BIOFUELS PRODUCTION FROM COTTON GIN WASTE AND RECYCLED PAPER SLUDGE

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0205429
• Project Start Date: Oct 1, 2005
• Project End Date: Sep 30, 2010
• Program Code: [(N/A)]- (N/A)

Recipient Organization
VIRGINIA POLYTECHNIC INSTITUTE
(N/A)
BLACKSBURG,VA 24061

Performing Department
BIOLOGICAL SYSTEMS ENGINEERING

Non Technical Summary
Renewable energy sources can provide the United States with a stable reliable domestic energy supply, contribute very little, if any, net carbon dioxide into the atmosphere, reduce the demand for fossil fuels and hence reduction in NOx, SOx, carbon monoxide, and hydrocarbon emissions into the atmosphere. It can revitalize rural agricultural economies and thus create new jobs. USDA estimated that a 100 million gallon bioethanol plant could create 2,250 local jobs (temporary and/or permanent) in the United States. Cotton gin waste (CGW) is an agro-industrial residue, which could be potentially used for ethanol production. Unlike other lignocellulosic feedstocks, this material is concentrated at the processing sites and therefore harvesting and transportation costs could be considerably less than those for agricultural and forestry residues and dedicated biomass feedstocks. Recycled paper sludge is a short fiber cellulosic feedstock, which could also be potentially used for ethanol production. Similar to the CGW, this material is concentrated at processing sites and therefore transportation cost could be considerably reduced. By combining these feedstocks, ethanol in high yields can be produced for fuel applications and waste disposal problems in these industries can be solved simultaneously. The purpose of this project is to develop an in situ detoxification process for the bioconversion of cotton gin waste and recycled paper sludge mixtures into ethanol in high yields.

Animal Health Component

50%

Research Effort Categories

Basic

50%

Applied

50%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
511	1719	2020	25%
403	1719	2020	25%
511	0660	2020	25%
403	0660	2020	25%

Knowledge Area
511 - New and Improved Non-Food Products and Processes; 403 - Waste Disposal, Recycling, and Reuse;

Subject Of Investigation
0660 - Paper and pulp derived products; 1719 - Cotton, other;

Field Of Science
2020 - Engineering;

Keywords

biomas,

cotton gin waste

ethanol

recycled paper sludge

steam explosion

enzyme hydrolysis

detoxification

fermentation

Goals / Objectives
Our previous studies on cotton gin waste showed that we could produce ethanol at very good yields at one-liter scale level if the pretreated material is properly detoxified. However, the process was not been demonstrated for the cotton gin waste/recycled paper sludge combination. The overall goal of this project is to develop an in situ detoxification process for the bioconversion of cotton gin waste and recycled paper sludge mixtures into ethanol using steam explosion, enzyme hydrolysis, and fermentation technologies. The process has the potential of solving a waste disposal problem while simultaneously generating a new product stream for the cotton and paper and pulp industries. The specific objectives of this project are: 1. Collect and fractionate cotton gin waste from cotton gins in five states to access the impact of harvesting method on the quality of the feedstock. 2. Characterize recycled paper sludge and cotton gin waste from various states to assess impact of ginning on feedstock composition. 3. Investigate the in situ detoxification of cotton gin waste/recycled paper sludge during steam explosion pretreatment. 4. Investigate the bioconversion of steam exploded cotton gin waste/recycled paper sludge mixture to ethanol. 5. Analyze biomass-to-ethanol fermentation residue to assess the nature of the unhydrolyzed residual cellulose. This technology could be applied to other biomass feedstocks and thus eliminate the extra processing step required for the bioconversion of biomass to fuels and chemicals. This will obviously improve the biomass-to-ethanol process economics. The conversion of RPS and CGW to fuel ethanol has other potential advantages. It will solve waste disposal problem in two industries, it will create new jobs in rural America and further it will stimulate both paper recycling and increase processing of cotton. Increased processing of cotton will of course impact USA agriculture, which is one of the goals of the Hatch Program. The processing of cotton gin waste and recycled paper sludge to ethanol will reduce greenhouse gas emission, and replace petroleum products. It cannot be overemphasized that this proposal fits the objectives of this program because it will assist in implementing new ethanol production capacity and it has a potential for near-term applicability and replication in Southern United States.

Project Methods
Objective 1. Collect and fractionate cotton gin waste from cotton gins in five states to access the impact of harvesting method on the quality of the feedstock. a) Collection of cotton gin waste. Cotton gin waste samples will be collected from five cotton gins in Virginia, Mississippi, Texas, Georgia, and North Carolina, and the RPS will be collected from the International Paper recycling facility in Franklin, Virginia. Samples will be collected every year for three years during the project. b) Fractionation of cotton gin waste. About 1 kg dry CGW samples from the five gins will be shipped to the USDA-ARS Cotton Ginning Laboratory, (Stoneville, MS) to be fractionated into clean lint, hulls, sticks/stems, grass, seeds, small leaf, and pin trash. Additionally, some cotton gin waste fractions will be generated from the pilot scale ginning machine for the studies. Objective 2. Characterize recycled paper sludge and cotton gin waste from various states to assess impact of ginning on feedstock composition. The CGW, RPS, and CGW/RPS samples will be analyzed for their summative composition (cellulose, lignin, hemicellulose, ash, and extractives) using ASTM standard methodologies. In addition, the RPS will also be analyzed for elemental composition. Objective 3. In situ detoxification of cotton gin waste/recycled paper sludge during steam explosion pretreatment. a) Steam explosion of cotton gin waste and recycled paper sludge. We will steam explode CGW and RPS mixtures at various CGW to RPS ratios, moisture contents, and severity parameters in the batch steam explosion unit. The CGW and RPS will be steam exploded as received without any milling or presoaking. b) Enzyme hydrolysis of steam exploded material. Steam exploded CGW and RPS will be hydrolyzed independently to determine their hydrolysis rates and their fermentable sugar yields. The hydrolysis will be carried out for 72 h at 50 deg. C using commercial cellulase enzyme preparation such as Spezyme CP. We will investigate various CGW/RPS ratios and the influence of potential heavy metal content of the RPS on the sugar yield. Objective 4. Investigate the bioconversion of steam exploded cotton gin waste/recycled paper sludge mixture to ethanol. a) Fermentation of hydrolysates. We will use both Saccharomyces cerevisiae, and E. coli KO11 for the fermentation. We will investigate the effect of the following parameters on ethanol yield: severity of steam explosion, CGW/RPS ratio, degree of enzyme hydrolysis, composition of CGW, feedstock source, temperature, pH and additives content of RPS. b) Optimization of in situ detoxification process. Factorial designs and response surface methodology will be used to determine the best operating parameters for in situ detoxification and ethanol production. c) Scale-up of process to 1-liter scale. We will scale-up the process from shaker flask level to one-liter scale after the optimization of the process parameters.

Progress 10/01/05 to 09/30/10

Outputs
OUTPUTS: 1. We worked with cotton ginners in southeastern Virginia to collect samples of cotton gin waste for storage studies. Samples of cotton gin waste were stored for several months and the effect of storage stability was evaluated. 2. Cotton gin waste fresh and stored samples were characterized for their ethanol production potential. 3. Cotton gin waste samples were steam exploded to increase surface area and increase accessibility of enzymes to the cellulosic fibers. 4. Recycle paper wastes were collected from pulp mills in Franklin VA and charaterized for their summative composition and their potential for ethanol production. 5. Mixtures of cotton gin waste and recycled paper sludge were steam exploded at various severities to improve on the ethanol production potential from the mixture. 6. Steam exploded cotton gin waste and recycled paper and cotton gin waste were hydrolyzed with enzyme to produce fermentable sugars. 7. The enzyme hydrolyzed residues were fermented with yeast to produce bioethanol. 8. Ethanol products were determined by gas chromatographic analysis. PARTICIPANTS: 1. Jiacheng Shen, graduate student. Obtained PhD from working on this project. 2. Xethanol Inc was one of the sponsors of the program. However, Xethanol is now defunct. TARGET AUDIENCES: 1. Bioethanol production community. 2. Cotton growing community. 3. Cotton ginners community. 4. Rural American communities. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
1. The storage and characterization of the cotton gin waste was critical in estimating the potential amount of bioethanol that could be produced from this raw material. 2. The steam explosion of the cotton gin waste improved the enzyme digestibility of the cotton gin waste. 3. The steam explosion of the combination of recycled paper and cotton gin waste reduced the toxicity of the feedstock and made it more easy to hydrolyze. 5. The steam explosion and enzyme hydrolysis improved on the fermentability of the feedstocks and also increased the ethanol fields. 6. Using the above process steps we were able to demonstrate that cotton gin waste in combination with recycled paper sludge could serve as effective feedstocks for bioethanol production. This approach will simultaneously solve the waste disposal problem while generating ethanol and a new revenue stream for the industry. The project also has the potential to create new jobs in the cotton growing area.

Publications

• Shen, J*., Agblevor, F.A., 2010. Modeling of semi-simultaneous saccharification and fermentation of ethanol production from cellulose, Biomass & Bioenergy, 34:1098-1107.
• Shen, J., Agblevor, F.A. 2010. The operable modeling of simultaneous saccharification and fermentation of ethanol production from cellulose, Applied Biochemistry and Biotechnology: 160:665-681.
• Shen, J*., Agblevor, F.A., 2009, Ethanol production of semi-simultaneous saccharification and fermentation from mixture of cotton gin waste and recycled paper sludge, Bioprocess Biosystems Engineering, DOI 10.1007/s0049.010.0444-4.
• Ibrahim, M., Agblevor, F.A., El-Zawawy W.K. 2010. Isolation and characterization of cellulose and lignin isolated from steam-exploded lignocellulosic biomass. BioResources 5(1): 397-418.
• Agblevor, F.A., Cundiff, J.S., Mingle, C. and Li, W. 2006. Storage and characterization of cotton gin waste for ethanol production. Resource Conservation and Recycling, 46:198-216.

Progress 10/01/08 to 09/30/09

Outputs
OUTPUTS: During the reporting period, we worked on the experimental verification of the previous enzyme hydrolysis models developed for bioethanol production from cotton gin waste and recycled paper sludge. Microcrystalline cellulose hydrolysis and fermentation was investigated. Both the model and experimental data showed that the cell growth was the rate limiting step at the initial fermentation period in the reaction series from cellulose to ethanol. At the later stages of the fermentation, cellulose to cellobiose reaction step controlled the process. The batch model was extended to the continuous and fed-batch operating models. For the continuous simultaneous saccharification and fermentation (SSF) operation, the ethanol productivities increased with increasing dilution rate until a maximum value was attained and then rapidly decreased as the dilution rate approached the washout point. The model predicted a relatively high ethanol yield for the fed-batch operation mode compared to the batch operation mode. PARTICIPANTS: Shen, J. Graduate student. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The results from this work will enable us to design more efficient reactors for the production of bioethanol from cotton gin waste and recycled paper sludge. It will also enable us to accelerate the scale-up of the process development for commercialization. The successful commercialization of this technology will solve a dual problem of providing new product stream to the cotton industry as well as disposing of industrial waste efficiently.

Publications

• Shen, J., Agblevor, F.A. 2009. Operable modeling of simultaneous saccharification and fermentation of ethanol production from cellulose. Applied Biochemistry and Biotechnology. Published on line DOI 10.1007/s12010-009-8650-8.

Progress 10/01/07 to 09/30/08

Outputs
OUTPUTS: During the period we continued work on the modeling and verification of the enzyme hydrolysis and bioethanol production from cotton gin waste (CGW) and recycled paper sludge (RPS). We developed a new halfnated method, Semi-Simultaneous Saccharification and Fermentation (SSSF), for converting steam exploded CGW/RPS mixtures into bioethanol. The results from the modeling and experiments were submitted to Xethanol Inc and also presented at the annual ASABE conference and Spring Annual American Chemical Society meeting . PARTICIPANTS: Jiacheng Shen, Ph.D. graduate student, Virginia Tech. Xethanol Inc. TARGET AUDIENCES: Xethanol Inc and other private bioethanol industries. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Preliminary results and model data showed that the SSSF process produced higher ethanol concentration in the fermentation broth, higher ethanol yield, higher ethanol productivity, than those from simultaneous saccharification and fermentation, and separate hydrolysis and fermentation. These results will have a significant impact on ethanol production from residual biomass and improve on the economics of bioethanol production. Mr Jiacheng Shen a Ph.D. student has completed his Ph.D. dissertaion on the above topic.

Publications

• Shen J, and Agblevor, FA. 2008. Kinetics of enzymatic hydrolysis of steam exploded cotton gin waste. Chemical Engineering Communications, 195:1107-1121 2.Jiacheng Shen and Agblevor, F.A. 2008. Optimization of enzyme loading and hydrolytic time in the hydrolysis of the mixtures of cotton gin waste and recycled paper sludge for the maximum profit rate. Biochemical Engineering Journal. 41:241-250.

Progress 10/01/06 to 09/30/07

Outputs
OUTPUTS: During the period we worked on the modeling of the enzymatic hydrolysis of steam explosion of mixtures of cotton gin waste and recyled paper. The goal was to determine the optimum enzyme loading and its impact on cellulosic ethanol production. Two enzymes samples were compared (Novozymes NS50052 and Spezyme AO3117). These data are very important to the scale-up effort of Xethanol Inc as a step to commercializing the process. The results were submitted to Xethanol Inc, and two manuscripts were submitted for publication and there were two oral presentations at American Society of Agricultural and Biological Engineers meeting and one at the Beltwide Cotton Conference. PARTICIPANTS: FA Agblevor, Associate Professor, Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 Jaicheng Shen, Ph.D. graduate student, Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061. Robin Buller, Vice President, Strategic Development, Xethanol Inc, 1186 Avenue of the Americas, 20th Floor, New York, NY.

Impacts
The results from these studies are going to help Xethanol Inc to scale-up bioethanol production from cotton gin waste. This could have a major impact on the cotton industry because it will simultaneously solve waste disposal problem, add value to the waste, and generate a new revenue stream for the industry.

Publications

• Shen J. and Agblevor, FA. 2007. Kinetics of enzymatic hydrolysis of steam exploded cotton gin waste. Chemical Engineering Communications. (Accepted for publication).
• Agblevor FA, Ibrahim, M, El-Zawawy WK. 2007. Progress on the scale-up of bioconversion of cotton gin waste to ethanol. Presented at the 52nd Annual Beltwide Cotton Conferences, January 9-12, 2007, New Orleans, LA.
• Shen J. and Agblevor, FA. 2007. The hydrolytic kinetics of mixtures of cotton gin waste and recycled paper sludge, and the optimization of enzyme loading and hydrolytic time for a maximum profit rate. Presented at the 2007 Annual International Meeting of ASABE, June 17-20, 2007, Minneapolis, MN.
• Shen J. and Agblevor, FA. 2007. A two-parameter model of hydrolysis of insoluble substrate based on enzyme deactivation and its application in hydrolysis of cotton gin waste. Presented at the 2007 Annual International Meeting of ASABE, June 17-20, 2007, Minneapolis, MN.

Progress 10/01/05 to 09/30/06

Outputs
We have investigated steam explosion pretreatment of mixtures of cotton gin waste and recycled paper sludge for bioethanol production. The cotton gin waste was obtained from Emporia, VA, whereas the recycled paper sludge was obtained from Weyerhaeuser recycling paper mills in Cedar Rapids, IA and Marlboro, SC. We investigated the insitu detoxification of the cotton gin waste samples. In this process, no overliming of the steam exploded material is necessary before hydrolysis and fermentation to ethanol. The mixtures of cotton gin waste to recycled paper sludge in the ratios of 1:1, up to 4:1 were steam exploded at a severity of 3.8. We investigated enzyme hydrolysis of the steam exploded materials using proprietary enzymes from Novozymes Inc, and Genecor Int. Because of the insitu detoxification process, the steam exploded materials were not overlimed before the detoxification. We successfully hydrolyzed 90 percent of reducing usgars in the steam exploded material into monomeric sugars. These results showed a proof of concept that it is not necessary to overlime the samples if the insitu detoxification method is used. The steam explosion process was scale-up to 1000 kg/h and the recycled paper sludge and cotton gin waste were processed on that scale. Our results show that we could scaleup the process successfully.

Impacts
Southside Virginia cotton industry is experiencing waste disposal problems because of potential particulate emissions if the cotton gin waste is combusted. The conversion of the cotton gin waste to bioethanol will simultaneously solve the waste disposal problem and generate new product streams for both industries. Thus, we expect this project to create new jobs in the area when completed. Furthermore, Xethanol Inc, which has acquired rights to the process, plans to build small footprint plants in Southside Virginia and thus provide new jobs in rural Virginia.

Publications

• No publications reported this period