Non Technical Summary
The goal of this project is to scale up a patent-pending composting technology that will promote the US bioeconomy by increasing the use of 100% cotton textiles while also increasing the circularity and overall sustainability of the US Cotton Industry.This proposal directly addresses Topic 7G, Subtopic 19 which requests submissions on "cotton composting". Specifically, post-consumer, 100% cotton textile materials will undergo composting with gaseous CO2 capture to generate a compost product for soil regeneration and a relatively high purity CO2 gaseous product for utilization. The technology has been developed and optimized in the lab of PD Sagues at 0.5L and 25L scales using a mixture of textile waste and food waste. In the proposed project, we will take advantage of NC State University's permitted compost facility by constructing a new demo-scale 25,000L (3m x 3m x 3m) compost bioreactor to demonstrate the technology at larger scale. CO2 captured during the project will be utilized by our industrial partner Sunrock by treating alkaline wastewater from their Butner quarry north of Durham NC. Cotton Incorporated provided the initial seed funding to prove this composting technology at the lab and pilot scales and is committed to providing support during scale-up in the form of textile waste supply and general consulting. The primary composting variables that will be assessed include dye type, textile mass loading, and particle size.

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
402	1719	2020	100%

Knowledge Area
402 - Engineering Systems and Equipment;

Subject Of Investigation
1719 - Cotton, other;

Field Of Science
2020 - Engineering;

Goals / Objectives
The goal of this project is to scale up a patent-pending composting technology that will promote the US bioeconomy by increasing the use of 100% cotton textiles while also increasing the circularity and overall sustainability of the US Cotton Industry. This proposal directly addresses Topic 7G, Subtopic 19 which requests submissions on "cotton composting". Specifically, post-consumer, 100% cotton textile materials will undergo composting with gaseous CO2capture to generate a compost product for soil regeneration and a relatively high purity CO2gaseous product for utilization. The technology has been developed and optimized in the lab of PD Sagues at 0.5L and 25L scales using a mixture of textile waste and food waste. In the proposed project, we will take advantage of NC State's existing compost facility by constructing a new demo-scale 25,000L (3m x 3m x 3m) compost bioreactor to demonstrate the technology at larger scale. A successful demonstration at such a scale will dramatically increase the odds of commercialization. Although commercialization is not within scope of this project,Sunrock Carolina issupportive and will be ready to commercialize should the project be a success (see Letters of Support).Sunrock Carolina is a mining company headquartered in Raleigh, NC with operations across the US and Canada. Sunrock purchases compost and CO2for their operations, making this technology particularly attractive as they verticalize their operations. CO2captured during the project will be utilized and removed by Sunrock by treating alkaline wastewater from their Butner quarry north of Durham NC; the CO2will be removed, or sequestered, via a mineralization reaction with alkaline silicates to form stable calcium and magnesium bicarbonate salts.Cotton Incorporated provided the initial seed funding to prove this composting technology at the lab and pilot scales and is committed to providing support during scale-up in the form of textile waste supply and general consulting. Approximately 12 million tonnes of textile waste are landfilled each year in the US, representing 8% of total waste landfilled.The patent-pending composting technology uses an innovative reactor, gas control system, and robust wildtype microbes to generate CO2gas to be extracted, utilized, and removed.To the best of our knowledge, PD Sagues is the first in the world to develop and demonstrate a composting process with CO2capture; the technology was initially showcased and filed for patentin 2022 using food waste as the primary waste feedstock. To make progress towards realizing the full potential of the proposed technology the following six objectives will be achieved in this project:Objective 1: Construction and commission of new demo-scale compost bioreactor: A new 25,000L (3m x 3m x 3m) compost bioreactor will need to be constructed at NC State's permitted compost facility to allow for scale up experiments.Objective 2: Assess impact of dyes in demo-scale compost bioreactor: Understand impact, if any, of dyes on textile waste composting by testing 5 different dye conditions.Objective 3: Maximize cotton textile loading rate: Identify the maximum textile waste loading rate by testing 4 different loading conditions.Objective 4: Assess impact of whole textile clothing items: Understand the degradability of whole textile clothing items as compared to shredded textiles.Objective 5: CO2 utilization trial runs: Captured CO2 will be utilized to treat alkaline wastewater from industrial partner Sunrock.Objective 6: Techno-economic & life cycle assessment: Data collected from Objectives 1 - 5 will be used to under the economic feasibility of capturing, utilizing, and removing CO2 at scale.

Project Methods
This project will involve relatively large scale experimentation using a demo-scale (25,000L or 3m x 3m x 3m) compost bioreactor. The nature of the research will require short periods of high intensity work, which will be co-led by PD Sagues and a graduate student and assisted by undergraduate students and full-time staff at NC State's commercial compost facility. PD Sagues will leverage his extensive experience scaling up bioprocessing technologies to ensure objectives are met in a timely manner. The variables to test in the demo-scale bioreactor have been carefully selected to maximize impact while maintaining practicality. A conservative estimate of 18 months will be necessary to complete all experimentation. Should there be delays, there will be sufficient time over the 24 month grant period to complete all composting experiments. The large scale of experimentation using the demo-scale reactor makes the use of replicates during experimentation impossible. Each experiment will involve one set of conditions being carried out in one demo-scale bioreactor. Statistical methods will still be applied across experiments to identify significant differences, with the assumption that non-target parameters remain relatively constant across experiments. Non-target, constant parameters include C:N ratio, moisture content, total mass, retention time, and oxygen gradient in the pile. Target, variable parameters include textile dye, textile loading, and textile particle size. The assumption that non-target parameters remain constant across experiments is bolstered at large scales of operation. Demo-scale experimentation is traditionally carried out in this manner due to budgetary and time constraints.Each compost experiment will involve the following non-target, constant parameter values: C:N ratio of 30:1 using consistent mix of food waste, landscaping waste, animal bedding, and cotton textile, initial moisture content of 65%, total mass of 12.5 tonne (wet weight), and retention time of 21 days. The patent-pending gas control system will generate an oxygen gradient in the compost pile, with the top of the pile having a higher oxygen concentration than the bottom, as shown in Figure 3A. Data generated at the pilot scale (25L) have shown that the oxygen gradient does not negatively impact the composting process since the microbes are never oxygen deprived, and we expect the same observation at large scale. It is assumed that the oxygen gradient will be approximately the same for each experiment. The target parameters that will vary include the textile dye, textile loading, and textile particle size, as explained in the subsequent sections.