Doreen Ntiamoah-Asare
University of Texas at Arlington, PhD Civil Engineering
EREF Scholar 2023
According to EPA Toxics Release Inventory Analysis in 2017, pulp and paper mills released about 79,000 tons (5%) of all industrial pollutant releases in 2015. 66% into the air, 10% into water, 24% onto land. These waste effluents can pollute the air, cause severe harm to aquatic life, disturb food chains, and cause various health implications. Also, globally, yearly sugarcane production is around 1.6 billion tons, which produces approximately 279 million metric tons of bagasse (Ajala et al 2021; Chandel et al. 2012); and according to Costa et al. (2014), bagasse is usually burned in boilers, which emits a variety of air pollutants e.g. PM, CO, SO2, NOx, TOCs, VOCs etc. (EPA AP-42, 1993). Pulp and paper wastes as well as bagasse can end up in landfills, with its resulting environmental challenges. Pulp and paper waste and bagasse contain high levels of lignin, which is recalcitrant to biodegradation due to its structure. Hard woods have lignin content of 28–30%, soft woods contain 32–42%, and bagasse contains 17 – 23%. Not only is lignin recalcitrant to biodegradation itself, but it also often shields cellulose and hemicellulose, making them inaccessible to microbial degradation. To be able to convert pulp and paper and bagasse wastes to renewable energy in the form of biogas, there is a critical need to break down the lignin. However, most physical/chemical methods of degrading lignin are costly and often produce toxic intermediates. Most biological pathways of degrading lignin are aerobic, and do not work in the anaerobic conditions associated with digesters; they would thus require an additional pre-treatment reactor, which increases costs. To achieve anaerobic degradation of lignin, this research uses a novel approach: seeding with termite-gut microorganisms (TAV5). TAV5 is a bacterium strain of the family Opitutaceae from Termite-Associated Verrucomicrobium, isolated from the hindgut of Reticulitermes flavipes, the most common subterranean termite in North America. The genome of TAV5 contains genes coding for enzymes that could structurally modify lignin (Kotak et al., 2015; Rahimi 2020). The overall goal of this research is to investigate the use of TAV5 to biodegrade lignin and boost methane production from two waste streams: pulp and paper waste and bagasse. If these waste streams can be diverted to anaerobic digestion using TAV5 to biodegrade into biogas, not only will it produce renewable energy which is sustainable. It could also reduce the use of non-renewable energy sources such as fossil fuels, which eventually could also reduce carbon footprint and emissions of other air pollutants. Also, wastes entering landfills will be reduced, save landfill space, and extend its life.
Biography
Doreen is a Ph.D. student in Civil Engineering at the University of Texas at Arlington, majoring in Sustainable Solid Waste Engineering and Management. She joined UTA in Fall 2020 and her research focuses on investigating Termite gut microbes (TAV5) application to sugarcane bagasse and pulp and paper waste to enhance lignin degradation to boost methane production in anaerobic digestion. She hopes to complete in Fall 2024. Doreen has worked on various research projects at UTA, including “Prioritizing Organic Waste to Energy – Renewable: Development and Application of the POWER Framework,” sponsored by Center for Transportation, Equity, Decisions and Dollars, a U.S. Department of Transportation Center. She worked on estimating energy production, emissions, and costs for co-digestion of food waste in selected counties in the Dallas Fort Worth Metroplex, Vermont state, and City of Las Vegas. She was also involved in a project that collected fuel efficiency and emissions data from vehicles with and without a fuel additive. She has also contributed to a project aiming to boost production of methane for renewable energy from agricultural wastes, sponsored by the U.S. Department of Agriculture. Prior to joining UTA, she worked with Zoomlion Ghana Limited, Ghana, on several international projects related to solid waste management, such as construction of a sanitary landfill in Fiamah, Monrovia Liberia (World Bank Project), and solid waste management projects in Equatorial Guinea, Zambia, and Angola. She has also worked with Bay Associates Environmental Inc., a hazardous waste management company in Catonsville, Maryland. She earned her B.S. in Water and Sanitation from the University of Cape Coast in Ghana, West Africa in 2008, and her Master of Engineering in Environmental, Health and Safety from the University of Malaya, Kuala Lumpur in Malaysia in 2017.
