determine RHP performance. Using several biochar characterization techniques, the soil amendment potential of two solid anaerobic digestate feedstocks were investigated. Woodchip RHP derived biochar processed between 2-3 hrs exhibited similar biochar yield, electrical conductivity, methylene blue adsorption and colour intensity to woodchip PSR biochars produced at 400 °C. Flower waste digestate biochars were found to have properties beneficial for soil amendment, including lower skeletal density, higher electrical conductivity and methylene blue adsorption compared to food waste digestate biochars.

Summary for Lay Audience

Biochar is the solid product of a process known as pyrolysis. During pyrolysis, waste organic material is heated in the absence of oxygen and produces three main products; bio-oil, biochar and permanent gasses. Biochar is the stable solid crystalline form of the carbon that was once present in the original waste material and can take up to centuries to decompose. When incorporated into soils, biochar can effectively create a carbon sink, ultimately delaying greenhouse gas emissions into the atmosphere. In addition to the carbon sequestration abilities of biochar, numerous studies have suggested that biochar can improve soil fertility and agricultural output. Solid anaerobic digestate is one sustainable feedstock that can be used to produce biochar. Anaerobic digestion is the process of producing bio-gas; a renewable source of energy derived from organic waste. It is important to note that biochar properties are highly dependent on pyrolysis parameters and the feedstock used. Therefore, biochar properties must be tailored during production to suit the needs of soil profile it is to be paired with. In this thesis, a new lab scale pyrolysis technology capable of processing relatively large quantities of biomass was designed, built and commissioned. The unit was then used to produce biochar derived from two different solid anaerobic digestate feedstocks, and their soil amendment potential was investigated.

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