Abstract

There is general agreement in the scientific literature that carbon sequestration is an important tool to mitigate human-induced climate change, but current methods are lacking scalability and economic viability. Though charcoal has been a common fuel for millennia, it has only very recently been purposefully created to sequester carbon. This carbon dense material, called biochar, has been extensively studied as a soil amendment though less studied for industrial applications. Chapter 1 provides an in-depth overview and background discussion of the history and definitions of biochar, distinguishing it from closely related though often misconstrued terms like charcoal, activated carbon, and carbon black. An alternative definition is proposed for each term, acknowledging biochar’s long-held value as a direct soil amendment while framing its future role to help a diverse range of manufacturing industries reduce their environmental impact, mitigate climate change and enhance profitability. Chapter 2 establishes the most extensively used treatment option for high biological oxygen demand (BOD) wastewaters generated by U.S. food manufacturers is publicly owned treatment works (POTW) method. POTW facilities pose a significant obstacle to sustainability efforts since they consume 3-4% of the U.S.’s total electricity production, generating significant greenhouse gas emissions and passing along an “annual wastewater treatment surcharge.” It is of interest therefore to develop a more environmentally friendly and less expensive method for reducing the strength of these effluents at the point of production. Biochar filters derived from renewable and “free” waste material that would otherwise be landfilled is proposed as an option. Little is known about biochar’s potential to treat high BOD organic aqueous food wastes compared to heavy metal ions from traditional manufacturing effluents. This significant research gap was narrowed by gauging the ability of three waste-derived biochars (maple, grapeseed, and soybean curd residue) to lower BOD levels in tofu whey, dairy, and brewery wastewaters compared to activated charcoal using the ASTM D3860-98(2020) aqueous phase adsorption capacity isotherm technique. These effluents were chosen due to their increasing popularity in developing countries, large environmental impact, and the difficulty encountered in physically removing the BOD-causing protein solutes from the surrounding liquid. Results indicate that the biochars can reduce BOD levels below 300 mg L-1 to avoid POTW surcharges, though they require greater volume than commercially available activated carbon. Despite this, widespread adoption of biochar filtration systems by tofu, dairy, and brewery manufacturers appears realistic if: 1) their total annual cost to operate is below the firm’s existing POTW surcharge; 2) low interest financing for the equipment is available; and 3) demand for the nutrient enhanced biochar exists from farmers. Chapter 3 confirms many U.S. food manufacturers’ desire to mitigate their BOD effluents impact due to increased risk of financial surcharges from POTWs, water scarcity issues, and negative societal views of these materials released into public waterways. While acknowledging their efficacy, managers are often reluctant to consider on-site processing without more proof. To overcome this, a lab scale vertically integrated biochar filtration system was empirically tested and large-scaler outcomes extrapolated. In subsequent studies by plant scientists, this high BOD filtered maple biochar was successfully re-utilized as a nutrient-enriched, value-added soil amendment, dramatically improving crop yields. Here fresh weight increased >35% in basil and lettuce above the “no biochar” and “unfiltered biochar” control mixes. This discovery is quite novel since almost all other existing plant/biochar research studies use unmodified (i.e., non-nutrient loaded) biochar and could help food and beverage manufacturers sustainably reduce carbon and water footprints by recycling and monetizing nutrients found in their wastewaters, lowering operating costs. Farmers, in turn, can close regional nutrient cycles by replenishing soil carbons and increase profits by boosting crop yields and reducing the amount of synthetic fertilizer, peat moss, and perlite amendments applied. Carbon black is the main black colorant in many products including commercial printing inks. Obtained from fossil fuels, carbon black imparts high quality black prints, but at a significant global warming cost. Biochar, derived from recycled and renewable resources, has the potential to replace carbon black in many applications. Chapter 4 begins with a discussion of consumers’ desire to switch to a more environmentally sustainable ink but are faced with higher prices, lack of product selection, and print quality concerns. Though much has been written on the progress and sustainability benefits of vegetable (soy) pigment carriers, little has been discussed about the creation of a more sustainable pigment itself. Pre-industrial methods of creating black colorants have largely been forgotten or ignored over the last century due to the ease and low cost of producing carbon black from nonrenewable heavy fuel oils and natural gas. A potential solution was empirically tested evaluating biochar made from used office copy paper, recyclable and unrecyclable cardboard, surplus U.S currency, and eastern white pine to replace carbon black pigments found in flexography, lithography, and inkjet printing inks. Subsequent experiments by other researchers with these biochars showed they can be formulated into a carbon black alternative when properly functionalized for dispersibility and impurities (Goh et al., 2021). A possibility exists therefore for pigment and ink manufacturers to utilize the normally landfilled or burned waste of one process to create an entirely new category of environmentally sustainable and economically viable commercial black inks. In summary, this dissertation focuses on the beneficial environmental, economic, and social implications of converting “free” waste organic materials to biochar to 1) filter food processing wastewater, 2) act as a value-added soil amendment in high value crops, and 3) successfully replace conventional black ink pigments. Chapter 5 synthesizes and concludes the most important sustainability implications and overall findings from each of these investigations to food and ink manufacturers. Closing nutrient cycles by filtering food production effluents at their point of origination with biochar was shown to be a promising alternative to locations where centralized POTW systems are too expensive or non-existent. Though not “perfect,” ink produced by finely ground biochar is a compelling option to that from carbon black in industrial applications when pixilation quality is less of a concern (e.g., printing on boxboard, agricultural painting, etc.). Recommendations and suggestions regarding the future direction of research and policy direction in each sub-field are also provided.

Library of Congress Subject Headings

Biochar--Industrial applications; Carbon sequestration--Technological innovations; Filters and filtration

Publication Date

5-2022

Document Type

Dissertation

Student Type

Graduate

Degree Name

Sustainability (Ph.D.)

Department, Program, or Center

Sustainability (GIS)

Advisor

Guiping Hu

Advisor/Committee Member

Nabil Z. Nasr

Campus

RIT – Main Campus

Plan Codes

SUST-PHD

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